{"version":1,"scope":"full","truncated":false,"id":"editorial-bazi-solar-term-boundary","url":"https://wenbu.app/en/learn/bazi-solar-term-boundary/","locale":"en","revision":"f596d7521bdb17cce1c5a0c0e1dd1cb22ea3dbdbba661620da8d9d153d617328","updated":"2026-11-14T07:17:00.082Z","content":"# Born on a solar-term day: which instant decides the year and month pillars\n\nA boundary-day worksheet for births on a solar-term transition: record the date, local clock time, IANA zone and solar-term instant, then mark the year and month pillars settled or open. No pillar is picked from the date alone.\n\nUpdated: 2026-11-01 · Wenbu AI-assisted editorial\n\nStart with the conclusion: “born on the day of Li Chun” or “born on a month’s solar-term day” does not by itself decide the year or month pillar. Under Wenbu’s published conventions, the year and month pillars are produced by comparing the birth’s absolute instant with the solar-term instant, using a fixed UTC+08:00 standard time without adding historical daylight saving; the day and hour pillars default to the selected local clock. What matters is therefore which instant comes first — the birth or the solar term — not the date on the calendar. Write four items on one line: the Gregorian birth date, the local clock time to the minute, the birthplace IANA zone such as Asia/Shanghai, and the relevant solar-term instant. If the record cannot establish the order, mark the affected pillar “open” and keep both results rather than choosing one.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- On a transition day, the year and month pillars depend on whether the birth instant or the solar-term instant comes first; the date alone cannot decide.\n\n- The worksheet needs four inputs: Gregorian date, local clock time, IANA zone and the relevant solar-term instant.\n\n- When the record is too imprecise, mark the pillar open and keep both results instead of forcing a choice.\n\n- Apparent-solar-time correction affects the day and hour pillars; the year and month pillars still use the original absolute instant.\n\n## Flow for judging a solar-term boundary\n\n1. **Restore the absolute instant** — Use the birth date, local clock time and birthplace IANA zone to fix the absolute instant of birth; do not substitute the current residence zone for the birthplace zone.\n\n2. **Obtain the solar-term instant** — Look up the relevant term’s transition instant — Li Chun for the year pillar, the relevant jie for the month pillar — as the dividing point.\n\n3. **Compare the order** — Compare the birth instant with the transition instant. The year and month pillars use this comparison on fixed UTC+08:00 without historical daylight saving.\n\n4. **Mark each pillar** — If the order is clear, mark “settled”; if the record’s precision spans the dividing point, mark “open” and keep both results.\n\n5. **Save the record** — Save the date, clock time, zone, solar-term instant and marks together, noting the conventions used, so another chart can be compared item by item.\n\nStarting from the birth record, decide whether the year and month pillars are genuinely uncertain. Each step keeps the original inputs so another person can check them; the flow covers only the solar-term boundary for the year and month pillars, not the day-boundary rule or offset conversion details.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md)\n\n## Why “that day” cannot settle a pillar\n\nA solar term is not a whole day; it is an astronomical instant. The 24 solar terms divide the sun’s position along the ecliptic, and each term begins at a specific moment. The year pillar changes at the Li Chun transition, and the month pillar changes at the relevant jie term. Two births on the same date can therefore land on different year or month pillars depending on which side of the transition they fall. Treating “the day of Li Chun” as one block merges two different instants.\n\nThis is also why a pillar cannot be inferred from the date. A date gives an interval; the transition instant gives the dividing line. Wenbu’s published notes state that the year and month pillars compare the birth’s absolute instant with the solar-term instant, using fixed UTC+08:00 without adding historical daylight saving. In other words, first restore the birth record to an absolute instant, then compare it with the solar-term instant — do not read the pillar off the calendar day.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## The boundary worksheet: four inputs, one mark per pillar\n\nWrite the Gregorian birth date on the first line, the local clock time with its precision on the second (for example “about mid-morning” or “08:37 recorded”), the birthplace IANA zone name on the third, and the relevant solar-term instant on the fourth. If any of the four is missing, the judgment stops at “open.” If the original record has only a date and no time, the year and month pillars near a transition cannot be settled; in that case Wenbu provisionally uses local noon for the year and month pillars and flags uncertainty on solar-term days, and that provisional value should not be treated as confirmed.\n\nThen mark each pillar. The year pillar is “settled” only when the order of the birth instant and the Li Chun transition is clear. The month pillar is “settled” only when the order of the birth instant and that month’s jie transition is clear. The day and hour pillars are a separate layer: they default to the selected local clock and are affected by the day-boundary rule and the apparent-solar-time setting. This worksheet does not handle the 23:00 Zi day boundary, and it does not handle offset or daylight-saving conversion details; those belong to the other two guides.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Record precision sets the strength of the conclusion\n\n“08:37” and “a bit after eight” are not the same kind of evidence. If the solar-term instant falls outside the interval covered by the record’s precision, the conclusion is stable; if it falls inside, the honest answer is “open.” Suppose the record says “about mid-morning” and the transition is at 10:42: an earlier and a later birth in that morning would give different results, so no single pillar should be chosen. Keeping both possibilities and noting “birth record too imprecise” is more useful than a pillar that looks certain.\n\nSeparate calculation uncertainty from interpretive uncertainty. Even when a pillar is settled, whether a traditional interpretation holds is a different question; a calculation can be reproduced by convention without the interpretation being scientifically validated. The worksheet addresses only the first: it lays out the inputs, the instants and the dividing line so another person can check them. It does not judge which interpretation is better, and it does not choose a school for the reader.