{"version":1,"scope":"full","truncated":false,"id":"editorial-learn-bazi-hour-stem-five-rats","url":"https://wenbu.app/en/learn/bazi-hour-stem-five-rats/","locale":"en","revision":"f9f723474ab71e613b5923471ef264bcd1bdf40afd2a022dec190d083f92d4ff","updated":"2026-11-13T01:18:15.168Z","content":"# Derive the hour stem with the five-rat rule: a twelve-branch worksheet\n\nUse the five-rat rule to derive hour stems from one day stem: a fillable twelve-branch worksheet, a hypothetical practice case, and a check against a returned example chart.\n\nUpdated: 2026-11-06 · Wenbu AI-assisted editorial\n\nTake the day stem, use the five-rat rule to fix the stem paired with the Zi hour, then run the ten stems in order across the twelve branches. For a Xin day: Bing-Xin days start at Wu Zi, so Zi is Wu, Chou is Ji, Yin is Geng, Mao is Xin, Chen is Ren, Si is Gui, Wu is Jia, Wei is Yi, Shen is Bing, You is Ding, Xu is Wu and Hai is Ji. Check the result against the returned example chart: 2005-12-23 08:37 in Asia/Shanghai falls in the Chen interval, the day stem is Xin, the derivation gives Ren Chen, and the returned hour pillar is also Ren Chen. This confirms only that your lookup matches the calculation under those settings; it establishes no interpretation. One caveat: for 23:00–23:59, Wenbu's default 00:00 day boundary keeps the current day pillar but takes the hour stem from the library's next-day convention, so label that case separately.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- The five-rat rule needs only the day stem to fix the Zi-hour stem; the other eleven hours follow in sequence.\n\n- A twelve-cell worksheet makes each step visible so it can be checked cell by cell, not just read off eight characters.\n\n- Confirm date, time zone and day-boundary settings before comparing hour pillars, or a mismatch may come from settings rather than the rule.\n\n- For 23:00–23:59, the default day boundary keeps the current day pillar but takes the hour stem from the next-day convention, so label it separately.\n\n## From day stem to twelve hour stems\n\n1. **Fix the inputs** — Record the Gregorian date, local clock time, time zone, day-boundary setting and whether true solar time is enabled.\n\n2. **Read the day stem** — Take the stem from the day pillar, for example Xin from a Xin Si day, computed under the same settings.\n\n3. **Set the Zi-hour stem** — Apply the five-rat rule to find the stem paired with Zi; Bing-Xin days give Wu Zi.\n\n4. **Run the twelve cells** — Fill Chou through Hai in stem order; adjacent cells must hold adjacent stems.\n\n5. **Flag late Zi** — If the time is 23:00–23:59, mark that cell and read the returned hour stem or compare day-boundary settings.\n\n6. **Compare with the returned result** — Match your derived hour pillar against the tool's; if they differ, check settings first.\n\nThe flow breaks the five-rat rule into checkable steps: fix the inputs, set the Zi-hour stem, run twelve cells, flag any late-Zi case, then compare with the returned hour pillar. If any step disagrees, return to the input settings rather than skipping the check.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## What the five-rat rule actually does\n\nThe five-rat rule is a traditional lookup: the day stem determines which heavenly stem is paired with the Zi hour, and from there the ten stems are assigned in order to Chou, Yin, Mao and on through Hai. The mnemonic groups the ten day stems into five pairs, each with one starting stem, so you memorise five lines rather than sixty combinations one by one. It is a fixed step in chart construction, a traditional convention rather than a claim about a person's fate.\n\nBefore using it, confirm the day stem, which depends on the day pillar. The day pillar in turn depends on the recorded time, time zone and day-boundary setting. Wenbu's published notes state that the day and hour pillars use the selected local clock time by default, with a 00:00 day change. Fix those inputs first, or the day stem itself may differ and the rule cannot be checked.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Filling the twelve-cell worksheet\n\nLay the twelve branches across the top in order: Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai. Put the day stem at the left. The first cell holds the Zi-hour stem given directly by the rule; each later cell takes the next stem in the ten-stem cycle, wrapping from Gui back to Jia. Twelve cells therefore run slightly past one full cycle, which is expected and needs no correction.\n\nRun two self-checks afterwards. Adjacent cells must hold adjacent stems, so a jump means a copying error. The Zi and Wu cells sit six positions apart, which gives a second cross-check. The worksheet's value is that it makes the day-to-hour derivation explicit, so another reader can recompute every step. The table below gives the full twelve cells for a Xin day as a reference and leaves one blank row for you to fill with a different day stem.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Checking the derivation against the example chart\n\nWenbu's introductory guide gives a fixed teaching example: 2005-12-23 08:37, Asia/Shanghai, civil clock, midnight day boundary, no solar-time correction, with pillars Yi You, Wu Zi, Xin Si and Ren Chen. It is not a user profile but a reproducible teaching record, which makes it suitable for testing whether your five-rat derivation matches the tool.\n\nCheck in this order. First confirm the time falls in the Chen interval, 07:00 to before 09:00. Then take Xin from the day pillar Xin Si. Apply Bing-Xin days start at Wu Zi and count to Chen, which gives Ren Chen. Finally compare with the returned hour pillar, also Ren Chen. Agreement shows your derivation matches the calculation under these settings. If it does not, check time zone, day boundary and hour edges before doubting the rule.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Flag the late-Zi exception separately\n\nThe twelve-cell worksheet uses the ordinary five-rat starting rule, but Wenbu's default 00:00 day boundary treats 23:00–23:59 specially: the day pillar stays with the current day, while the hour stem follows the library's next-day convention. So for someone born at 23:30, deriving the Zi-hour stem from the current day stem by the plain rule may give a different hour stem than the tool returns. The rule is not wrong; the day-boundary convention is at work.