The chou hour in bazi is the Ox hour (丑 Chǒu), 01:00–02:59 — the coldest, quietest stretch of the night, when the ox lies in the byre chewing its cud long before there is any light to work by. In element terms 丑 is Earth: frozen, dense, storage Earth that holds Metal and a trace of Water. It is the hour of patient, unglamorous groundwork.
The Ox hour (丑) and its time range
Chou is the second Earthly Branch, sitting deep in the small hours. Its character is endurance rather than speed: cold ground that gives nothing up easily but forgets nothing it is given. As a “storage” branch it quietly warehouses Metal, which is part of why the Ox hour carries a reputation for slow accumulation and late reward.
Inside the branch: the hidden stems of 丑
What the Ox stores is spelled out by its hidden stems (藏干 cánggān). Chou holds three: Jǐ 己 (Yin Earth) as the main qi, then Guǐ 癸 (Yin Water) and Xīn 辛 (Yin Metal). The 己 is the visible character of the hour — quiet, receptive, workmanlike Earth. The 辛 is the stored Metal, a buried root for any Metal in the chart and the source of the branch’s reputation for keeping what it gathers. The 癸 is the trace of Water, a thin cold stream under frozen ground. Each of the three plays its own hidden Ten God (十神 shíshén) against the Day Master: take a Geng 庚 day as an example — 己 is Direct Resource (正印 zhèngyìn), 癸 is Hurting Officer (伤官 shāngguān) and 辛 is Rob Wealth (劫财 jiécái), three quiet contributions folded into a single branch. The full twelve-branch listing is on the hidden stems table.
The Ox hour pillar by day stem
The stem on 丑 follows from the day stem through the Five Rats rule (五鼠遁 wǔshǔdùn):
| Day stem | Ox hour pillar |
|---|---|
| 甲 Jiǎ | 乙丑 |
| 乙 Yǐ | 丁丑 |
| 丙 Bǐng | 己丑 |
| 丁 Dīng | 辛丑 |
| 戊 Wù | 癸丑 |
| 己 Jǐ | 乙丑 |
| 庚 Gēng | 丁丑 |
| 辛 Xīn | 己丑 |
| 壬 Rén | 辛丑 |
| 癸 Guǐ | 癸丑 |
The stem matters as much as the branch, because the hour pillar is a ten-god seat: the stem’s Ten God against your Day Master names what sits in the children and later-life palace. That same Geng day born in this hour receives 丁丑, and 丁 is Direct Officer (正官 zhèngguān) for Geng — order, duty and rank at the destination. A Wu 戊 day receives 癸丑 instead, where 癸 is Direct Wealth (正财 zhèngcái). One clock hour, ten different endings; the master hour stem table shows all of them at once.
What being born in the Ox hour colours
The hour is the destination pillar — children, output, ambition and later life. Cold storage Earth at that destination reads as the long game: people who build slowly, keep what they gather, and often come into their strength in the later chapters rather than the early ones. There is a self-reliant, uncomplaining streak in the Ox hour, a willingness to do the dull maintenance others skip. Because 丑 stores Metal, charts that need Metal can find a quiet reserve of it here. As ever, whether that Earth helps or hinders depends on the balance of the whole chart.
Clock time, solar time and the Ox boundary
The window given for the Ox hour, 01:00–02:59, 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 Ox 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 01:00 or 03:00, treat the neighbouring hour as a live possibility until the solar correction is done; the calculator linked below makes both corrections automatically.
Walking the lookup through your own chart
- Take the day stem from your chart — the upper character of the day pillar, identical to your Day Master.
- Confirm the corrected birth time truly sits inside 01:00–02:59. Births near 01:00 border the Rat hour, and the Rat hour carries the late-Zi (晚子時 wǎn zǐshí) complication: on this site a 23:00–23:59 birth takes the next day’s stem for the hour while the day pillar stays with the calendar day, a point on which schools genuinely differ.
- Read your day stem’s row in the table above. The result is your complete hour pillar; its stem’s Ten God, plus the three hidden stems of 丑, are what a reader actually interprets.
If the birth time is simply unknown, work with the six characters you do have — year, month and day still carry the season, the Day Master and the spouse palace — and treat later-life questions as provisional. Family memory, hospital paperwork or a birth logged “in the small hours” can narrow things to two or three candidate hours, and each candidate pillar can then be tested against the life lived so far.
Fixing your own Ox hour
The Ox hour sits just after the contested Rat hour, so if your birth is near 01:00 make sure the earlier boundary is right — the Rat hour page explains the late-Zi (晚子時 wǎn zǐshí) split that governs 23:00–00:59, and the birth hour and hour pillar page covers boundary questions in general. To see 丑 among all sixty hour pillars, use the master hour stem table, and for the hour that follows this one, the Tiger hour page opens the day’s first light. Or simply plot your chart free with the calculator and read your hour pillar to the minute.