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md)\n\n## Common mistakes and the limits of this page\n\nThe first mistake is treating Lunar New Year as the year-pillar boundary. The year pillar changes at the Li Chun transition, not at the first day of the first lunar month, so births around Spring Festival are especially easy to misjudge. The second is applying apparent-solar-time correction to the year and month pillars. Wenbu’s notes say that with the correction enabled, the day and hour pillars use an approximate longitude and equation-of-time adjustment, while the year and month pillars still use the original absolute instant; applying the correction again to the transition comparison introduces a new error.\n\nThe third mistake is guessing a time zone from historical jurisdiction. This page does not supply, and will not invent, historical administrative rules; what is needed is the birthplace’s IANA zone name and the offset actually in effect on that date. If a local clock time was skipped or repeated during a daylight-saving change, Wenbu’s chart rejects such ambiguous or nonexistent input, so supply an explicit UTC offset instead of picking one arbitrarily. The solar-term instant itself is an astronomical calculation, separate from local clock adjustments.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Solar-term boundary worksheet: what to record and how to judge\n\n| Item | What to record | Decision rule |\n| --- | --- | --- |\n| Birth date | Gregorian date, noting whether it is the original record | The date alone does not decide a pillar; it locates the relevant term |\n| Local clock time | Birthplace clock time and precision (to the minute, or “about mid-morning”) | If precision spans the transition, mark the affected pillar open |\n| IANA zone | Birthplace zone name, e.g. Asia/Shanghai | Used to restore the absolute instant; do not substitute the current residence zone |\n| Solar-term instant | Li Chun for the year pillar; the relevant jie for the month pillar | Birth before the transition uses the earlier pillar; after it uses the later one |\n| Year pillar status | Settled / open | Settled only when the order against the Li Chun transition is clear |\n| Month pillar status | Settled / open | Settled only when the order against that month’s jie transition is clear |\n| Day and hour pillars | Attach the day-boundary rule and solar-time setting separately | Not judged here; they default to the local clock |\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Hypothetical case: a boundary worksheet for a Li Chun transition day\n\nThe following is a teaching scenario, not a real person’s data, and it makes no claim about anyone’s fate. Suppose a birth record says “the morning of February 4,” with Shanghai as the birthplace and Asia/Shanghai as the zone; suppose that year’s Li Chun transition was at 10:42 on February 4 (an illustrative value used only to demonstrate the process — the actual instant should be looked up).\n\n1. Step one, write the inputs: Gregorian February 4; clock time “morning,” precision insufficient; IANA zone Asia/Shanghai; Li Chun transition 10:42. List all four before guessing any pillar.\n\n2. Step two, restore the absolute instant: Shanghai used UTC+08:00 on that date, so “morning” corresponds to an interval, not a single instant. The year and month comparison uses fixed UTC+08:00 without historical daylight saving.\n\n3. Step three, compare the order: a birth before 10:42 and a birth after it fall on opposite sides of Li Chun, so because the record says only “morning,” the interval crosses the dividing point and the year pillar cannot be uniquely determined.\n\n4. Step four, mark each pillar: mark the year pillar “open” and keep both the pre-Li Chun and post-Li Chun results; the month pillar likewise depends on that month’s jie transition, and if that also falls inside the interval, mark it open too.\n\n5. Step five, save the record: write the date, “morning,” Asia/Shanghai, 10:42 and “year pillar open” together, noting that this is an open conclusion caused by insufficient precision, not a calculation error.\n\nThe specific lesson is that on a transition day the question is not “which day” but “does the birth-time interval cross the dividing point.” When it does, the correct output is “open plus both results,” not a pillar picked from the date. Only when the record is refined to the minute and confirmed to fall before or after 10:42 does the year pillar move from open to settled.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## FAQ\n\n### If I was born on the day of Li Chun, is the year pillar always the new year’s?\n\nNot necessarily. The year pillar changes at the Li Chun transition instant, not at midnight of that date. A birth before the transition still belongs to the previous year pillar; only a birth after it enters the new one. Comparing the birth’s absolute instant with the Li Chun instant is what settles it.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md)\n\n### Does the month pillar change with the lunar month?\n\nNo. Under Wenbu’s published conventions, the month pillar changes at the relevant jie transition, comparing the birth’s absolute instant with the solar-term instant. The lunar month is a different calendar label and cannot serve directly as the month-pillar boundary.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n### Does enabling apparent solar time change the year and month pillars too?\n\nNot in the same way. The apparent-solar-time correction applies to the day and hour pillars through an approximate longitude and equation-of-time adjustment; the year and month pillars still compare the original absolute instant with the solar-term instant. Applying the correction again to the transition comparison introduces error.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md)\n\n### What if I only remember the date, not the time?\n\nMark the year and month pillars open; do not infer them from the date. When the birth time is unknown, Wenbu omits the hour pillar, provisionally uses local noon for the year and month pillars, and flags uncertainty on solar-term days; treat that provisional value as a placeholder to be checked, not a conclusion.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n### Two charts disagree on the year pillar — what should I check first?\n\nCheck the birth date, local clock time and birthplace IANA zone first, then compare the solar-term instant and comparison convention each chart uses. Compare item by item and change one setting at a time to see which layer causes the difference, rather than arguing about interpretation first.