\n\nThe fix is simple. For a late-Zi time, read the returned hour pillar first, or switch to the 23:00 Zi-start boundary and compare the two returned results, and mark that cell on the worksheet as a late-Zi case. The published notes also recommend comparing results under different settings near a day change or hour boundary. This is not a claim that one convention is correct; it is a reminder to record settings alongside the derivation.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Keep derivation separate from interpretation\n\nDeriving an hour stem belongs to the calendar layer, which can be recomputed from a date, a time zone and stated rules. What an hour pillar means, and how to read it, belongs to the traditional symbolic layer. Wenbu's notes keep the two apart: a calculation can be reproduced by convention without its interpretation being scientifically validated. A successful worksheet check shows you can apply the lookup; it is not evidence for any prediction or for health or financial claims.\n\nA second confusion treats the hour pillar as a complete description of a person. The guide notes that stem-branch combinations are finite and an hour pillar usually spans a two-hour interval, so identical symbols do not record someone's circumstances or choices. Treating the derivation as a checkable record rather than a conclusion is the more careful way to use the worksheet.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Five-rat twelve-branch worksheet (Xin day filled; last row blank for practice)\n\n| Day stem | Zi to Si | Wu to Hai | Check point |\n| --- | --- | --- | --- |\n| Xin (filled) | Zi Wu, Chou Ji, Yin Geng, Mao Xin, Chen Ren, Si Gui | Wu Jia, Wei Yi, Shen Bing, You Ding, Xu Wu, Hai Ji | Chen cell is Ren Chen, matching the example chart |\n| Jia-Ji (start reference) | Zi Jia, Chou Yi, Yin Bing, Mao Ding, Chen Wu, Si Ji | Wu Geng, Wei Xin, Shen Ren, You Gui, Xu Jia, Hai Yi | Jia-Ji days start at Jia Zi |\n| Bing-Xin (start reference) | Zi Wu, Chou Ji, Yin Geng, Mao Xin, Chen Ren, Si Gui | Wu Jia, Wei Yi, Shen Bing, You Ding, Xu Wu, Hai Ji | Bing-Xin days start at Wu Zi |\n| (your day stem) | Zi, Chou, Yin, Mao, Chen, Si | Wu, Wei, Shen, You, Xu, Hai | Fill the Zi cell first, then run in order |\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Hypothetical practice: twelve cells for a Xin day, checked against the example chart\n\nThe following is a hypothetical practice situation for demonstrating the worksheet; it does not describe any real person. Suppose you hold a record whose day stem is Xin and whose birth time falls in the Chen interval, and you want to derive the hour stem yourself before comparing with the returned example chart.\n\n1. First, apply the rule to the starting value: Bing-Xin days start at Wu Zi, so the Zi-hour stem is Wu.\n\n2. Second, run the sequence: Zi Wu, Chou Ji, Yin Geng, Mao Xin, Chen Ren, Si Gui, Wu Jia, Wei Yi, Shen Bing, You Ding, Xu Wu, Hai Ji.\n\n3. Third, confirm the interval: the example's 08:37 falls in Chen, 07:00 to before 09:00, so take the Chen cell and get Ren Chen.\n\n4. Fourth, compare with the chart Wenbu returns: pillars Yi You, Wu Zi, Xin Si and Ren Chen, day stem Xin, hour pillar Ren Chen, matching the derivation.\n\n5. Fifth, record the settings: civil clock, Asia/Shanghai, midnight day boundary, no solar-time correction, so another reader can recompute the same record. If the time were 23:30, the late-Zi exception would apply and this table could not be used directly.\n\nThe derivation matches the returned hour pillar, which shows you applied the five-rat rule correctly under these settings. It validates only the lookup process, not any reading of a person; with a different day boundary or solar-time setting, take the day stem again and redo the sequence.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## FAQ\n\n### Must the hour stem always be derived with the five-rat rule?\n\nThe five-rat rule is a common traditional method that fixes the Zi-hour stem from the day stem and then runs the twelve hours in order. The ten day stems fall into five groups, each with one starting stem, and with the twelve branches these yield the sixty hour pillars, which makes hand-checking practical. Schools may differ on day-boundary and solar-time settings, but the rule itself is a lookup step, not a judgment about a person's fate.\n\n[Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n### Why does my hour stem differ from the tool's?\n\nCompare inputs before doubting the rule: Gregorian date, local clock time, time zone, day-boundary setting and the true-solar-time option. Wenbu defaults to a 00:00 day change and also offers 23:00 Zi-start; enabling true solar time applies an approximate correction to the day and hour pillars. In particular, for 23:00–23:59 the default boundary keeps the current day pillar but takes the hour stem from the next-day convention, so read the returned hour stem or switch the boundary and compare both results.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n### Can I derive an hour pillar if the birth time is unknown?\n\nNot reliably. Wenbu's published notes state that no hour pillar is generated when the birth time is unknown, and the year and month pillars are provisionally set to local noon with an uncertainty note. Without a time there is no hour interval, so there is no cell to fill; leave it blank rather than guessing an hour and applying the rule.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n### If the check matches, does that validate an interpretation?\n\nNo. A match shows only that you applied the lookup correctly under the given settings, which is the calendar layer. Wenbu separates calculation from interpretation: a calculation can be reproduced by convention without its interpretation being scientifically validated. Traditional meanings, inferences and your own circumstances should be kept apart.