Heavenly Stems and Earthly Branches — The 60-Year Cycle
All ten heavenly stems and twelve earthly branches, with elements, yin/yang, hours and animals — and why the sexagenary cycle is sixty long.
What are heavenly stems and earthly branches?
Ten heavenly stems and twelve earthly branches combine in a sixty-step cycle, which is the calendar BaZi is built on. A stem gives the visible, active quality of a period; the branch underneath it gives the season, the element and the hidden stems.
The ten heavenly stems
| Stem | Element | Yin/Yang | Character |
|---|---|---|---|
| Jia 甲 | Wood | Yang | The first stem: a seed breaking through. Jia people grow straight and fast, and are better at starting than at bending. |
| Yi 乙 | Wood | Yin | The second stem: the vine. Yi people are flexible, persuasive and grow around obstacles rather than through them. |
| Bing 丙 | Fire | Yang | Sunlight. Bing people are visible, warm and hard to ignore — they energise a room simply by arriving. |
| Ding 丁 | Fire | Yin | Candlelight. Ding people are focused and refined; their influence is deep rather than wide. |
| Wu 戊 | Earth | Yang | The mountain. Wu people are steady, reliable and slow to move once they have decided. |
| Ji 己 | Earth | Yin | Farmland. Ji people absorb, nurture and make other people's ideas actually grow. |
| Geng 庚 | Metal | Yang | The blade. Geng people are decisive, principled and cut straight through noise. |
| Xin 辛 | Metal | Yin | Jewellery. Xin people are precise and tasteful, and prefer quality to volume in everything. |
| Ren 壬 | Water | Yang | A great river. Ren people think in large systems and are restless when confined to small ones. |
| Gui 癸 | Water | Yin | Morning dew. Gui people are perceptive and subtle, and read a room faster than anyone in it. |
The twelve earthly branches
The branches are the twelve animals. They also mark the twelve traditional double-hours of the Chinese day, which is why the hour pillar flips at 23:00 rather than midnight.
| Branch | Animal | Element | Yin/Yang | Hour |
|---|---|---|---|---|
| Zi 子 | Rat | Water | Yang | 23:00 – 01:00 |
| Chou 丑 | Ox | Earth | Yin | 01:00 – 03:00 |
| Yin 寅 | Tiger | Wood | Yang | 03:00 – 05:00 |
| Mao 卯 | Rabbit | Wood | Yin | 05:00 – 07:00 |
| Chen 辰 | Dragon | Earth | Yang | 07:00 – 09:00 |
| Si 巳 | Snake | Fire | Yin | 09:00 – 11:00 |
| Wu 午 | Horse | Fire | Yang | 11:00 – 13:00 |
| Wei 未 | Goat | Earth | Yin | 13:00 – 15:00 |
| Shen 申 | Monkey | Metal | Yang | 15:00 – 17:00 |
| You 酉 | Rooster | Metal | Yin | 17:00 – 19:00 |
| Xu 戌 | Dog | Earth | Yang | 19:00 – 21:00 |
| Hai 亥 | Pig | Water | Yin | 21:00 – 23:00 |
Why sixty
Ten stems and twelve branches pair up until they realign: the least common multiple is 60. So 甲子 (Jia-Zi) begins a cycle, and the same combination does not return for sixty years. Every year in the cycle has a distinct stem-branch pair — that pair is what sets the element of that specific year.
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