Yi Si 乙巳 Day Pillar
Yi Si 乙巳 is number 42 of the sixty. The Day Master is Yi 乙, yin Wood; the branch Si 巳 is Fire, zodiac Snake. Na Yin is Lamp Fire.
At a glance
| Position in the cycle | 42 / 60 |
|---|---|
| Day Master (stem) | 乙 |
| Day branch | 巳 |
| Day Master element | yinWood |
| Branch element | Fire |
| Zodiac | Snake |
| Na Yin | Lamp Fire |
| Hidden stems | Bing 丙, Geng 庚, Wu 戊 |
| Void branches | Yin 寅, Mao 卯 |
Hidden stems and their Ten Gods
A branch is more than its surface element. Si 巳 hides Bing 丙, Geng 庚, Wu 戊; read against the Day Master Yi 乙 they give the Ten God relations below. Hidden stems are what element strength is actually judged on — counting only the four visible stems badly understates what the branches carry.
| Hidden stems | Day Master element | Ten God |
|---|---|---|
| Bing 丙 | Fire | Hurting Officer |
| Geng 庚 | Metal | Direct Officer |
| Wu 戊 | Earth | Direct Wealth |
Next Yi Si 乙巳 days
Day pillars run on a fixed 60-day cycle independent of month and year. The dates below are derived straight from the day count, so no calendar reform affects them.
- Calculating…
Where Yi Si 乙巳 sits in a chart
The day pillar is the only one read from itself — every Ten God in the year, month and hour pillars is defined relative to the Day Master Yi 乙. Two people born in the same year and month with different day stems therefore have completely different charts. In Yi Si 乙巳 the Day Master Yi 乙 is yin Wood and sits on Si 巳, which is Fire; the relation between them is Day Master produces the branch. This seat is classically read as the Day Master's immediate environment.
Related pillars
The other five pillars sharing the Day Master Yi 乙, and the other four sharing the branch Si 巳:
Same Day Master (Yi 乙)
Same branch (Si 巳)
Sources
- lunar-javascript (6tail, MIT) — solar-term instants, 干支 pillars, 大運/流年, 胎元/命宮/身宮 and the almanac tables.
- Hong Kong Observatory, Date and Time of the 24 Solar Terms — the reference used to check solar-term instants.
- Xieji Bianfang Shu and Sanming Tonghui — classical sources for the Wuhu Dun and Wushu Dun stem rules, hidden stems and the Ten Gods.
Algorithms last checked: 2026-07 · Method and accuracy