\n\n[Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Glossary\n\n- **Five-rat rule**: A traditional lookup that fixes the stem paired with the Zi (rat) hour from the day stem, then assigns the remaining hour stems in sequence. [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- **Day stem**: The heavenly stem of the day pillar, also called the Day Master; it is the only input to the five-rat rule and the reference for Ten Gods relations. [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- **Hour interval**: The two-hour span assigned to each branch, such as Chen from 07:00 to before 09:00; the birth time determines which cell applies. [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n- **Day-boundary setting**: The convention for when a day begins; Wenbu defaults to 00:00 and also offers a 23:00 Zi-start, which affects which day pillar a moment belongs to and the hour stem for late Zi. [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Evidence notes\n\n- Wenbu's example chart lists the four pillars Yi You, Wu Zi, Xin Si and Ren Chen, with Xin as the day stem and Ren Chen as the hour pillar. — “乙酉 / 戊子 / 辛巳 / 壬辰” (fact); [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- The example's time falls in the Chen interval, running from 07:00 to before 09:00. — “The time falls in the Chen interval, from 07:00 to before 09:00.” (fact); [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- By default the day and hour pillars use the selected local clock time, so day-boundary and solar-time settings can change the result. — “日、时柱默认使用所选当地钟表时间” (fact); [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Sources\n\n- [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) — Existing editorial and reproducible chart conventions; fetched 2026-11-06T02:30:33.877Z; complete response\n\n- [Wenbu · calculation conventions](https://wenbu.app/methodology/) — First-party implementation; not evidence of predictive accuracy; fetched 2026-11-06T02:30:33.680Z; complete response\n\n- [lunar-typescript · official source](https://raw.githubusercontent.com/6tail/lunar-typescript/master/README.md) — Calculation implementation and conventions; fetched 2026-11-06T02:30:33.841Z; complete response\n\n[Generate a chart from the example record and check your hour-stem derivation cell by cell](https://wenbu.app/en/bazi/)\n\n# Can an hour pillar identify the BaZi day stem? Check a Ren Chen record\n\nWork backwards from a copied Ren Chen hour pillar. Compare three practice charts and see which transcription errors the Five Rats rule can detect.\n\nUpdated: 2026-11-13 · Wenbu AI-assisted editorial\n\nIf the copied hour pillar is Ren Chen and the chart used the ordinary Chen hour under a verified convention, the day stem can be Bing or Xin. Count back four stems from Ren to Wu. Both Bing and Xin start from Wu Zi in the Five Rats table, so both give Ren Chen at Chen. Use a trusted date or the original chart to choose between them.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- Check the branch and the validity of the copied pair before reversing the rule.\n\n- Step back from Ren to Wu and retain both Bing and Xin.\n\n- Look up the date or the original day pillar to resolve the candidates.\n\n## Work back from the hour pillar\n\n1. **Verify the hour** — In this exercise, 08:37 belongs to Chen.\n\n2. **Count back four** — Go from Ren through Xin, Geng and Ji to Wu.\n\n3. **Keep both day stems** — Read Bing and Xin in the starting table, then seek independent date evidence.\n\nUse the verified hour branch to count backwards, then check the starting group.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Check the two copied characters before reversing the rule\n\nSuppose the notebook lists 08:37 at the birthplace and Ren Chen, but the day pillar is missing. Check that the original chart used local civil time without solar correction and that it put the time in Chen. If another copy says Gui Si, check the original time, branch and settings. Gui Si can occur as a pair, but Si does not match the recorded hour under these settings.\n\nSome transcriptions can be ruled out even without the clock. Gui Chen does not occur in the ordinary stem and branch pairing. Under the five starting rows in the worksheet, the possible stems at Chen are Jia, Bing, Wu, Geng and Ren. Keep the questionable copy and look for the source chart instead of quietly replacing a character.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Read the rule backwards and preserve both candidates\n\nFrom Zi, the steps are Chou, Yin, Mao and Chen. Move back four places from Ren through Xin, Geng and Ji to Wu. The worksheet gives Bing and Xin as the two days that start at Wu Zi. A copied Yi day stem and a Ren Chen hour pillar cannot both fit this same ordinary daytime calculation. That mismatch is a reason to check the records.\n\nFor a direct calculation, use 08:37 and Asia/Shanghai. Set rollover to midnight and leave solar correction off. On April 2, 2024 the day pillar is Bing Shen. On April 7 it is Xin Chou. Both hour pillars are Ren Chen. On April 1 the day is Yi Wei and the hour is Geng Chen. These are three practice charts, each with its own known date.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Three practice dates and one impossible transcription\n\n| Date or record | Day pillar | Hour pillar | What it shows |\n| --- | --- | --- | --- |\n| 2024-04-02 | Bing Shen | Ren Chen | Fits the Bing candidate |\n| 2024-04-07 | Xin Chou | Ren Chen | Fits the Xin candidate |\n| 2024-04-01 | Yi Wei | Geng Chen | Yi gives a different Chen-hour stem |\n| Copied Gui Chen | Unknown | Gui Chen | Check the original transcription |\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Audit a fictional note that only gives Ren Chen\n\nThe fictional note also gives 08:37 and a verified civil-clock convention.\n\n1. Set Asia/Shanghai, midnight rollover and solar correction off for the exercise.\n\n2. Use the four steps from Chen back to Zi to find Wu Zi.\n\n3. Run April 2 and April 7. Read the two different day pillars and the shared Ren Chen hour pillar.\n\n4. If another line in the note says Yi, run April 1 to see the contrasting Geng Chen result.\n\nRecord Bing or Xin as the two possible day stems. Leave the day pillar open until you can verify the date.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## FAQ\n\n### Can I get the entire day pillar from Ren Chen?\n\nThe reverse check returns two possible day stems. It supplies no day branch. An independently known date or the source chart is needed for the complete day pillar.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n### Can I use the same example at 23:30?\n\nCheck the late Zi rules in the original chart before applying the worksheet. The day and hour stems around rollover follow the stated convention, which is outside this daytime example.