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Glossary\n\n- **Solar-term transition instant**: The specific astronomical moment at which a solar term begins; it is the boundary for changing the year and month pillars, not a whole day. [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md)\n\n- **Absolute instant**: The point in time fixed by the birth date, local clock time and birthplace zone, used for comparison with the solar-term instant. [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- **Open**: A mark for a pillar when the birth record’s precision cannot establish whether the birth came before or after the solar-term boundary; both results must be kept. [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- **Fixed UTC+08:00 standard time**: The UTC+08:00 standard used by Wenbu when comparing the year and month pillars with solar-term instants, without adding historical daylight saving. [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Evidence notes\n\n- Wenbu compares the year and month pillars using the birth's absolute instant against the solar-term instant, on fixed UTC+08:00 without historical daylight saving. — “年、月柱按出生绝对时刻与节气时刻比较，使用固定东八区标准时” (fact); [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- When the birth time is unknown, Wenbu omits the hour pillar, provisionally uses local noon for the year and month pillars, and flags uncertainty on solar-term days. — “出生时间未知时不生成时柱，年、月柱以当地中午暂定，交节日会提示不确定性。” (fact); [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- Editorial principle: the date, time zone and boundary settings must be saved with the result, because eight characters alone are not reproducible. — “Save the date, time zone and boundary settings with the result.” (editorial); [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Sources\n\n- [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) — Existing editorial and reproducible chart conventions; fetched 2026-11-01T13:00:34.984Z; complete response\n\n- [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) — Existing editorial and boundary examples; fetched 2026-11-01T13:00:34.988Z; complete response\n\n- [Wenbu · calculation conventions](https://wenbu.app/methodology/) — First-party implementation; not evidence of predictive accuracy; fetched 2026-11-01T13:00:34.984Z; complete response\n\n- [lunar-typescript · official source](https://raw.githubusercontent.com/6tail/lunar-typescript/master/README.md) — Calculation implementation and conventions; fetched 2026-11-01T13:00:34.984Z; complete response\n\n[Check one solar-term boundary in Wenbu’s BaZi chart](https://wenbu.app/en/bazi/)\n\n# What changes when you round a BaZi time-zone offset?\n\nEnter one Kathmandu clock time with three time-zone settings and check how rounding 15 minutes changes the year and month pillars at Li Chun.\n\nUpdated: 2026-11-14 · Wenbu AI-assisted editorial\n\nFor February 3, 2025 at 20:00 in Kathmandu, Wenbu resolves Asia/Kathmandu and +05:45 to 14:15 UTC. After Li Chun, the year and month pillars are Yi Si and Wu Yin. With +06:00 and the same clock time the instant moves earlier, to 14:00 UTC. Before Li Chun, the pillars are Jia Chen and Ding Chou. Keep the minutes in the recorded offset when comparing the charts.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json) · [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm)\n\n- Copy the hours and minutes of the offset. Subtracting 5 hours and 45 minutes from 20:00 gives 14:15 UTC.\n\n- Compare the two UTC instants before you inspect the pillars. Both input forms still show the same date and clock time.\n\n- If the original record is ambiguous, keep each supported offset on its own line until you can check its source.\n\n## One local clock time and two sides of Li Chun\n\n1. **Locate Li Chun** — Hong Kong time 22:10 is about 14:10 UTC.\n\n2. **Keep the offset minutes** — Subtract 05:45 from 20:00 to get 14:15 UTC.\n\n3. **Keep an explicit comparison** — Subtract 06:00 instead to get 14:00 UTC.\n\nPlace the two chart instants and the time of Li Chun on one UTC timeline.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## Put the chart inputs and the solar term on the same clock\n\nIn the February page of the Hong Kong Observatory Almanac 2025, find Spring Commences in the Solar Terms column. It gives February 3 at 22:10 in Hong Kong, which is UTC+08:00. That is 14:10 UTC to the stated minute. The two test instants fall on either side.\n\nRounding the offset up moves the computed UTC time earlier. Start from the same 20:00 each time. Subtract 5 hours and 45 minutes to get 14:15, or subtract 6 hours to get 14:00. The local date stays February 3 in both input records.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## Check the two fields that changed\n\nIn the birth time-zone field, choose Other region / custom timezone. Try Asia/Kathmandu, +05:45 and +06:00 in turn. Keep February 3 and 20:00 fixed, use the midnight day boundary, and leave apparent solar time off. In the result, copy Timezone / offset and the two characters shown for each of the year and month pillars.\n\nAll three runs keep Gui Mao 癸卯 for the day and Ren Xu 壬戌 for the hour. Under these settings both pillars use the same local clock. Keep the entered zone, the resolved offset and the UTC instant with the four pillars so you can trace the cause of the difference.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## Three runs with the same 2025-02-03 20:00 local input\n\n| Time zone entered | UTC | Relative to Li Chun | Year / month |\n| --- | --- | --- | --- |\n| Asia/Kathmandu | 14:15 | After | Yi Si 乙巳 / Wu Yin 戊寅 |\n| +05:45 | 14:15 | After | Yi Si 乙巳 / Wu Yin 戊寅 |\n| +06:00 (rounded comparison) | 14:00 | Before | Jia Chen 甲辰 / Ding Chou 丁丑 |\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## Make a record someone else can reproduce\n\nImagine a fictional record that reads “2025-02-03 20:00, Kathmandu”. A spreadsheet later lists the zone as UTC+6.\n\n1. Start with Asia/Kathmandu and record the reported offset. In a structured calculation result, calendar.instant shows 14:15Z.\n\n2. Run the same date and time with +05:45 and compare the two year and month pillars.\n\n3. Enter +06:00 as a separate comparison. Record 14:00Z, Jia Chen and Ding Chou on that line and mark the offset as rounded.\n\n4. Keep the almanac page and its time beside the comparison. To share a reproducible example, include the date, time, zone and whether apparent solar time was enabled.\n\nThe worksheet explains the mismatch and gives the next reader enough to rerun it.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## FAQ\n\n### Is “Kathmandu, 20:00” enough in a chart record?\n\nAdd the Gregorian date so the offset can be resolved for that day. Keep the location-based zone and the resolved offset together when you have both.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n### What if the recorded birth is also at 14:10 UTC?\n\nThe two inputs in this example are 14:00 and 14:15. If your record is in the same displayed minute as a solar term, check a more precise source, the precision of the birth record and the calculator’s convention before fixing the result.