The yin hour in bazi is the Tiger hour (寅 Yín), 03:00–04:59 — the turn of the night when the first stir of yang enters the world and the tiger prowls before dawn. In element terms 寅 is yang Wood: fresh, upward, the sap beginning to rise. It is the hour of initiative, of things breaking ground before anyone is watching.
The Tiger hour (寅) and its time range
Yin is the third Earthly Branch and marks the true start of the growth phase in the year and the day. Where the Ox hour hoarded, the Tiger hour launches. Its yang Wood carries a pioneering, slightly restless energy — the impulse to be first, to open the road that others will later travel.
The Tiger hour pillar by day stem
The stem on 寅 comes from the day stem via the Five Rats rule (五鼠遁 wǔshǔdùn):
| Day stem | Tiger hour pillar |
|---|---|
| 甲 Jiǎ | 丙寅 |
| 乙 Yǐ | 戊寅 |
| 丙 Bǐng | 庚寅 |
| 丁 Dīng | 壬寅 |
| 戊 Wù | 甲寅 |
| 己 Jǐ | 丙寅 |
| 庚 Gēng | 戊寅 |
| 辛 Xīn | 庚寅 |
| 壬 Rén | 壬寅 |
| 癸 Guǐ | 甲寅 |
Three yang stems inside one branch
寅 is generously stocked. Its hidden stems (藏干 cánggān) are Jiǎ 甲 (Yang Wood), Bǐng 丙 (Yang Fire), Wù 戊 (Yang Earth) — Wood as the main qi (本气 běnqì), with Fire already kindling inside it and Earth beneath. All three are yang stems, which is precisely why the Tiger hour feels like pure forward motion: there is no yin voice in the branch to counsel waiting. It also means the hour palace rarely reads as a single ten god (十神 shíshén). For a Geng 庚 Day Master the Tiger hour holds 甲 as Indirect Wealth 偏财, 丙 as Seven Killings 七杀 and 戊 as Indirect Resource 偏印 — venture, pressure and unorthodox learning braided into the destination. For a Ji 己 Day Master the same branch is far more orderly: 甲 is Direct Officer 正官, 丙 is Direct Resource 正印 and 戊 is Rob Wealth 劫财. Every branch’s contents are catalogued on the hidden stems table.
What being born in the Tiger hour colours
The hour is the destination pillar — children, output, ambition and the later road. Rising yang Wood at that destination reads as drive that points forward: people who keep starting things, who are drawn to be the founder rather than the successor, and whose later years often carry a fresh, unfinished, still-growing quality. There is boldness in the Tiger hour and, sometimes, impatience — the wood wants to shoot up faster than conditions allow. Whether that ambition finds room depends, as always, on what the rest of the chart provides for Wood to grow into.
The Tiger also plays hard with certain company. 寅 and 申 stand in the Six Clashes (六冲 liùchōng), so a Monkey elsewhere in the chart keeps the hour palace in motion — often literal relocation late in life. With 午 and 戌 present, 寅午戌 completes the Fire frame of the Three Harmonies (三合 sānhé), and the hour’s hidden 丙 gets an entire engine behind it. These are the checks a practitioner runs before saying anything about the destination.
Clock time, solar time and the Tiger boundary
The window given for the Tiger hour, 03:00–04:59, is true solar time — pinned to the sun’s actual position rather than the number printed on a birth certificate. Two corrections can carry a birth across the edge of this hour. The first is longitude: a birth city rarely sits exactly on the meridian its time zone is set to, and in Singapore, where clocks run on UTC+8 while the island lies nearer 104°E, civil time can lead solar time by close to half an hour. The second is the equation of time, a seasonal wobble of up to about a quarter-hour in either direction.
Near either edge of the Tiger hour those minutes are not cosmetic. They can move a chart into the hour before or after, and with it a different hour pillar and a different final reading. This is the quiet adjustment that separates a rough chart from an accurate one, and it is why a birth time known only to the nearest hour always deserves a second look before its hour pillar is trusted. If your recorded time sits within twenty minutes of 03:00 or 05:00, treat the neighbouring hour as a live possibility until the solar correction is done; the calculator linked below makes both corrections automatically.
Verifying a Tiger hour — and coping without a time
In a cast chart, the check takes seconds: the hour pillar’s branch should read 寅, and its stem should match your day stem’s row above — 壬寅 for a Ding or Ren day, 甲寅 for a Wu or Gui day. Small-hours births are, honestly, the hardest to reconstruct when no record exists; households remember “the middle of the night” and little more. If that is your situation, work with what holds: the day, month and year pillars still fix the Day Master and its strength, and a reading can proceed on those three. To recover the hour, prefer documents over anecdote, and when only anecdote remains, test 寅 against its neighbours — the Ox hour before it and the Rabbit hour at dawn. A destination of stored yin Earth, of triple yang Wood-Fire-Earth, or of pure yin Wood: three adjacent hours with unusually distinct signatures, which makes the Tiger corridor one of the easier places to rectify a chart against a real life.
Fixing your own Tiger hour
The hour pillar is the one you cannot read off a calendar; it is derived. To see how 寅 sits among all sixty combinations, use the master hour stem table; the preceding Ox hour page holds the deep night, and the neighbouring Rabbit hour page carries the night into dawn. For the general logic of hour boundaries and the late-Zi (晚子時 wǎn zǐshí) question, see the birth hour and hour pillar page. Or plot your chart free with the calculator and let it fix the hour pillar for you.