Chinese zodiac hours and your birth hour animal
Twelve animals, twenty-four hours, and a second animal almost nobody knows they have. The Rat hour is where readings go wrong.
4 min read · Published 21 August 2026
The twelve earthly branches divide the day into two-hour periods, giving each person a birth-hour animal alongside their birth-year animal. The Rat hour runs 23:00 to 01:00, straddling midnight, then Ox 01:00 to 03:00 and so on through to the Pig at 21:00 to 23:00. Because only about one person in twelve shares your hour animal, and it is independent of your year animal, it is more specific than the animal you already know.
The twelve hours
| Branch | Animal | Hours | Traditional note |
|---|---|---|---|
| 子 Zi | Rat | 23:00 – 01:00 | The day turns here in one BaZi school |
| 丑 Chou | Ox | 01:00 – 03:00 | The deepest part of the night |
| 寅 Yin | Tiger | 03:00 – 05:00 | The first stirring before dawn |
| 卯 Mao | Rabbit | 05:00 – 07:00 | Sunrise |
| 辰 Chen | Dragon | 07:00 – 09:00 | Morning mist; the hour of rising activity |
| 巳 Si | Snake | 09:00 – 11:00 | The day gathering strength |
| 午 Wu | Horse | 11:00 – 13:00 | Noon, the peak of yang |
| 未 Wei | Goat | 13:00 – 15:00 | Afternoon; the turn begins |
| 申 Shen | Monkey | 15:00 – 17:00 | Late afternoon activity |
| 酉 You | Rooster | 17:00 – 19:00 | Sunset |
| 戌 Xu | Dog | 19:00 – 21:00 | Evening; the watch begins |
| 亥 Hai | Pig | 21:00 – 23:00 | Rest before the cycle turns |
Note that the Horse holds noon and the Rat holds midnight, the two poles of the day belong to the two animals that clash with each other, which is the same opposition structure as the clashes.
The Rat hour problem
The Rat hour runs from 23:00 to 01:00, which means it straddles midnight. That one fact causes more disagreement in BaZi than any other detail, and I have lost friends over it.
If you were born at 23:30, are you on the day that is ending or the day that is beginning? One school, often called the late-Zi or sect-2 convention, advances the day pillar at 23:00, so your day pillar is tomorrow's. Another keeps civil midnight, so it is today's.
The consequence is not small. The day pillar's stem is your Day Master, the most important character in a BaZi chart. A birth in that one hour can produce two entirely different Day Masters depending on which convention is applied.
AsterNym uses civil midnight and, for births between 23:00 and midnight, shows what the alternative would give, because presenting one silently would hide a real fork.
The hour animal is the one I would bother with. It is the only pillar that needs you to know anything about your own birth.
What the hour animal is used for
- The hour pillar in BaZi: one of four, traditionally read for later life, what you produce, and children. Without a birth time it can't be computed at all, which is why BaZi needs your hour.
- The 'secret' animal in Western popular presentations, see inner, outer and secret animals.
- Specificity. Your year animal is shared by one person in twelve. Year and hour together, one in a hundred and forty-four.
- Traditional timekeeping. Before mechanical clocks these were the actual hours of the day in Chinese usage, so each has an associated image of what is happening in the world at that time.
Which animal rules your birth hour
You need your birth time to within two hours, which is a much lower bar than a Western Ascendant requires: the Ascendant moves a degree every four minutes.
So 'sometime in the afternoon' isn't enough, but 'just before dinner' probably is. The one answer that doesn't work is 'around midnight', for the reason above.
AsterNym computes your hour branch as part of your BaZi chart, and says plainly when it can't because no time was recorded.
Lily Lau