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## Glossary\n\n- **Fixed UTC offset**: A specified difference from UTC. Here +05:45 places the local clock five hours and forty-five minutes ahead of UTC. [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n- **Solar-term instant**: The time of Li Chun used in this comparison. Put it on the same clock as the test times to compare their order. [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm) · [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n## Evidence notes\n\n- Wenbu takes a location-based IANA time zone or a fixed UTC offset as input. — “IANA 时区名称或明确的 UTC 偏移” (fact); [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- The year and month pillars depend on how the birth instant falls relative to the solar terms. — “Absolute solar-term boundaries in fixed UTC+08:00” (fact); [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json)\n\n- An offset for an older date may differ from a region’s current offset. — “Today’s UTC offset may differ from the historical offset at birth” (fact); [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md)\n\n- The Hong Kong Observatory publishes year-by-year Gregorian and lunar calendar tables. — “Gregorian-Lunar Calendar Conversion Table” (fact); [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm)\n\n## Sources\n\n- [Current complete zh canonical article](https://wenbu.app/knowledge/zh/bazi-solar-term-boundary.md) — Current public original and earlier additions; add substantial coverage without repeating or replacing them.; fetched 2026-11-14T07:03:17.804Z; complete response\n\n- [Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-solar-term-boundary.md) — Current public original and earlier additions; add substantial coverage without repeating or replacing them.; fetched 2026-11-14T07:03:17.815Z; complete response\n\n- [Wenbu · calculation conventions](https://wenbu.app/methodology/) — First-party implementation; not evidence of predictive accuracy; fetched 2026-11-14T07:03:17.842Z; complete response\n\n- [Wenbu · birth time and time zones](https://wenbu.app/knowledge/en/birth-time-timezone.md) — Existing editorial and boundary examples; fetched 2026-11-14T07:03:17.846Z; complete response\n\n- [Hong Kong Observatory · calendar conversion](https://www.hko.gov.hk/en/gts/time/conversion.htm) — Official calendar reference; not evidence of fortune-telling; fetched 2026-11-14T07:03:18.700Z; complete response\n\n- [lunar-typescript · official source](https://raw.githubusercontent.com/6tail/lunar-typescript/master/README.md) — Calculation implementation and conventions; fetched 2026-11-14T07:03:17.993Z; complete response\n\n- [Wenbu · versioned public capabilities](https://wenbu.app/capabilities.json) — First-party current tool, convention and privacy contract; not external endorsement or predictive validation; fetched 2026-11-14T07:03:17.844Z; complete response\n\n[Compare the three entries in the BaZi tool](https://wenbu.app/en/bazi/)","edition":{"title":"What changes when you round a BaZi time-zone offset?","description":"Enter one Kathmandu clock time with three time-zone settings and check how rounding 15 minutes changes the year and month pillars at Li Chun.","answer":"For February 3, 2025 at 20:00 in Kathmandu, Wenbu resolves Asia/Kathmandu and +05:45 to 14:15 UTC. After Li Chun, the year and month pillars are Yi Si and Wu Yin. With +06:00 and the same clock time the instant moves earlier, to 14:00 UTC. Before Li Chun, the pillars are Jia Chen and Ding Chou. Keep the minutes in the recorded offset when comparing the charts.","answerSourceIds":["methods","birth","capabilities","hko"],"evidence":[{"claim":"Wenbu takes a location-based IANA time zone or a fixed UTC offset as input.","sourceId":"methods","quote":"IANA 时区名称或明确的 UTC 偏移","kind":"fact"},{"claim":"The year and month pillars depend on how the birth instant falls relative to the solar terms.","sourceId":"capabilities","quote":"Absolute solar-term boundaries in fixed UTC+08:00","kind":"fact"},{"claim":"An offset for an older date may differ from a region’s current offset.","sourceId":"birth","quote":"Today’s UTC offset may differ from the historical offset at birth","kind":"fact"},{"claim":"The Hong Kong Observatory publishes year-by-year Gregorian and lunar calendar tables.","sourceId":"hko","quote":"Gregorian-Lunar Calendar Conversion Table","kind":"fact"}],"takeaways":["Copy the hours and minutes of the offset. Subtracting 5 hours and 45 minutes from 20:00 gives 14:15 UTC.","Compare the two UTC instants before you inspect the pillars. Both input forms still show the same date and clock time.","If the original record is ambiguous, keep each supported offset on its own line until you can check its source."],"sections":[{"heading":"Put the chart inputs and the solar term on the same clock","paragraphs":["In the February page of the Hong Kong Observatory Almanac 2025, find Spring Commences in the Solar Terms column. It gives February 3 at 22:10 in Hong Kong, which is UTC+08:00. That is 14:10 UTC to the stated minute. The two test instants fall on either side.","Rounding the offset up moves the computed UTC time earlier. Start from the same 20:00 each time. Subtract 5 hours and 45 minutes to get 14:15, or subtract 6 hours to get 14:00. The local date stays February 3 in both input records."],"sourceIds":["methods","hko","capabilities"]},{"heading":"Check the two fields that changed","paragraphs":["In the birth time-zone field, choose Other region / custom timezone. Try Asia/Kathmandu, +05:45 and +06:00 in turn. Keep February 3 and 20:00 fixed, use the midnight day boundary, and leave apparent solar time off. In the result, copy Timezone / offset and the two characters shown for each of the year and month pillars.","All three runs keep Gui Mao 癸卯 for the day and Ren Xu 壬戌 for the hour. Under these settings both pillars use the same local clock. Keep the entered zone, the resolved offset and the UTC instant with the four pillars so you can trace the cause of the difference."],"sourceIds":["methods","birth","capabilities"]}],"figure":{"title":"One local clock time and two sides of Li Chun","caption":"Place the two chart instants and the time of Li Chun on one UTC timeline.","sourceIds":["methods","hko","capabilities"],"steps":[{"label":"Locate Li Chun","detail":"Hong Kong time 22:10 is about 14:10 UTC."},{"label":"Keep the offset minutes","detail":"Subtract 05:45 from 20:00 to get 14:15 UTC."},{"label":"Keep an explicit comparison","detail":"Subtract 06:00 instead to get 14:00 UTC."