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n### What should I change first if the clock and branch disagree?\n\nKeep the original note. Check the chart's clock convention, time zone, correction settings and column labels. Leave the reverse check unresolved while those inputs remain uncertain.\n\n[Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Glossary\n\n- **Zi starting stem**: The stem assigned to Zi for a particular day-stem group. The next stems can be counted forward from it. [Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- **Day-stem group**: The pair of day stems that share one starting stem under the Five Rats rule. [Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) · [Wenbu · calculation conventions](https://wenbu.app/methodology/) · [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n## Evidence notes\n\n- Bing and Xin share the Wu Zi starting pair in the existing worksheet. — “Bing-Xin days start at Wu Zi” (fact); [Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md)\n\n- The beginner guide gives Xin Si as the day pillar and Ren Chen as the hour pillar in one example. — “Xin Si and Ren Chen” (fact); [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md)\n\n- The public method calls for checking settings near boundaries. The worked example keeps its ordinary daytime input fixed. — “临近换日或时辰边界时” (fact); [Wenbu · calculation conventions](https://wenbu.app/methodology/)\n\n## Sources\n\n- [Current complete zh canonical article](https://wenbu.app/knowledge/zh/bazi-hour-stem-five-rats.md) — Current public original and earlier additions; add substantial coverage without repeating or replacing them.; fetched 2026-11-13T01:04:54.603Z; complete response\n\n- [Current complete en canonical article](https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md) — Current public original and earlier additions; add substantial coverage without repeating or replacing them.; fetched 2026-11-13T01:04:54.636Z; complete response\n\n- [Wenbu · calculation conventions](https://wenbu.app/methodology/) — First-party implementation; not evidence of predictive accuracy; fetched 2026-11-13T01:04:54.671Z; complete response\n\n- [Wenbu · BaZi guide](https://wenbu.app/knowledge/en/bazi-basics.md) — Existing editorial and reproducible chart conventions; fetched 2026-11-13T01:04:54.697Z; complete response\n\n- [lunar-typescript · official source](https://raw.githubusercontent.com/6tail/lunar-typescript/master/README.md) — Calculation implementation and conventions; fetched 2026-11-13T01:04:54.793Z; complete response\n\n[Compare the Bing and Xin examples in the BaZi tool](https://wenbu.app/en/bazi/)","edition":{"title":"Can an hour pillar identify the BaZi day stem? Check a Ren Chen record","description":"Work backwards from a copied Ren Chen hour pillar. Compare three practice charts and see which transcription errors the Five Rats rule can detect.","answer":"If the copied hour pillar is Ren Chen and the chart used the ordinary Chen hour under a verified convention, the day stem can be Bing or Xin. Count back four stems from Ren to Wu. Both Bing and Xin start from Wu Zi in the Five Rats table, so both give Ren Chen at Chen. Use a trusted date or the original chart to choose between them.","answerSourceIds":["current-en","methods","bazi"],"evidence":[{"claim":"Bing and Xin share the Wu Zi starting pair in the existing worksheet.","sourceId":"current-en","quote":"Bing-Xin days start at Wu Zi","kind":"fact"},{"claim":"The beginner guide gives Xin Si as the day pillar and Ren Chen as the hour pillar in one example.","sourceId":"bazi","quote":"Xin Si and Ren Chen","kind":"fact"},{"claim":"The public method calls for checking settings near boundaries. The worked example keeps its ordinary daytime input fixed.","sourceId":"methods","quote":"临近换日或时辰边界时","kind":"fact"}],"takeaways":["Check the branch and the validity of the copied pair before reversing the rule.","Step back from Ren to Wu and retain both Bing and Xin.","Look up the date or the original day pillar to resolve the candidates."],"sections":[{"heading":"Check the two copied characters before reversing the rule","paragraphs":["Suppose the notebook lists 08:37 at the birthplace and Ren Chen, but the day pillar is missing. Check that the original chart used local civil time without solar correction and that it put the time in Chen. If another copy says Gui Si, check the original time, branch and settings. Gui Si can occur as a pair, but Si does not match the recorded hour under these settings.","Some transcriptions can be ruled out even without the clock. Gui Chen does not occur in the ordinary stem and branch pairing. Under the five starting rows in the worksheet, the possible stems at Chen are Jia, Bing, Wu, Geng and Ren. Keep the questionable copy and look for the source chart instead of quietly replacing a character."],"sourceIds":["current-en","methods","bazi"]},{"heading":"Read the rule backwards and preserve both candidates","paragraphs":["From Zi, the steps are Chou, Yin, Mao and Chen. Move back four places from Ren through Xin, Geng and Ji to Wu. The worksheet gives Bing and Xin as the two days that start at Wu Zi. A copied Yi day stem and a Ren Chen hour pillar cannot both fit this same ordinary daytime calculation. That mismatch is a reason to check the records.","For a direct calculation, use 08:37 and Asia/Shanghai. Set rollover to midnight and leave solar correction off. On April 2, 2024 the day pillar is Bing Shen. On April 7 it is Xin Chou. Both hour pillars are Ren Chen. On April 1 the day is Yi Wei and the hour is Geng Chen. These are three practice charts, each with its own known date."],"sourceIds":["current-en","methods","bazi"]}],"figure":{"title":"Work back from the hour pillar","caption":"Use the verified hour branch to count backwards, then check the starting group.","sourceIds":["current-en","methods","bazi"],"steps":[{"label":"Verify the hour","detail":"In this exercise, 08:37 belongs to Chen."},{"label":"Count back four","detail":"Go from Ren through Xin, Geng and Ji to Wu."},{"label":"Keep both day stems","detail":"Read Bing and Xin in the starting table, then seek independent date evidence."