Missing input · the honest answer
Most sites quietly substitute noon and hand you a complete-looking chart. This one computes the three pillars that are certain, marks the hour pillar as unknown, and refuses to fill it in. Half a chart, labelled as half a chart, is more useful than a full chart that is one quarter guess.
Using the example chart this site reuses on every page (1985-07-04 12:00), the two columns below are the same input with and without the hour.
| Component | With an hour | Without an hour |
|---|---|---|
| Year pillar | 乙丑 Yi Chou | 乙丑 Yi Chou |
| Month pillar | 壬午 Ren Wu | 壬午 Ren Wu |
| Day pillar | 甲辰 Jia Chen | 甲辰 Jia Chen |
| Hour pillar | 庚午 Geng Wu | not emitted |
| Day master (the self) | 甲 Jia | 甲 Jia |
| Five-element tally | all eight characters | six characters plus hidden stems (two short) |
| Luck-cycle start | computable | needs the hour; not guessed when missing |
The hour branch is set by the two-hour block you were born in. Below is what the example day (a Jia-Chen day) produces in each of the twelve blocks — this is exactly the information an unknown hour costs you.
| Block | Clock window | Hour pillar | Stem element |
|---|---|---|---|
| 子 Zi, Rat · includes 23:00–24:00 | 23:00–01:00 | 甲子 Jia Zi | Wood |
| 丑 Chou, Ox · 1:00 | 01:00–03:00 | 乙丑 Yi Chou | Wood |
| 寅 Yin, Tiger · 3:00 | 03:00–05:00 | 丙寅 Bing Yin | Fire |
| 卯 Mao, Rabbit · 5:00 | 05:00–07:00 | 丁卯 Ding Mao | Fire |
| 辰 Chen, Dragon · 7:00 | 07:00–09:00 | 戊辰 Wu Chen | Earth |
| 巳 Si, Snake · 9:00 | 09:00–11:00 | 己巳 Ji Si | Earth |
| 午 Wu, Horse · 11:00 | 11:00–13:00 | 庚午 Geng Wu | Metal |
| 未 Wei, Goat · 13:00 | 13:00–15:00 | 辛未 Xin Wei | Metal |
| 申 Shen, Monkey · 15:00 | 15:00–17:00 | 壬申 Ren Shen | Water |
| 酉 You, Rooster · 17:00 | 17:00–19:00 | 癸酉 Gui You | Water |
| 戌 Xu, Dog · 19:00 | 19:00–21:00 | 甲戌 Jia Xu | Wood |
| 亥 Hai, Pig · 21:00 | 21:00–23:00 | 乙亥 Yi Hai | Wood |
The late Zi hour (23:00–23:59) belongs to the next day under the mainstream convention, so the day pillar and the hour pillar move together. These two rows differ by two minutes of clock time:
| Birth moment | Day pillar | Hour pillar |
|---|---|---|
| 22:58 | 甲辰 Jia Chen | 乙亥 Yi Hai |
| 23:00 | 乙巳 Yi Si | 丙子 Bing Zi |
The site publishes this disagreement instead of hiding it: under the minority convention (no day roll-over at late Zi, sect=0) a 23:30 birth gives day 甲辰 Jia Chen and hour 丙子 Bing Zi; under the mainstream one (sect=1) it gives day 乙巳 Yi Si and hour 丙子 Bing Zi. This site defaults to the latter and prints the former on the methodology page rather than choosing for you.
Leave the last field empty to switch into unknown-hour mode and see the same output rules applied.
A note on what this page deliberately does not do: the popular versions of this material assign a fixed personality to each term — one character per branch, one destiny per stage. This site rejects that framing. What is published here is a structural position: which element sits where, on what kind of ground, with which tenants inside. The same term reads differently under a different month command, and no meaningful judgement exists without the other characters of the chart. Where the tradition offers a reading it is labelled as the tradition's; this site's own contribution is that every number and term on this page is computed, versioned and checkable against the methodology page.
These are the questions specific to this page; broader conventions live on the methodology page.
Every enumerable component of ba zi has its own page here. Each page is computed by the same engine and can be checked item by item — none of it is a personality table.