The Ten Heavenly Stems (天干)
Ten characters, five elements, two polarities.
In short
The ten heavenly stems (天干, tiān gān) are a fixed sequence of ten characters, 甲 乙 丙 丁 戊 己 庚 辛 壬 癸, that label the top half of every pillar in a Bazi chart. They are the five elements doubled: each element appears once in a yang form and once in a yin form.
| Characters | 天干 |
|---|---|
| Pinyin | tiān gān |
| Group | Foundations |
The stems carry the element and the polarity of a pillar. The branches underneath carry the season and the time. A pillar is one of each, so a full chart is eight characters drawn from two alphabets of ten and twelve.
The stems are older than the charts. They appear on Shang dynasty oracle bones, where they were used to count days in a repeating cycle, and the twelve branches were used the same way. Only later were the two sequences run together to make the sixty-day cycle, and later still were they applied to the year, month, day, and hour of a birth.
Ten and twelve share a lowest common multiple of sixty, which is where the sixty-year cycle comes from. Pair a stem with a branch and step both forward one at a time, and you return to the start after sixty moves. That is the same cycle the zodiac animal years run on, and it is why the year 2027 is 丁未 rather than any other fire and earth combination.
Each stem has a set of correspondences that go beyond the chart: a direction, a season, an organ, a colour. 甲 is yang wood and reads as a tall tree, 乙 as yin wood and reads as a vine or grass. The two share an element and behave quite differently, which is the point of having polarity as a separate axis.
The ten stems
Five elements, each appearing once in a yang form and once in a yin form. 甲 is the first stem and the one most often used in examples, partly because early texts use it the way English uses "item one".
| Stem | Element | Polarity |
|---|---|---|
| 甲 jiǎ | Wood | Yang |
| 乙 yǐ | Wood | Yin |
| 丙 bǐng | Fire | Yang |
| 丁 dīng | Fire | Yin |
| 戊 wù | Earth | Yang |
| 己 jǐ | Earth | Yin |
| 庚 gēng | Metal | Yang |
| 辛 xīn | Metal | Yin |
| 壬 rén | Water | Yang |
| 癸 guǐ | Water | Yin |
Definitions get you through a chart. Something has to be done with it.
The audit walks the nine areas of a home in the order that matters, with two or three changes per area. It is the practical half of what these terms describe.
Questions people ask about this term
What is the difference between a heavenly stem and an earthly branch?
A stem sits on top and a branch sits underneath in each pillar. The stem carries element and polarity; the branch carries a season, a zodiac animal, and a two-hour window. Neither is more important, and a reading needs both before it can say anything.
Why are there ten stems and twelve branches?
The stems come from the five elements times two polarities, which is ten. The branches come from the twelve months of the solar year, which is twelve. Stepping both forward together returns to the starting pair after sixty moves, since sixty is the lowest number both divide into.
Which stem is my day master?
The stem of your day pillar. It is the one character among the eight that stands for you, and every other stem in the chart gets its ten god name from how it relates to it. A calculator will show it in the third column of the chart.
This page has no affiliate links and nothing to sell. The tables here are fixed by the tradition and you can check any of them against a printed almanac. What a chart means for a person is a reading of that tradition, not a finding, so treat it as a way to think about a situation rather than a prediction.