}]},"table":{"title":"Three practice dates and one impossible transcription","columns":["Date or record","Day pillar","Hour pillar","What it shows"],"rows":[["2024-04-02","Bing Shen","Ren Chen","Fits the Bing candidate"],["2024-04-07","Xin Chou","Ren Chen","Fits the Xin candidate"],["2024-04-01","Yi Wei","Geng Chen","Yi gives a different Chen-hour stem"],["Copied Gui Chen","Unknown","Gui Chen","Check the original transcription"]],"sourceIds":["current-en","methods","bazi"]},"example":{"title":"Audit a fictional note that only gives Ren Chen","intro":"The fictional note also gives 08:37 and a verified civil-clock convention.","steps":["Set Asia/Shanghai, midnight rollover and solar correction off for the exercise.","Use the four steps from Chen back to Zi to find Wu Zi.","Run April 2 and April 7. Read the two different day pillars and the shared Ren Chen hour pillar.","If another line in the note says Yi, run April 1 to see the contrasting Geng Chen result."],"conclusion":"Record Bing or Xin as the two possible day stems. Leave the day pillar open until you can verify the date.","sourceIds":["current-en","methods","bazi"]},"faq":[{"question":"Can I get the entire day pillar from Ren Chen?","answer":"The reverse check returns two possible day stems. It supplies no day branch. An independently known date or the source chart is needed for the complete day pillar.","sourceIds":["current-en","methods","bazi"]},{"question":"Can I use the same example at 23:30?","answer":"Check the late Zi rules in the original chart before applying the worksheet. The day and hour stems around rollover follow the stated convention, which is outside this daytime example.","sourceIds":["current-en","methods","bazi"]},{"question":"What should I change first if the clock and branch disagree?","answer":"Keep the original note. Check the chart's clock convention, time zone, correction settings and column labels. Leave the reverse check unresolved while those inputs remain uncertain.","sourceIds":["current-en","methods","bazi"]}],"glossary":[{"term":"Zi starting stem","definition":"The stem assigned to Zi for a particular day-stem group. The next stems can be counted forward from it.","sourceIds":["current-en","methods","bazi"]},{"term":"Day-stem group","definition":"The pair of day stems that share one starting stem under the Five Rats rule.","sourceIds":["current-en","methods","bazi"]}],"cta":{"label":"Compare the Bing and Xin examples in the BaZi tool","reason":"Run both dates with the same settings. Read the top character of the day pillar and then compare the complete hour pillars."}},"editionScope":"addition","sources":[{"id":"current-zh","title":"Current complete zh canonical article","url":"https://wenbu.app/knowledge/zh/bazi-hour-stem-five-rats.md","role":"Current public original and earlier additions; add substantial coverage without repeating or replacing them.","fetchedAt":"2026-11-13T01:04:54.603Z","hash":"95fa4deabb2abdb364fe1319ad990d6ec11501287da64f469c7e779d7caf4dbd","truncated":false},{"id":"current-en","title":"Current complete en canonical article","url":"https://wenbu.app/knowledge/en/bazi-hour-stem-five-rats.md","role":"Current public original and earlier additions; add substantial coverage without repeating or replacing them.","fetchedAt":"2026-11-13T01:04:54.636Z","hash":"7a3124cd9969e83cd5b98bc5f8c751503279ded4e7be866a44a961c3c4316942","truncated":false},{"id":"methods","title":"Wenbu · calculation conventions","url":"https://wenbu.app/methodology/","role":"First-party implementation; not evidence of predictive accuracy","fetchedAt":"2026-11-13T01:04:54.671Z","hash":"21a7f433eb1571ce23e4c4e96f09d0da54c2f9030469f4b8ecfc294a13344de5","truncated":false},{"id":"bazi","title":"Wenbu · BaZi guide","url":"https://wenbu.app/knowledge/en/bazi-basics.md","role":"Existing editorial and reproducible chart conventions","fetchedAt":"2026-11-13T01:04:54.697Z","hash":"2a711b520e145fb46c36e647469f9d393a7522bdeb1583c15d10be8e4b692b3c","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":"2026-11-13T01:04:54.793Z","hash":"fff51c10ef109e04956ca05ecc3e3162cef7a0970b9e335505221084c60cf4f6","truncated":false}],"previousAdditions":[{"zh":{"title":"时柱天干怎么推：五鼠遁口诀与十二地支对照","description":"从日干出发，用五鼠遁定子时天干并顺排十二时辰：一张可填写的十二地支工作表、一个虚构练习案例，以及与工具返回示例盘的逐项核对。","answer":"先取日干，按五鼠遁口诀定出子时所配天干，再沿十天干顺序把子、丑、寅直到亥十二格依次排满。以辛日为例：丙辛日起戊子，于是子戊、丑己、寅庚、卯辛、辰壬、巳癸、午甲、未乙、申丙、酉丁、戌戊、亥己。得到时干后，用工具返回的示例盘核对：2005-12-23 08:37（Asia/Shanghai）落在辰时，日干为辛，推导得壬辰，与返回的壬辰时柱一致。这一步只验证推导是否符合这套设置下的计算规则，不说明任何命理判断成立。另需注意：23:00 至 23:59 的晚子时，Wenbu 默认 00:00 换日会保留当日日柱，但时干取库的次日约定，需单独标注。","answerSourceIds":["bazi","methods"],"evidence":[{"claim":"Wenbu 的示例盘给出乙酉、戊子、辛巳、壬辰四柱，日干为辛，时柱为壬辰。","sourceId":"bazi","quote":"乙酉 / 戊子 / 辛巳 / 壬辰","kind":"fact"},{"claim":"该示例的时辰落在辰时区间，即 07:00 到 09:00 之前。","sourceId":"bazi","quote":"The time falls in the Chen interval, from 07:00 to before 09:00.","kind":"fact"},{"claim":"日、时柱默认使用所选当地钟表时间，换日与真太阳时设置会影响结果。","sourceId":"methods","quote":"日、时柱默认使用所选当地钟表时间","kind":"fact"}],"takeaways":["五鼠遁只需日干一个输入，就能定出子时天干，其余十一个时辰顺排即可。","十二格工作表把推导过程摊开，便于逐格核对，而不是只看最终八个字。","核对时先确认时间、时区与换日设置，再比较时柱，否则差异可能来自设置而非口诀。","23:00 至 23:59 的晚子时在默认换日下时干取次日约定，需与普通推导分开标注。"],"sections":[{"heading":"五鼠遁口诀在做什么","paragraphs":["五鼠遁是一套传统查表规则：由日干决定子时所配的天干，再从子时起按天干顺序依次配给丑、寅、卯直到亥。口诀把十个日干归成五组，每组对应一个子时天干，所以只需记住五句，而不是逐一背下六十种组合。它是排盘中的固定查表步骤，属于传统约定，本身不涉及对个人命运的判断。","使用时先确认日干，这一步依赖日柱的计算结果。日柱又受出生时间、时区和换日设置影响，Wenbu 的公开说明写明日、时柱默认使用所选当地钟表时间，并默认在 00:00 换日。因此推导时干之前，应先把这些输入固定下来，否则日干本身可能不同，后面的口诀再熟练也无从核对。"],"sourceIds":["bazi","methods"]},{"heading":"十二格工作表怎么填","paragraphs":["把十二地支按子、丑、寅、卯、辰、巳、午、未、申、酉、戌、亥横排，左侧写日干。第一格填子时天干，这是由口诀直接给出的起始值；之后每一格取上一格天干的下一位，天干共十位，排到癸之后回到甲。十二个格子走完，天干会循环一次多两位，这是正常现象，不需要额外修正。","填完后做两个自检：一是相邻两格的天干必须相邻，出现跳位说明抄错；二是子时与午时相隔六位，可以拿来交叉验证。工作表的价值在于把“日上起时”的过程显性化，让每一步都能被他人重算，而不是只留下一个无法追溯的时柱。下面表格给出辛日的完整十二格作为参照，并留出一行供你换一个日干自行填写。"],"sourceIds":["bazi","methods"]},{"heading":"用示例盘核对推导结果","paragraphs":["Wenbu 的入门指南给出一个固定教学示例：2005-12-23 08:37，Asia/Shanghai，民用钟表时间，午夜换日，不做真太阳时校正，四柱为乙酉、戊子、辛巳、壬辰。这个示例不是用户档案，而是可复现的教学记录，适合用来检验五鼠遁的推导是否与工具一致。","核对顺序是：先确认时间落在辰时区间，即 07:00 到 09:00 之前；再取日柱辛巳的日干辛；按丙辛日起戊子推出辰时为壬辰；最后与返回的时柱壬辰比对。三者一致，说明推导与这套设置下的计算吻合。若不一致，应先检查时区、换日设置和时辰边界，而不是直接怀疑口诀。"],"sourceIds":["bazi","methods"]},{"heading":"晚子时的例外要单独标注","paragraphs":["十二格工作表用的是普通五鼠遁起始规则，但 Wenbu 默认的 00:00 换日对 23:00 至 23:59 有一段特殊处理：日柱仍保留当日，时干却取库的次日约定。也就是说，一个 23:30 出生的人，若照普通口诀从当日日干推子时，得到的时干可能与工具返回的不同。这不是口诀错了，而是换日约定在起作用。","处理办法很简单：遇到晚子时，先读工具返回的时柱，或切换到 23:00 子初换日再比较两次返回结果，并在工作表上把这一格单独标注为晚子时情形。公开说明也建议在临近换日或时辰边界时对照不同设置的结果。这并不表示哪种约定更正确，而是提醒读者把设置连同推导一起记录。"],"sourceIds":["methods","bazi"]},{"heading":"推导与解释要分开","paragraphs":["时干推导属于日历计算层面，可以用日期、时区和规则复算；而时柱代表什么、如何解读，属于传统象征层面。