}]},"table":{"title":"Three runs with the same 2025-02-03 20:00 local input","columns":["Time zone entered","UTC","Relative to Li Chun","Year / month"],"rows":[["Asia/Kathmandu","14:15","After","Yi Si 乙巳 / Wu Yin 戊寅"],["+05:45","14:15","After","Yi Si 乙巳 / Wu Yin 戊寅"],["+06:00 (rounded comparison)","14:00","Before","Jia Chen 甲辰 / Ding Chou 丁丑"]],"sourceIds":["methods","birth","capabilities"]},"example":{"title":"Make a record someone else can reproduce","intro":"Imagine a fictional record that reads “2025-02-03 20:00, Kathmandu”. A spreadsheet later lists the zone as UTC+6.","steps":["Start with Asia/Kathmandu and record the reported offset. In a structured calculation result, calendar.instant shows 14:15Z.","Run the same date and time with +05:45 and compare the two year and month pillars.","Enter +06:00 as a separate comparison. Record 14:00Z, Jia Chen and Ding Chou on that line and mark the offset as rounded.","Keep the almanac page and its time beside the comparison. To share a reproducible example, include the date, time, zone and whether apparent solar time was enabled."],"conclusion":"The worksheet explains the mismatch and gives the next reader enough to rerun it.","sourceIds":["methods","birth","capabilities"]},"faq":[{"question":"Is “Kathmandu, 20:00” enough in a chart record?","answer":"Add the Gregorian date so the offset can be resolved for that day. Keep the location-based zone and the resolved offset together when you have both.","sourceIds":["methods","birth","capabilities"]},{"question":"What if the recorded birth is also at 14:10 UTC?","answer":"The two inputs in this example are 14:00 and 14:15. If your record is in the same displayed minute as a solar term, check a more precise source, the precision of the birth record and the calculator’s convention before fixing the result.","sourceIds":["methods","hko","capabilities"]}],"glossary":[{"term":"Fixed UTC offset","definition":"A specified difference from UTC. Here +05:45 places the local clock five hours and forty-five minutes ahead of UTC.","sourceIds":["methods","birth","capabilities"]},{"term":"Solar-term instant","definition":"The time of Li Chun used in this comparison. Put it on the same clock as the test times to compare their order.","sourceIds":["methods","hko","capabilities"]}],"cta":{"label":"Compare the three entries in the BaZi tool","reason":"Change just the time-zone field, then compare the reported offset with the year and month pillars."}},"editionScope":"addition","sources":[{"id":"current-zh","title":"Current complete zh canonical article","url":"https://wenbu.app/knowledge/zh/bazi-solar-term-boundary.md","role":"Current public original and earlier additions; add substantial coverage without repeating or replacing them.","fetchedAt":"2026-11-14T07:03:17.804Z","hash":"2deb5a9baff853c04d8f1c51cf505af90de2215c3f69516d2b29af208b2d15b3","truncated":false},{"id":"current-en","title":"Current complete en canonical article","url":"https://wenbu.app/knowledge/en/bazi-solar-term-boundary.md","role":"Current public original and earlier additions; add substantial coverage without repeating or replacing them.","fetchedAt":"2026-11-14T07:03:17.815Z","hash":"5c6c16c20e690fa30c537d632b2b4ffbe63be41798ab3596d514a853dea3181e","truncated":false},{"id":"methods","title":"Wenbu · calculation conventions","url":"https://wenbu.app/methodology/","role":"First-party implementation; not evidence of predictive accuracy","fetchedAt":"2026-11-14T07:03:17.842Z","hash":"21a7f433eb1571ce23e4c4e96f09d0da54c2f9030469f4b8ecfc294a13344de5","truncated":false},{"id":"birth","title":"Wenbu · birth time and time zones","url":"https://wenbu.app/knowledge/en/birth-time-timezone.md","role":"Existing editorial and boundary examples","fetchedAt":"2026-11-14T07:03:17.846Z","hash":"010a7ce6d9b6dd003c0aa06e990ee6762b0e5df052d72d7eb0741f4d31ebfef0","truncated":false},{"id":"hko","title":"Hong Kong Observatory · calendar conversion","url":"https://www.hko.gov.hk/en/gts/time/conversion.htm","role":"Official calendar reference; not evidence of fortune-telling","fetchedAt":"2026-11-14T07:03:18.700Z","hash":"a3b1a96465876ff4bbeb5218d21009ec61cbe1da57e063fbad972a501a0f2a71","truncated":false},{"id":"lunar","title":"lunar-typescript · official source","url":"https://raw.githubusercontent.com/6tail/lunar-typescript/master/README.md","role":"Calculation implementation and conventions","fetchedAt":"2026-11-14T07:03:17.993Z","hash":"fff51c10ef109e04956ca05ecc3e3162cef7a0970b9e335505221084c60cf4f6","truncated":false},{"id":"capabilities","title":"Wenbu · versioned public capabilities","url":"https://wenbu.app/capabilities.json","role":"First-party current tool, convention and privacy contract; not external endorsement or predictive validation","fetchedAt":"2026-11-14T07:03:17.844Z","hash":"557485b2f5513f237e8258ecf9d0a1fbbf5aa19a30c726f9199bf3817e021546","truncated":false}],"previousAdditions":[{"zh":{"title":"交节当天出生：年柱和月柱到底按哪个时刻算","description":"用一张交节边界工作表，判断出生日期落在节气换柱日时年柱、月柱是否真的不确定：记录出生日期、当地钟表时间、IANA 时区和相关节气时刻，再逐柱标“已定”或“待定”。不凭日期猜柱，也不虚构历史行政区划规则。","answer":"先给结论：只看“出生在立春当天”或“出生在某个月节气当天”，无法决定年柱和月柱。按 Wenbu 的公开约定，年柱、月柱是把出生的绝对时刻与节气时刻直接比较得出的，比较时使用固定东八区标准时（UTC+08:00，不叠加历史夏令时）；日柱、时柱则默认使用所选当地钟表时间。因此真正要确定的是“出生那一刻”与“该节气那一刻”谁先谁后，而不是日期本身。请把四项信息写在同一行：出生公历日期、当地钟表时间（精确到分钟）、出生地 IANA 时区（如 Asia/Shanghai）、以及相关节气的交接时刻。若出生时刻与节气时刻的先后无法从记录中确定，就把对应柱标为“待定”，保留两种结果，不要挑一个。","answerSourceIds":["methods","birth","bazi"],"evidence":[{"claim":"Wenbu 的年柱、月柱按出生的绝对时刻与节气时刻比较，并使用固定东八区标准时，不叠加历史夏令时。","sourceId":"methods","quote":"年、月柱按出生绝对时刻与节气时刻比较，使用固定东八区标准时","kind":"fact"},{"claim":"出生时间未知时，Wenbu 不生成时柱，年柱、月柱以当地中午暂定，并在交节日提示不确定性。","sourceId":"methods","quote":"出生时间未知时不生成时柱，年、月柱以当地中午暂定，交节日会提示不确定性。","kind":"fact"},{"claim":"编辑原则：出生记录、时区与边界设置必须与结果一起保存，仅凭八个字无法复现排盘。","sourceId":"bazi","quote":"Save the date, time zone and boundary settings with the result.","kind":"editorial"}],"takeaways":["交节日的年柱、月柱取决于出生绝对时刻与节气时刻的先后，日期本身不能决定。","工作表至少要有四项：公历日期、当地钟表时间、IANA 时区、相关节气交接时刻。","记录精度不足时，把柱标为“待定”并保留两种结果，比强行选一个更诚实。","真太阳时校正只影响日柱、时柱，年柱、月柱仍按原绝对时刻比较。"],"sections":[{"heading":"为什么“当天”不足以定柱","paragraphs":["节气不是一个整天，而是一个天文时刻。二十四节气按太阳在黄道上的位置划分，每个节气对应一个具体的交接瞬间；年柱在立春交接时更换，月柱在相应的“节”交接时更换。所以同一天里，交接前出生和交接后出生可能落在不同的年柱或月柱上。把“立春当天”当成一个整体，等于把两个不同的时刻混在一起。","这也解释了为什么不能从日期反推柱。日期只给出一个区间，交接时刻才给出分界。Wenbu 的公开说明写明，年柱、月柱按出生的绝对时刻与节气时刻比较；比较用的是固定东八区标准时，不叠加历史夏令时。换句话说，先要把出生记录还原成一个绝对时刻，再与节气时刻比大小，而不是看日历上写着哪一天。"],"sourceIds":["methods","birth","bazi"]},{"heading":"边界工作表：四项输入，逐柱标注","paragraphs":["工作表的第一行写出生公历日期，第二行写当地钟表时间并注明精度（例如“约上午”“08:37 记录”），第三行写出生地 IANA 时区名称，第四行写相关节气的交接时刻。四项缺一，判断就只能停在“待定”。如果原始记录只有日期没有时间，那么年柱、月柱在交节日附近就无法确定；Wenbu 在这种情况下会以当地中午暂定年柱、月柱，并提示交节日的不确定性，这个暂定值不应被当成已确认的结果。","接着逐柱标注。先看年柱：只有当出生时刻与立春交接时刻的先后明确时，年柱才算“已定”。再看月柱：只有当出生时刻与该月“节”的交接时刻先后明确时，月柱才算“已定”。日柱、时柱属于另一层问题，它们默认按所选当地钟表时间计算，并受换日规则和真太阳时设置影响；本工作表不处理 23:00 子初换日，也不处理时区偏移与夏令时的换算细节，那些属于另外两篇指南的范围。"],"sourceIds":["methods","birth","bazi"]},{"heading":"记录精度决定结论的强度","paragraphs":["“08:37”和“早上八点多”不是同一种证据。若节气交接时刻落在记录精度覆盖的区间之外，结论是稳的；若落在区间之内，就只能写“待定”。例如记录为“约上午”，而节气交接在上午十点，那么上午早些时候与晚些时候出生会给出不同结果，此时不应二选一。保留两种可能，并在结果旁注明“出生记录精度不足”，比给出一个看似确定的柱更有用。","还要区分“计算不确定”和“解释不确定”。即使柱已经算定，传统解释是否成立仍是另一个问题；计算能按约定复现，不代表解释已经得到科学验证。工作表只解决前者：把输入、时刻和分界摆出来，让另一个人能复核。它不判断哪种解释更准，也不替读者选择流派。"],"sourceIds":["methods","bazi","birth"]},{"heading":"常见误区与边界","paragraphs":["第一个误区是把农历新年当成换年柱的界线。年柱按立春交接更换，不是按农历正月初一更换，所以春节前后出生的人尤其容易误判。第二个误区是把真太阳时校正套到年柱、月柱上。按 Wenbu 的说明，开启真太阳时后，日柱、时柱使用经度与均时差近似校正，年柱、月柱仍按原绝对时刻计算；对交节判断重复施加校正会引入新的错误。","第三个误区是凭出生地历史行政区划去猜时区。本页不提供、也不虚构历史管辖规则；需要的是出生地对应的 IANA 时区名称，以及该日期实际生效的偏移。若当地钟表时间在夏令时切换中出现跳过或重复，Wenbu 的排盘会拒绝这类模糊或不存在的输入，此时应补充明确的 UTC 偏移，而不是任选一个。节气时刻本身属于天文计算，与地方钟表调整是两回事。"],"sourceIds":["methods","birth","bazi"]}],"figure":{"title":"交节边界判断流程","caption":"从出生记录出发，判断年柱、月柱是否真的不确定。