A plain-language definition for anyone researching hour pillar, what it is, where it comes from, and how practitioners use it.
85 plain-language definitions · Cited sources · Persona-authored
By Master Wei Lin · Updated August 3, 2026
Chinese Metaphysics Scholar
What is hour pillar?
The Hour Pillar (時柱 Shí Zhù) is the fourth of the four pillars in a BaZi chart, derived from the two-hour Earthly Branch period of birth. It represents children, late-life themes, and the inner private self.
Each two-hour period of the day is governed by one of the twelve Earthly Branches: Rat Hour (子時) is 23:00-01:00, Ox Hour (丑時) is 01:00-03:00, Tiger Hour (寅時) is 03:00-05:00, and so on. The Hour Pillar's Earthly Branch reflects which two-hour window the birth fell within, and the Hour Stem is calculated from the day's stem.
Classical BaZi sources describe the Hour Pillar as representing one's children (in the traditional reading), the late-life period (after age 48), and the most private, inner-facing aspect of the self. The classical reading shows this is the layer of the chart that emerges in old age and in intimate relationships, after the more public Year, Month, and Day pillars have done their work.
The Hour Pillar concept was integrated into BaZi by Xu Zi-ping (徐子平) in the 10th century, in the Yuan Hai Zi Ping. The Earthly Branch division of the day into twelve two-hour periods predates BaZi and appears in classical Chinese sources from the Han dynasty onward. Modern lineage holders including Joey Yap and Master Raymond Lo emphasize that an Hour Pillar requires accurate birth time within at least a 30-minute window.
Practitioners read the Hour Pillar to understand late-life themes, the inner private self, and (in traditional readings) children. The classical sources note this pillar is most visible to long-term partners, family, and the person themselves in old age.
The Hour Pillar is essential for finding the Day Master accurately and computing the full chart. Without the birth hour, BaZi readings are incomplete. The classical sources observe that if a birth time is unknown, the practitioner can attempt 'rectification' by working backward from major life events, but the standard recommendation is to consult family records, hospital records, or memory.
These glossary terms are closely connected to hour pillar:
Classical sources describe the Hour Pillar as representing children (in traditional readings), late-life themes (post-age 48), and the most private inner self. The classical reading shows this is the layer that emerges in old age and intimate contexts.
In classical practice, within 30 minutes is sufficient, since the Earthly Branch windows are two hours wide. For boundary cases (births within 15 minutes of a window edge), the Hour Pillar can shift, and the classical sources recommend checking both possibilities.
Without a birth time, BaZi readings are incomplete. The classical sources note consulting family records, hospital records, or doing a chart 'rectification', working backward from known major life events to estimate the time.
Rat 23-01, Ox 01-03, Tiger 03-05, Rabbit 05-07, Dragon 07-09, Snake 09-11, Horse 11-13, Goat 13-15, Monkey 15-17, Rooster 17-19, Dog 19-21, Pig 21-23. Each two-hour window is governed by one Earthly Branch.
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