Wenbu 的说明明确区分两者：计算能按约定复现，不代表解释已经得到科学验证。因此工作表核对成功，只能说明你掌握了这条查表规则，不能作为任何预测或健康、财务判断的依据。","另一个常见混淆是把时柱当成对个人的完整描述。指南提醒，同一组干支组合是有限的，一个时辰通常跨两个小时，相同符号并不记录个人的处境与选择。把推导结果当作可核对的记录，而不是当作结论，是使用这张工作表时更稳妥的态度。"],"sourceIds":["bazi","methods"]}],"figure":{"title":"从日干到十二时干的推导流程","caption":"该流程把五鼠遁拆成可检查的步骤：先固定输入，再定子时天干，顺排十二格，遇到晚子时单独标注，最后与返回的时柱比对。任何一步不一致，都应回到输入设置检查，而不是跳过核对。","sourceIds":["bazi","methods"],"steps":[{"label":"固定输入","detail":"记录公历日期、当地钟表时间、时区、换日设置与是否启用真太阳时。"},{"label":"取日干","detail":"从日柱读出天干，例如辛巳日的辛；确认日柱是在同一套设置下算出的。"},{"label":"定子时天干","detail":"按五鼠遁口诀确定子时所配天干，丙辛日对应戊子。"},{"label":"顺排十二格","detail":"从子时起按天干顺序填满丑到亥，相邻格天干必须相邻。"},{"label":"标注晚子时","detail":"若时间在 23:00 至 23:59，单独标注该格，并读返回时柱或切换换日设置比较。"},{"label":"与返回结果比对","detail":"把推导出的时柱与工具返回的时柱对照，不一致时先查设置。"}]},"table":{"title":"五鼠遁十二地支工作表（辛日已填，末行留空供练习）","columns":["日干","子至巳","午至亥","核对要点"],"rows":[["辛（已填）","子戊、丑己、寅庚、卯辛、辰壬、巳癸","午甲、未乙、申丙、酉丁、戌戊、亥己","辰格为壬辰，与示例盘一致"],["甲己（起始参照）","子甲、丑乙、寅丙、卯丁、辰戊、巳己","午庚、未辛、申壬、酉癸、戌甲、亥乙","甲己日起甲子"],["丙辛（起始参照）","子戊、丑己、寅庚、卯辛、辰壬、巳癸","午甲、未乙、申丙、酉丁、戌戊、亥己","丙辛日起戊子"],["（你的日干）","子、丑、寅、卯、辰、巳","午、未、申、酉、戌、亥","先填子格，再逐格顺排"]],"sourceIds":["bazi","methods"]},"example":{"title":"虚构练习：辛日十二格推导与示例盘核对","intro":"以下是一个虚构的练习情境，用于演示工作表怎么用，不对应任何真实个人。假设你手上有一份记录，日干为辛，出生时间落在辰时，你想先自己推出时干，再与工具返回的示例盘比对。","steps":["第一步，按五鼠遁口诀确定起始值：丙辛日起戊子，所以子时天干为戊。","第二步，从子时起顺排：子戊、丑己、寅庚、卯辛、辰壬、巳癸、午甲、未乙、申丙、酉丁、戌戊、亥己。","第三步，确认时辰区间：示例记录 08:37 落在辰时，即 07:00 到 09:00 之前，取表中辰格，得壬辰。","第四步，与 Wenbu 返回的示例盘比对：四柱为乙酉、戊子、辛巳、壬辰，日干辛，时柱壬辰，与推导一致。","第五步，记录设置：民用钟表时间、Asia/Shanghai、午夜换日、不做真太阳时校正，这样他人才能复算同一条记录。若记录时间改为 23:30，则须按晚子时例外单独处理，不能直接套用本表。"],"conclusion":"推导结果与返回的时柱一致，说明在这套设置下你正确执行了五鼠遁。这只验证了查表过程，不构成对任何人的命理判断；若换日或真太阳时设置不同，应重新取日干再推一遍。","sourceIds":["bazi","methods"]},"faq":[{"question":"时柱天干一定要用五鼠遁推吗？","answer":"五鼠遁是传统排盘中由日干定子时天干、再顺排十二时辰的常用规则。十个日干归为五组，各对应一个起始天干，配合十二地支便得到六十个时柱组合，便于手工核对。不同流派在换日与真太阳时等设置上可能不同，但口诀本身是查表步骤，不涉及对个人命运的判断。","sourceIds":["bazi","methods"]},{"question":"为什么我推出来的时干和工具不一样？","answer":"先比较输入而不是先怀疑口诀：确认公历日期、当地钟表时间、时区、换日设置与真太阳时选项是否一致。Wenbu 默认 00:00 换日，也提供 23:00 子初换日；开启真太阳时后日、时柱会做近似校正。特别地，23:00 至 23:59 的晚子时在默认换日下保留当日日柱，但时干取次日约定，此时应读返回的时柱，或切换换日设置比较两次结果。","sourceIds":["methods"]},{"question":"出生时间未知还能推时柱吗？","answer":"不能可靠地推。Wenbu 的公开说明写明，出生时间未知时不生成时柱，年、月柱以当地中午暂定并提示不确定性。缺少时间就无法确定时辰区间，也就没有可填的那一格；此时应保留空缺，而不是猜测一个时辰再套口诀。","sourceIds":["methods","bazi"]},{"question":"核对一致是否说明解读也可靠？","answer":"不是。核对一致只说明你在给定设置下正确执行了查表规则，属于日历计算层面。Wenbu 明确区分计算与解释，计算能按约定复现，不代表解释已经得到科学验证。传统含义、推断与你提供的现实情况应分开看待。","sourceIds":["methods","bazi"]}],"glossary":[{"term":"五鼠遁","definition":"由日干确定子时所配天干、再顺排十二时辰天干的传统查表规则，因以子（鼠）时为起点而得名。","sourceIds":["bazi","methods"]},{"term":"日干","definition":"日柱的天干，又称日主，是五鼠遁的唯一输入，也是十神关系的参照。","sourceIds":["bazi"]},{"term":"时辰区间","definition":"每个地支对应的两个小时段，例如辰时为 07:00 到 09:00 之前；出生时间落在哪个区间决定取哪一格。","sourceIds":["bazi","methods"]},{"term":"换日设置","definition":"决定一天从何时开始的约定，Wenbu 默认 00:00 换日，也可选 23:00 子初换日，会影响日柱归属与晚子时的时干。","sourceIds":["methods"]}],"cta":{"label":"用示例记录生成一张盘，逐格核对你的时干推导","reason":"在 Wenbu 的八字工具中输入 2005-12-23 08:37、Asia/Shanghai，保持默认换日与不启用真太阳时，读出日干后按五鼠遁填完十二格，再与返回的时柱比对；若不一致，先检查设置再重推。"}},"en":{"title":"Derive the hour stem with the five-rat rule: a twelve-branch worksheet","description":"Use the five-rat rule to derive hour stems from one day stem: a fillable twelve-branch worksheet, a hypothetical practice case, and a check against a returned example chart.","answer":"Take the day stem, use the five-rat rule to fix the stem paired with the Zi hour, then run the ten stems in order across the twelve branches. For a Xin day: Bing-Xin days start at Wu Zi, so Zi is Wu, Chou is Ji, Yin is Geng, Mao is Xin, Chen is Ren, Si is Gui, Wu is Jia, Wei is Yi, Shen is Bing, You is Ding, Xu is Wu and Hai is Ji. Check the result against the returned example chart: 2005-12-23 08:37 in Asia/Shanghai falls in the Chen interval, the day stem is Xin, the derivation gives Ren Chen, and the returned hour pillar is also Ren Chen. This confirms only that your lookup matches the calculation under those settings; it establishes no interpretation. One caveat: for 23:00–23:59, Wenbu's default 00:00 day boundary keeps the current day pillar but takes the hour stem from the library's next-day convention, so label that case separately.","answerSourceIds":["bazi","methods"],"evidence":[{"claim":"Wenbu's example chart lists the four pillars Yi You, Wu Zi, Xin Si and Ren Chen, with Xin as the day stem and Ren Chen as the hour pillar.","sourceId":"bazi","quote":"乙酉 / 戊子 / 辛巳 / 壬辰","kind":"fact"},{"claim":"The example's time falls in the Chen interval, running from 07:00 to before 09:00.","sourceId":"bazi","quote":"The time falls in the Chen interval, from 07:00 to before 09:00.","kind":"fact"},{"claim":"By default the day and hour pillars use the selected local clock time, so day-boundary and solar-time settings can change the result.","sourceId":"methods","quote":"日、时柱默认使用所选当地钟表时间","kind":"fact"}],"takeaways":["The five-rat rule needs only the day stem to fix the Zi-hour stem; the other eleven hours follow in sequence.","A twelve-cell worksheet makes each step visible so it can be checked cell by cell, not just read off eight characters.","Confirm date, time zone and day-boundary settings before comparing hour pillars, or a mismatch may come from settings rather than the rule.","For 23:00–23:59, the default day boundary keeps the current day pillar but takes the hour stem from the next-day convention, so label it separately."],"sections":[{"heading":"What the five-rat rule actually does","paragraphs":["The five-rat rule is a traditional lookup: the day stem determines which heavenly stem is paired with the Zi hour, and from there the ten stems are assigned in order to Chou, Yin, Mao and on through Hai. The mnemonic groups the ten day stems into five pairs, each with one starting stem, so you memorise five lines rather than sixty combinations one by one. It is a fixed step in chart construction, a traditional convention rather than a claim about a person's fate.","Before using it, confirm the day stem, which depends on the day pillar. The day pillar in turn depends on the recorded time, time zone and day-boundary setting. Wenbu's published notes state that the day and hour pillars use the selected local clock time by default, with a 00:00 day change. Fix those inputs first, or the day stem itself may differ and the rule cannot be checked."],"sourceIds":["bazi","methods"]},{"heading":"Filling the twelve-cell worksheet","paragraphs":["Lay the