每一步都保留原始输入，便于他人复核；流程只处理年柱、月柱的节气分界，不处理换日规则与时区换算细节。","sourceIds":["methods","birth"],"steps":[{"label":"还原绝对时刻","detail":"用出生日期、当地钟表时间和出生地 IANA 时区，确定出生那一刻对应的绝对时刻；不要用现在的居住地时区替代出生地时区。"},{"label":"取得节气交接时刻","detail":"查得相关节气（年柱看立春，月柱看对应“节”）的交接时刻，作为分界点。"},{"label":"比较先后","detail":"把出生绝对时刻与节气交接时刻比大小。年柱、月柱按此比较，使用固定东八区标准时，不叠加历史夏令时。"},{"label":"逐柱标注","detail":"先后明确则标“已定”；记录精度覆盖了分界点则标“待定”，并同时保留两种结果。"},{"label":"保存记录","detail":"把日期、钟表时间、时区、节气时刻和标注一起保存，注明所用约定，便于与另一份排盘逐项对照。"}]},"table":{"title":"交节边界工作表：逐项记录与判定","columns":["项目","要记录什么","判定规则"],"rows":[["出生日期","公历日期，注明是否为原始记录","日期本身不决定柱，只用于定位相关节气"],["当地钟表时间","出生地钟表时间及精度（精确到分钟或“约上午”）","精度覆盖节气分界点时，相关柱标“待定”"],["IANA 时区","出生地时区名称，如 Asia/Shanghai","用于还原绝对时刻；不用现居地时区替代"],["节气交接时刻","年柱看立春，月柱看对应“节”的交接时刻","出生时刻早于交接则用前一柱，晚于则用后一柱"],["年柱状态","已定 / 待定","仅当与立春交接的先后明确时为“已定”"],["月柱状态","已定 / 待定","仅当与该月“节”交接的先后明确时为“已定”"],["日柱与时柱","另附换日规则与真太阳时设置","不在本表判定；默认按当地钟表时间计算"]],"sourceIds":["methods","birth","bazi"]},"example":{"title":"假设案例：立春交接日的边界工作表","intro":"以下为教学用的假设情境，不是真实个人资料，也不构成对任何人的命理判断。假设某人的出生记录写着“2 月 4 日上午”，出生地为上海，时区记为 Asia/Shanghai；当年立春交接时刻为 2 月 4 日 10:42（此为示例数值，仅用于演示流程，实际应以查得的节气时刻为准）。","steps":["第一步，写清输入：公历 2 月 4 日；钟表时间“上午”，精度不足；IANA 时区 Asia/Shanghai；立春交接 10:42。四项并列，不先猜柱。","第二步，还原绝对时刻：上海在该日期使用 UTC+08:00，于是“上午”对应一个时间区间，而不是单一时刻。年柱、月柱的比较使用固定东八区标准时，不叠加历史夏令时。","第三步，比较先后：10:42 之前的出生时刻与之后的出生时刻，年柱落在立春前后两侧；由于记录只写“上午”，这个区间跨过了分界点，年柱无法唯一确定。","第四步，逐柱标注：年柱标“待定”，并同时保留立春前、立春后两种结果；月柱同样取决于该月“节”的交接时刻，若也在区间内则一并标“待定”。","第五步，保存记录：把日期、“上午”、Asia/Shanghai、10:42 和“年柱待定”写在一起，注明这是精度不足导致的开放结论，而不是计算错误。"],"conclusion":"这个案例教的具体一点是：交节日的关键不是“哪一天”，而是“出生时刻区间是否跨过分界点”。当区间跨过时，正确产出是“待定 + 两种结果”，而不是从日期里挑一个柱。若把记录补到分钟并确认在 10:42 之前或之后，年柱才从“待定”变为“已定”。","sourceIds":["methods","birth","bazi"]},"faq":[{"question":"出生在立春当天，年柱一定按新年算吗？","answer":"不一定。年柱在立春交接时刻更换，而不是在立春这一天的零点更换。若出生时刻早于交接时刻，年柱仍属前一年；晚于交接时刻才进入新年柱。只有把出生绝对时刻与立春交接时刻比较，才能确定。","sourceIds":["methods","birth"]},{"question":"月柱是不是按农历月份换？","answer":"不是。按 Wenbu 的公开约定，月柱在相应的“节”交接时更换，比较的是出生绝对时刻与节气时刻。农历月份是另一套历法标记，不能直接当作月柱的分界。","sourceIds":["methods","bazi"]},{"question":"开启真太阳时后，年柱、月柱会跟着变吗？","answer":"不会按同一方式变。真太阳时校正作用于日柱、时柱，使用经度与均时差的近似校正；年柱、月柱仍按原绝对时刻与节气时刻比较。对交节判断重复施加校正会引入错误。","sourceIds":["methods","birth"]},{"question":"出生时间只记得日期，怎么办？","answer":"把年柱、月柱标为“待定”，不要从日期反推。Wenbu 在出生时间未知时不生成时柱，年柱、月柱以当地中午暂定，并在交节日提示不确定性；这个暂定值应被当作待核对的占位，而不是结论。","sourceIds":["methods"]},{"question":"两份排盘年柱不同，先查什么？","answer":"先核对出生日期、当地钟表时间和出生地 IANA 时区，再比较各自使用的节气交接时刻与比较约定。逐项对照，一次只改一个设置，看是哪一层导致差异，而不是先争论解释。","sourceIds":["methods","birth","bazi"]}],"glossary":[{"term":"节气交接时刻","definition":"某个节气开始的那个具体天文瞬间，是年柱、月柱更换的分界点，而不是一整天。","sourceIds":["methods","birth"]},{"term":"绝对时刻","definition":"由出生日期、当地钟表时间和出生地时区共同确定的时间点，用于与节气时刻比较。","sourceIds":["birth","methods"]},{"term":"待定","definition":"出生记录精度不足以判断出生时刻在节气分界点之前还是之后时，对相关柱的标注，需同时保留两种结果。","sourceIds":["methods"]},{"term":"固定东八区标准时","definition":"Wenbu 比较年柱、月柱与节气时刻时使用的 UTC+08:00 标准时，不叠加历史夏令时。","sourceIds":["methods"]}],"cta":{"label":"用 Wenbu 八字排盘核对一次交节边界","reason":"在排盘中填入出生日期、当地钟表时间和出生地 IANA 时区，查看年柱、月柱结果，并对照本工作表记录节气交接时刻与“已定/待定”标注；若记录精度不足，保留两种结果而不是挑一个。"}},"en":{"title":"Born on a solar-term day: which instant decides the year and month pillars","description":"A boundary-day worksheet for births on a solar-term transition: record the date, local clock time, IANA zone and solar-term instant, then mark the year and month pillars settled or open. No pillar is picked from the date alone.","answer":"Start with the conclusion: “born on the day of Li Chun” or “born on a month’s solar-term day” does not by itself decide the year or month pillar. Under Wenbu’s published conventions, the year and month pillars are produced by comparing the birth’s absolute instant with the solar-term instant, using a fixed UTC+08:00 standard time without adding historical daylight saving; the day and hour pillars default to the selected local clock. What matters is therefore which instant comes first — the birth or the solar term — not the date on the calendar. Write four items on one line: the Gregorian birth date, the local clock time to the minute, the birthplace IANA zone such as Asia/Shanghai, and the relevant solar-term instant. If the record cannot establish the order, mark the affected pillar “open” and keep both results rather than choosing one.","answerSourceIds":["methods","birth","bazi"],"evidence":[{"claim":"Wenbu compares the year and month pillars using the birth's absolute instant against the solar-term instant, on fixed UTC+08:00 without historical daylight saving.","sourceId":"methods","quote":"年、月柱按出生绝对时刻与节气时刻比较，使用固定东八区标准时","kind":"fact"},{"claim":"When the birth time is unknown, Wenbu omits the hour pillar, provisionally uses local noon for the year and month pillars, and flags uncertainty on solar-term days.","sourceId":"methods","quote":"出生时间未知时不生成时柱，年、月柱以当地中午暂定，交节日会提示不确定性。","kind":"fact"},{"claim":"Editorial principle: the date, time zone and boundary settings must be saved with the result, because eight characters alone are not reproducible.","sourceId":"bazi","quote":"Save the date, time zone and boundary settings with the result.","kind":"editorial"}],"takeaways":["On a transition day, the year and month pillars depend on whether the birth instant or the solar-term instant comes first; the date alone cannot decide.","The worksheet needs four inputs: Gregorian date, local clock time, IANA zone and the relevant solar-term instant.","When the record is too imprecise, mark the pillar open and keep both results instead of forcing a choice.","Apparent-solar-time correction affects the day and hour pillars; the year and month pillars still use the original absolute instant."],"sections":[{"heading":"Why “that day” cannot settle a pillar","paragraphs":["A solar term is not a whole day; it is an astronomical instant. The 24 solar terms divide the sun’s position along the ecliptic, and each term begins at a specific moment. The year pillar changes at the Li Chun transition, and the month pillar changes at the relevant jie term. Two births on the same date can therefore land on different year or month pillars depending on which side of the transition they fall. Treating “the day of Li Chun” as one block merges two different instants.","This is also why a pillar cannot be inferred from the date. A date gives an interval; the transition instant gives the dividing line. Wenbu’s published notes state that the year and month pillars compare the birth’s absolute instant with the solar-term instant, using fixed UTC+08:00 without adding historical daylight saving. In other words, first restore the birth record to an absolute instant, then compare it with the solar-term instant — do not read the pillar off the calendar day."],"sourceIds":["methods","birth","bazi"]},{"heading":"The boundary worksheet: four inputs, one mark per pillar","paragraphs":["Write the Gregorian birth date on the first line, the local clock time with its precision on the second (for example “about mid-morning” or “08:37 recorded”), the birthplace IANA zone name on the