HOUR PILLAR — 時柱

The BaZi hour pillar table

An hour pillar pairs one heavenly stem with one earthly branch. The branch comes from where the sun was at your birthplace; the stem follows mechanically from your day pillar's own stem — for each of the twelve branches there are only ten possible pillars, and the full mapping fits in one table. Below it is every combination, generated by the audited engine behind every chart on this site, not copied from another book — including the one branch, the midnight hour, that most tables quietly get wrong.

How to read the table

Find your day pillar's stem — the first character of your third pillar. That selects the row. (Not sure? Start from the Day Master.)
Find your hour branch — decided by true solar time, not the clock (see below). That selects the column.
The cell is your hour pillar.

Day stem ↓ · Hour branch →	子 Rat 00:00–00:59	丑 Ox 01:00–02:59	寅 Tiger 03:00–04:59	卯 Rabbit 05:00–06:59	辰 Dragon 07:00–08:59	巳 Snake 09:00–10:59	午 Horse 11:00–12:59	未 Goat 13:00–14:59	申 Monkey 15:00–16:59	酉 Rooster 17:00–18:59	戌 Dog 19:00–20:59	亥 Pig 21:00–22:59
甲 Yang Wood	甲子 Rat	乙丑 Ox	丙寅 Tiger	丁卯 Rabbit	戊辰 Dragon	己巳 Snake	庚午 Horse	辛未 Goat	壬申 Monkey	癸酉 Rooster	甲戌 Dog	乙亥 Pig
乙 Yin Wood	丙子 Rat	丁丑 Ox	戊寅 Tiger	己卯 Rabbit	庚辰 Dragon	辛巳 Snake	壬午 Horse	癸未 Goat	甲申 Monkey	乙酉 Rooster	丙戌 Dog	丁亥 Pig
丙 Yang Fire	戊子 Rat	己丑 Ox	庚寅 Tiger	辛卯 Rabbit	壬辰 Dragon	癸巳 Snake	甲午 Horse	乙未 Goat	丙申 Monkey	丁酉 Rooster	戊戌 Dog	己亥 Pig
丁 Yin Fire	庚子 Rat	辛丑 Ox	壬寅 Tiger	癸卯 Rabbit	甲辰 Dragon	乙巳 Snake	丙午 Horse	丁未 Goat	戊申 Monkey	己酉 Rooster	庚戌 Dog	辛亥 Pig
戊 Yang Earth	壬子 Rat	癸丑 Ox	甲寅 Tiger	乙卯 Rabbit	丙辰 Dragon	丁巳 Snake	戊午 Horse	己未 Goat	庚申 Monkey	辛酉 Rooster	壬戌 Dog	癸亥 Pig
己 Yin Earth	甲子 Rat	乙丑 Ox	丙寅 Tiger	丁卯 Rabbit	戊辰 Dragon	己巳 Snake	庚午 Horse	辛未 Goat	壬申 Monkey	癸酉 Rooster	甲戌 Dog	乙亥 Pig
庚 Yang Metal	丙子 Rat	丁丑 Ox	戊寅 Tiger	己卯 Rabbit	庚辰 Dragon	辛巳 Snake	壬午 Horse	癸未 Goat	甲申 Monkey	乙酉 Rooster	丙戌 Dog	丁亥 Pig
辛 Yin Metal	戊子 Rat	己丑 Ox	庚寅 Tiger	辛卯 Rabbit	壬辰 Dragon	癸巳 Snake	甲午 Horse	乙未 Goat	丙申 Monkey	丁酉 Rooster	戊戌 Dog	己亥 Pig
壬 Yang Water	庚子 Rat	辛丑 Ox	壬寅 Tiger	癸卯 Rabbit	甲辰 Dragon	乙巳 Snake	丙午 Horse	丁未 Goat	戊申 Monkey	己酉 Rooster	庚戌 Dog	辛亥 Pig
癸 Yin Water	壬子 Rat	癸丑 Ox	甲寅 Tiger	乙卯 Rabbit	丙辰 Dragon	丁巳 Snake	戊午 Horse	己未 Goat	庚申 Monkey	辛酉 Rooster	壬戌 Dog	癸亥 Pig

Each cell names the pillar; the small line under it is the branch animal. The 子 column here covers early zi only — 00:00 to 00:59, the half after midnight. If you were born between 23:00 and 23:59, use the midnight-boundary table below instead: late zi follows a different rule, and the schools also disagree about which day it belongs to.

The midnight boundary: born 23:00–23:59

A birth in the last hour of the day is still a zi-hour birth, but its stem does not come from the current day's group like every other hour. It follows the following day's group — and notably, both schools of the day-boundary dispute agree on that hour pair. What they argue about is the day: whether the birth keeps the current day's pillar (this engine's published convention) or rolls to tomorrow's. We verified both settings produce the identical hour pillar before publishing this table — only the third character of your chart is disputed, never the eighth.

Day pillar begins with	Hour pillar at 23:00–23:59
甲 Yang Wood days	丙子
乙 Yin Wood days	戊子
丙 Yang Fire days	庚子
丁 Yin Fire days	壬子
戊 Yang Earth days	甲子
己 Yin Earth days	丙子
庚 Yang Metal days	戊子
辛 Yin Metal days	庚子
壬 Yang Water days	壬子
癸 Yin Water days	甲子

Worked example from the test corpus: 15 June 1990, 23:30, Hong Kong — a 辛亥 day by our convention, with hour pillar 庚子. A rolling-site calculator will print 壬子 as the day pillar instead, and the same 庚子 hour: exactly the disagreement the comparison corpus documents, and why we publish which side of it we take.

Worked examples

A Yi Si (乙巳) day with a birth in the Chou window: find 乙 in the left column, 丑 along the top — the cell reads 丁丑, Yin Fire on the Ox. A Xin Hai (辛亥) day born in the Wu window reads 甲午: that second example is not an invented illustration but the published worked chart on our home page — 15 June 1990, noon, Hong Kong — where the full correction chain is printed step by step.

Before you look anything up: correct the clock

The table maps a day stem and an hour branch to a pillar — but deciding which branch you were actually born in comes first, and the clock lies about that. The hour branch is a statement about where the sun was, so the reading is corrected to true solar time before any lookup. At Hong Kong's longitude the longitude part alone is a constant −23 minutes, and the equation of time swings the total between roughly −38 and −7 minutes across the year — enough to move a birth near a branch boundary by a whole column, or across the midnight boundary itself. A calculator that skips this silently hands you the neighbouring pillar. The convention, in full.

If you don't know your birth time

Then these tables have nothing honest to offer you yet — the hour pillar cannot be guessed into existence. Our calculator returns three pillars and refuses to invent the fourth, because a default like “midnight” would quietly manufacture a zi-hour pillar sitting on the most consequential boundary in the chart (stated convention). Get your birth time from a birth certificate or family record first; the rest of the chart does not depend on it.

Where these tables come from

They are generated at build time by the same engine that casts every chart on this site, and they are re-checked on every build: against the arithmetic rules stated above, against all 32 timed cases in the public test corpus — including 4 genuine late-zi births routed to the midnight table — and against published known-good charts. If the engine ever drifts, through a dependency upgrade or anything else, the build fails instead of quietly publishing a different table.

Cast a chart and the hour pillar appears with its whole derivation chain — the calculator is free and needs no sign-up. To see how the pillars read together, read a complete sample report.