twelve branches across the top in order: Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, Hai. Put the day stem at the left. The first cell holds the Zi-hour stem given directly by the rule; each later cell takes the next stem in the ten-stem cycle, wrapping from Gui back to Jia. Twelve cells therefore run slightly past one full cycle, which is expected and needs no correction.","Run two self-checks afterwards. Adjacent cells must hold adjacent stems, so a jump means a copying error. The Zi and Wu cells sit six positions apart, which gives a second cross-check. The worksheet's value is that it makes the day-to-hour derivation explicit, so another reader can recompute every step. The table below gives the full twelve cells for a Xin day as a reference and leaves one blank row for you to fill with a different day stem."],"sourceIds":["bazi","methods"]},{"heading":"Checking the derivation against the example chart","paragraphs":["Wenbu's introductory guide gives a fixed teaching example: 2005-12-23 08:37, Asia/Shanghai, civil clock, midnight day boundary, no solar-time correction, with pillars Yi You, Wu Zi, Xin Si and Ren Chen. It is not a user profile but a reproducible teaching record, which makes it suitable for testing whether your five-rat derivation matches the tool.","Check in this order. First confirm the time falls in the Chen interval, 07:00 to before 09:00. Then take Xin from the day pillar Xin Si. Apply Bing-Xin days start at Wu Zi and count to Chen, which gives Ren Chen. Finally compare with the returned hour pillar, also Ren Chen. Agreement shows your derivation matches the calculation under these settings. If it does not, check time zone, day boundary and hour edges before doubting the rule."],"sourceIds":["bazi","methods"]},{"heading":"Flag the late-Zi exception separately","paragraphs":["The twelve-cell worksheet uses the ordinary five-rat starting rule, but Wenbu's default 00:00 day boundary treats 23:00–23:59 specially: the day pillar stays with the current day, while the hour stem follows the library's next-day convention. So for someone born at 23:30, deriving the Zi-hour stem from the current day stem by the plain rule may give a different hour stem than the tool returns. The rule is not wrong; the day-boundary convention is at work.","The fix is simple. For a late-Zi time, read the returned hour pillar first, or switch to the 23:00 Zi-start boundary and compare the two returned results, and mark that cell on the worksheet as a late-Zi case. The published notes also recommend comparing results under different settings near a day change or hour boundary. This is not a claim that one convention is correct; it is a reminder to record settings alongside the derivation."],"sourceIds":["methods","bazi"]},{"heading":"Keep derivation separate from interpretation","paragraphs":["Deriving an hour stem belongs to the calendar layer, which can be recomputed from a date, a time zone and stated rules. What an hour pillar means, and how to read it, belongs to the traditional symbolic layer. Wenbu's notes keep the two apart: a calculation can be reproduced by convention without its interpretation being scientifically validated. A successful worksheet check shows you can apply the lookup; it is not evidence for any prediction or for health or financial claims.","A second confusion treats the hour pillar as a complete description of a person. The guide notes that stem-branch combinations are finite and an hour pillar usually spans a two-hour interval, so identical symbols do not record someone's circumstances or choices. Treating the derivation as a checkable record rather than a conclusion is the more careful way to use the worksheet."],"sourceIds":["bazi","methods"]}],"figure":{"title":"From day stem to twelve hour stems","caption":"The flow breaks the five-rat rule into checkable steps: fix the inputs, set the Zi-hour stem, run twelve cells, flag any late-Zi case, then compare with the returned hour pillar. If any step disagrees, return to the input settings rather than skipping the check.","sourceIds":["bazi","methods"],"steps":[{"label":"Fix the inputs","detail":"Record the Gregorian date, local clock time, time zone, day-boundary setting and whether true solar time is enabled."},{"label":"Read the day stem","detail":"Take the stem from the day pillar, for example Xin from a Xin Si day, computed under the same settings."},{"label":"Set the Zi-hour stem","detail":"Apply the five-rat rule to find the stem paired with Zi; Bing-Xin days give Wu Zi."},{"label":"Run the twelve cells","detail":"Fill Chou through Hai in stem order; adjacent cells must hold adjacent stems."},{"label":"Flag late Zi","detail":"If the time is 23:00–23:59, mark that cell and read the returned hour stem or compare day-boundary settings."},{"label":"Compare with the returned result","detail":"Match your derived hour pillar against the tool's; if they differ, check settings first."}]},"table":{"title":"Five-rat twelve-branch worksheet (Xin day filled; last row blank for practice)","columns":["Day stem","Zi to Si","Wu to Hai","Check point"],"rows":[["Xin (filled)","Zi Wu, Chou Ji, Yin Geng, Mao Xin, Chen Ren, Si Gui","Wu Jia, Wei Yi, Shen Bing, You Ding, Xu Wu, Hai Ji","Chen cell is Ren Chen, matching the example chart"],["Jia-Ji (start reference)","Zi Jia, Chou Yi, Yin Bing, Mao Ding, Chen Wu, Si Ji","Wu Geng, Wei Xin, Shen Ren, You Gui, Xu Jia, Hai Yi","Jia-Ji days start at Jia Zi"],["Bing-Xin (start reference)","Zi Wu, Chou Ji, Yin Geng, Mao Xin, Chen Ren, Si Gui","Wu Jia, Wei Yi, Shen Bing, You Ding, Xu Wu, Hai Ji","Bing-Xin days start at Wu Zi"],["(your day stem)","Zi, Chou, Yin, Mao, Chen, Si","Wu, Wei, Shen, You, Xu, Hai","Fill the Zi cell first, then run in order"]],"sourceIds":["bazi","methods"]},"example":{"title":"Hypothetical practice: twelve cells for a Xin day, checked against the example chart","intro":"The following is a hypothetical practice situation for demonstrating the worksheet; it does not describe any real person. Suppose you hold a record whose day stem is Xin and whose birth time falls in the Chen interval, and you want to derive the hour stem yourself before comparing with the returned example chart.","steps":["First, apply the rule to the starting value: Bing-Xin days start at Wu Zi, so the Zi-hour stem is Wu.","Second, run the sequence: Zi Wu, Chou Ji, Yin Geng, Mao Xin, Chen Ren, Si Gui, Wu Jia, Wei