third, and the relevant solar-term instant on the fourth. If any of the four is missing, the judgment stops at “open.” If the original record has only a date and no time, the year and month pillars near a transition cannot be settled; in that case Wenbu provisionally uses local noon for the year and month pillars and flags uncertainty on solar-term days, and that provisional value should not be treated as confirmed.","Then mark each pillar. The year pillar is “settled” only when the order of the birth instant and the Li Chun transition is clear. The month pillar is “settled” only when the order of the birth instant and that month’s jie transition is clear. The day and hour pillars are a separate layer: they default to the selected local clock and are affected by the day-boundary rule and the apparent-solar-time setting. This worksheet does not handle the 23:00 Zi day boundary, and it does not handle offset or daylight-saving conversion details; those belong to the other two guides."],"sourceIds":["methods","birth","bazi"]},{"heading":"Record precision sets the strength of the conclusion","paragraphs":["“08:37” and “a bit after eight” are not the same kind of evidence. If the solar-term instant falls outside the interval covered by the record’s precision, the conclusion is stable; if it falls inside, the honest answer is “open.” Suppose the record says “about mid-morning” and the transition is at 10:42: an earlier and a later birth in that morning would give different results, so no single pillar should be chosen. Keeping both possibilities and noting “birth record too imprecise” is more useful than a pillar that looks certain.","Separate calculation uncertainty from interpretive uncertainty. Even when a pillar is settled, whether a traditional interpretation holds is a different question; a calculation can be reproduced by convention without the interpretation being scientifically validated. The worksheet addresses only the first: it lays out the inputs, the instants and the dividing line so another person can check them. It does not judge which interpretation is better, and it does not choose a school for the reader."],"sourceIds":["methods","bazi","birth"]},{"heading":"Common mistakes and the limits of this page","paragraphs":["The first mistake is treating Lunar New Year as the year-pillar boundary. The year pillar changes at the Li Chun transition, not at the first day of the first lunar month, so births around Spring Festival are especially easy to misjudge. The second is applying apparent-solar-time correction to the year and month pillars. Wenbu’s notes say that with the correction enabled, the day and hour pillars use an approximate longitude and equation-of-time adjustment, while the year and month pillars still use the original absolute instant; applying the correction again to the transition comparison introduces a new error.","The third mistake is guessing a time zone from historical jurisdiction. This page does not supply, and will not invent, historical administrative rules; what is needed is the birthplace’s IANA zone name and the offset actually in effect on that date. If a local clock time was skipped or repeated during a daylight-saving change, Wenbu’s chart rejects such ambiguous or nonexistent input, so supply an explicit UTC offset instead of picking one arbitrarily. The solar-term instant itself is an astronomical calculation, separate from local clock adjustments."],"sourceIds":["methods","birth","bazi"]}],"figure":{"title":"Flow for judging a solar-term boundary","caption":"Starting from the birth record, decide whether the year and month pillars are genuinely uncertain. Each step keeps the original inputs so another person can check them; the flow covers only the solar-term boundary for the year and month pillars, not the day-boundary rule or offset conversion details.","sourceIds":["methods","birth"],"steps":[{"label":"Restore the absolute instant","detail":"Use the birth date, local clock time and birthplace IANA zone to fix the absolute instant of birth; do not substitute the current residence zone for the birthplace zone."},{"label":"Obtain the solar-term instant","detail":"Look up the relevant term’s transition instant — Li Chun for the year pillar, the relevant jie for the month pillar — as the dividing point."},{"label":"Compare the order","detail":"Compare the birth instant with the transition instant. The year and month pillars use this comparison on fixed UTC+08:00 without historical daylight saving."},{"label":"Mark each pillar","detail":"If the order is clear, mark “settled”; if the record’s precision spans the dividing point, mark “open” and keep both results."},{"label":"Save the record","detail":"Save the date, clock time, zone, solar-term instant and marks together, noting the conventions used, so another chart can be compared item by item."}]},"table":{"title":"Solar-term boundary worksheet: what to record and how to judge","columns":["Item","What to record","Decision rule"],"rows":[["Birth date","Gregorian date, noting whether it is the original record","The date alone does not decide a pillar; it locates the relevant term"],["Local clock time","Birthplace clock time and precision (to the minute, or “about mid-morning”)","If precision spans the transition, mark the affected pillar open"],["IANA zone","Birthplace zone name, e.g. Asia/Shanghai","Used to restore the absolute instant; do not substitute the current residence zone"],["Solar-term instant","Li Chun for the year pillar; the relevant jie for the month pillar","Birth before the transition uses the earlier pillar; after it uses the later one"],["Year pillar status","Settled / open","Settled only when the order against the Li Chun transition is clear"],["Month pillar status","Settled / open","Settled only when the order against that month’s jie transition is clear"],["Day and hour pillars","Attach the day-boundary rule and solar-time setting separately","Not judged here; they default to the local clock"]],"sourceIds":["methods","birth","bazi"]},"example":{"title":"Hypothetical case: a boundary worksheet for a Li Chun transition day","intro":"The following is a teaching scenario, not a real person’s data, and it makes no claim about anyone’s fate. Suppose a birth record says “the morning of February 4,” with Shanghai as the birthplace and Asia/Shanghai as the zone; suppose that year’s Li Chun transition was at 10:42 on February 4 (an illustrative value used only to demonstrate the process — the actual instant should be looked up).","steps":["Step one, write the inputs: Gregorian February 4; clock time “morning,” precision insufficient; IANA zone Asia/Shanghai; Li Chun transition 10:42. List all four before guessing any pillar.","Step two, restore the absolute instant: Shanghai used UTC+08:00 on that date, so “morning” corresponds to an interval, not a single instant. The year and month comparison uses fixed UTC+08:00 without historical daylight saving.","Step three, compare the