Stems and branches: the alphabet of BaZi.

A BaZi chart is eight characters, and every one of them is drawn from just two small sets of symbols: ten Heavenly Stems (天干) and twelve Earthly Branches (地支). Learn these two alphabets and a chart stops looking like code. Each pillar is simply one stem written over one branch.

The ten Heavenly Stems (天干)

The stems are the five elements in their yang and yin forms — two of each, ten in all. A stem is clean and direct: one element, one polarity. When the Heavenly Stem of your day pillar is one of these, it is your Day Master.

The twelve Earthly Branches (地支)

The branches are the twelve signs that also name the zodiac animals. Each carries a main element and a season — but a branch is never as simple as a stem, because each one also hides one to three stems inside it.

The sixty-year cycle (六十甲子)

Now pair them. Put the first stem over the first branch — 甲子 — then advance both by one, and one, and one. Because ten and twelve do not line up evenly, the pairing does not repeat until you have run through sixty unique stem-and-branch combinations. That is the Jia Zi (甲子), the sixty-year cycle, and it stamps every year, month, day, and hour with one of those sixty pairs.

This is also why a polarity rule holds throughout a chart: a yang stem only ever meets a yang branch, and yin only meets yin — the mismatched halves never pair, which is exactly what leaves sixty combinations rather than 120.

Heaven above, earth below

Why two alphabets instead of one? Tradition reads the stems as heaven's qi — clearer, quicker, more outward — and the branches as earth's qi — slower, mixed, holding things hidden beneath the surface. A pillar puts one over the other, and the interplay between the visible stem and the layered branch is much of what gives a chart its depth.

Keep going: the hidden stems inside each branch, yin and yang, the five elements, or your Day Master's strength.