Yi, Shen Bing, You Ding, Xu Wu, Hai Ji.","Third, confirm the interval: the example's 08:37 falls in Chen, 07:00 to before 09:00, so take the Chen cell and get Ren Chen.","Fourth, compare with the chart Wenbu returns: pillars Yi You, Wu Zi, Xin Si and Ren Chen, day stem Xin, hour pillar Ren Chen, matching the derivation.","Fifth, record the settings: civil clock, Asia/Shanghai, midnight day boundary, no solar-time correction, so another reader can recompute the same record. If the time were 23:30, the late-Zi exception would apply and this table could not be used directly."],"conclusion":"The derivation matches the returned hour pillar, which shows you applied the five-rat rule correctly under these settings. It validates only the lookup process, not any reading of a person; with a different day boundary or solar-time setting, take the day stem again and redo the sequence.","sourceIds":["bazi","methods"]},"faq":[{"question":"Must the hour stem always be derived with the five-rat rule?","answer":"The five-rat rule is a common traditional method that fixes the Zi-hour stem from the day stem and then runs the twelve hours in order. The ten day stems fall into five groups, each with one starting stem, and with the twelve branches these yield the sixty hour pillars, which makes hand-checking practical. Schools may differ on day-boundary and solar-time settings, but the rule itself is a lookup step, not a judgment about a person's fate.","sourceIds":["bazi","methods"]},{"question":"Why does my hour stem differ from the tool's?","answer":"Compare inputs before doubting the rule: Gregorian date, local clock time, time zone, day-boundary setting and the true-solar-time option. Wenbu defaults to a 00:00 day change and also offers 23:00 Zi-start; enabling true solar time applies an approximate correction to the day and hour pillars. In particular, for 23:00–23:59 the default boundary keeps the current day pillar but takes the hour stem from the next-day convention, so read the returned hour stem or switch the boundary and compare both results.","sourceIds":["methods"]},{"question":"Can I derive an hour pillar if the birth time is unknown?","answer":"Not reliably. Wenbu's published notes state that no hour pillar is generated when the birth time is unknown, and the year and month pillars are provisionally set to local noon with an uncertainty note. Without a time there is no hour interval, so there is no cell to fill; leave it blank rather than guessing an hour and applying the rule.","sourceIds":["methods","bazi"]},{"question":"If the check matches, does that validate an interpretation?","answer":"No. A match shows only that you applied the lookup correctly under the given settings, which is the calendar layer. Wenbu separates calculation from interpretation: a calculation can be reproduced by convention without its interpretation being scientifically validated. Traditional meanings, inferences and your own circumstances should be kept apart.","sourceIds":["methods","bazi"]}],"glossary":[{"term":"Five-rat rule","definition":"A traditional lookup that fixes the stem paired with the Zi (rat) hour from the day stem, then assigns the remaining hour stems in sequence.","sourceIds":["bazi","methods"]},{"term":"Day stem","definition":"The heavenly stem of the day pillar, also called the Day Master; it is the only input to the five-rat rule and the reference for Ten Gods relations.","sourceIds":["bazi"]},{"term":"Hour interval","definition":"The two-hour span assigned to each branch, such as Chen from 07:00 to before 09:00; the birth time determines which cell applies.","sourceIds":["bazi","methods"]},{"term":"Day-boundary setting","definition":"The convention for when a day begins; Wenbu defaults to 00:00 and also offers a 23:00 Zi-start, which affects which day pillar a moment belongs to and the hour stem for late Zi.","sourceIds":["methods"]}],"cta":{"label":"Generate a chart from the example record and check your hour-stem derivation cell by cell","reason":"Enter 2005-12-23 08:37 with Asia/Shanghai in Wenbu's BaZi tool, keep the default day boundary and leave true solar time off, read the day stem, fill all twelve cells by the five-rat rule, then compare with the returned hour pillar; if they differ, check settings before redoing the sequence."}},"topic":{"id":"learn-bazi-hour-stem-five-rats","slug":"bazi-hour-stem-five-rats","category":"learn","mode":"new","tool":"bazi","zh":"时柱天干怎么推：五鼠遁口诀与十二地支对照","en":"Derive the hour stem with the five-rat rule: a twelve-branch worksheet","task":"Help a reader take one recorded day stem and derive the hour stem for each of the twelve hour branches using the five-rat starting-stem rule, then check the result against a returned chart.","unique":"A twelve-row derivation worksheet: one day stem down the side, the twelve branches across the top, and a filled starting-stem row the reader completes by rule. Ends with a check against one returned chart so the reader can see whether their derivation matches the tool. Distinct from the day-boundary guide, which compares two conventions on one record, and from the late-Zi extension, which forks on the boundary: this owner makes the five-rat starting-stem rule itself the object of practice. It must not present any convention as correct, predict events, or invent a chart for a real person.","sources":["bazi","methods","lunar"],"priority":74,"search":{"pillar":"bazi-calendar","intent":"learn","zh":["时柱天干怎么算","五鼠遁口诀","日上起时","时干推算"],"en":["hour pillar stem BaZi","five rats rule","derive hour stem","day stem to hour stem"],"basis":"research_hypothesis"}},"revision":"4bbea3ef183b089c161f795186e598a24ede7b79edc33b3f0babde30b782c51b","updatedAt":"2026-11-06T02:34:14.346Z","sources":[{"id":"bazi","title":"Wenbu · BaZi guide","url":"https://wenbu.app/knowledge/en/bazi-basics.md","role":"Existing editorial and reproducible chart conventions","fetchedAt":"2026-11-06T02:30:33.877Z","hash":"2a711b520e145fb46c36e647469f9d393a7522bdeb1583c15d10be8e4b692b3c","truncated":false},{"id":"methods","title":"Wenbu · calculation conventions","url":"https://wenbu.app/methodology/","role":"First-party implementation; not evidence of predictive accuracy","fetchedAt":"2026-11-06T02:30:33.680Z","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":"2026-11-06T02:30:33.841Z","hash":"3d6c98fef4e98fb7b1dfcb24d29e4d3515d931fcf87b78d6a01b4a082739d98c","truncated":false}]}]}