order: a birth before 10:42 and a birth after it fall on opposite sides of Li Chun, so because the record says only “morning,” the interval crosses the dividing point and the year pillar cannot be uniquely determined.","Step four, mark each pillar: mark the year pillar “open” and keep both the pre-Li Chun and post-Li Chun results; the month pillar likewise depends on that month’s jie transition, and if that also falls inside the interval, mark it open too.","Step five, save the record: write the date, “morning,” Asia/Shanghai, 10:42 and “year pillar open” together, noting that this is an open conclusion caused by insufficient precision, not a calculation error."],"conclusion":"The specific lesson is that on a transition day the question is not “which day” but “does the birth-time interval cross the dividing point.” When it does, the correct output is “open plus both results,” not a pillar picked from the date. Only when the record is refined to the minute and confirmed to fall before or after 10:42 does the year pillar move from open to settled.","sourceIds":["methods","birth","bazi"]},"faq":[{"question":"If I was born on the day of Li Chun, is the year pillar always the new year’s?","answer":"Not necessarily. The year pillar changes at the Li Chun transition instant, not at midnight of that date. A birth before the transition still belongs to the previous year pillar; only a birth after it enters the new one. Comparing the birth’s absolute instant with the Li Chun instant is what settles it.","sourceIds":["methods","birth"]},{"question":"Does the month pillar change with the lunar month?","answer":"No. Under Wenbu’s published conventions, the month pillar changes at the relevant jie transition, comparing the birth’s absolute instant with the solar-term instant. The lunar month is a different calendar label and cannot serve directly as the month-pillar boundary.","sourceIds":["methods","bazi"]},{"question":"Does enabling apparent solar time change the year and month pillars too?","answer":"Not in the same way. The apparent-solar-time correction applies to the day and hour pillars through an approximate longitude and equation-of-time adjustment; the year and month pillars still compare the original absolute instant with the solar-term instant. Applying the correction again to the transition comparison introduces error.","sourceIds":["methods","birth"]},{"question":"What if I only remember the date, not the time?","answer":"Mark the year and month pillars open; do not infer them from the date. When the birth time is unknown, Wenbu omits the hour pillar, provisionally uses local noon for the year and month pillars, and flags uncertainty on solar-term days; treat that provisional value as a placeholder to be checked, not a conclusion.","sourceIds":["methods"]},{"question":"Two charts disagree on the year pillar — what should I check first?","answer":"Check the birth date, local clock time and birthplace IANA zone first, then compare the solar-term instant and comparison convention each chart uses. Compare item by item and change one setting at a time to see which layer causes the difference, rather than arguing about interpretation first.","sourceIds":["methods","birth","bazi"]}],"glossary":[{"term":"Solar-term transition instant","definition":"The specific astronomical moment at which a solar term begins; it is the boundary for changing the year and month pillars, not a whole day.","sourceIds":["methods","birth"]},{"term":"Absolute instant","definition":"The point in time fixed by the birth date, local clock time and birthplace zone, used for comparison with the solar-term instant.","sourceIds":["birth","methods"]},{"term":"Open","definition":"A mark for a pillar when the birth record’s precision cannot establish whether the birth came before or after the solar-term boundary; both results must be kept.","sourceIds":["methods"]},{"term":"Fixed UTC+08:00 standard time","definition":"The UTC+08:00 standard used by Wenbu when comparing the year and month pillars with solar-term instants, without adding historical daylight saving.","sourceIds":["methods"]}],"cta":{"label":"Check one solar-term boundary in Wenbu’s BaZi chart","reason":"Enter the birth date, local clock time and birthplace IANA zone in the chart, read the year and month pillars, and compare them with the solar-term instant and the settled/open marks on this worksheet; if the record is too imprecise, keep both results rather than choosing one."}},"topic":{"id":"bazi-solar-term-boundary","slug":"bazi-solar-term-boundary","category":"learn","mode":"new","tool":"bazi","zh":"交节当天出生：年柱和月柱到底按哪个时刻算","en":"Born on a solar-term day: which instant decides the year and month pillars","task":"Help a reader whose birth date falls on a solar-term transition day check whether the year or month pillar is genuinely uncertain, and record the exact instant and time zone needed to settle it.","unique":"A boundary-day worksheet: list the birth date, local clock time, IANA zone and the relevant solar-term instant, then mark each pillar as settled or open. Distinct from the existing time-zone guide, which covers offsets and daylight saving, and from the day-boundary guide, which covers the 23:00 Zi rule. Explicitly refuses to pick a pillar from the date alone and does not invent historical jurisdiction rules.","sources":["bazi","birth","methods","lunar"],"priority":74,"search":{"pillar":"bazi-calendar","intent":"solve","zh":["交节出生八字","立春当天出生年柱","节气换月柱","出生在节气交界"],"en":["born on solar term BaZi","Li Chun birth year pillar","solar term month pillar boundary","BaZi boundary date"],"basis":"research_hypothesis"}},"revision":"8dc013a096c3ce44fbe7b20d34974fb5c62d6f24d197a74554f103c84ee527fe","updatedAt":"2026-11-01T13:02:31.515Z","sources":[{"id":"bazi","title":"Wenbu · BaZi guide","url":"https://wenbu.app/knowledge/en/bazi-basics.md","role":"Existing editorial and reproducible chart conventions","fetchedAt":"2026-11-01T13:00:34.984Z","hash":"2a711b520e145fb46c36e647469f9d393a7522bdeb1583c15d10be8e4b692b3c","truncated":false},{"id":"birth","title":"Wenbu · birth time and time zones","url":"https://wenbu.app/knowledge/en/birth-time-timezone.md","role":"Existing editorial and boundary examples","fetchedAt":"2026-11-01T13:00:34.988Z","hash":"a73bf46adcb94f9c6b53c70a8719ef9fe0e8fa1dde2c3a587b7bca84636516f2","truncated":false},{"id":"methods","title":"Wenbu · calculation conventions","url":"https://wenbu.app/methodology/","role":"First-party implementation; not evidence of predictive accuracy","fetchedAt":"2026-11-01T13:00:34.984Z","hash":"5452dbc076e1c31aa334fa49949d682ad7851e75a5cf9396b6682530b30f0f0c","truncated":false},{"id":"lunar","title":"lunar-typescript · official source","url":"https://raw.githubusercontent.com/6tail/lunar-typescript/master/README.md","role":"Calculation implementation and conventions","fetchedAt":"2026-11-01T13:00:34.984Z","hash":"3d6c98fef4e98fb7b1dfcb24d29e4d3515d931fcf87b78d6a01b4a082739d98c","truncated":false}]}]}