Stems & Branches: The 22-Character Alphabet
ASCII Has 128 Characters. BaZi Has 22.
Every piece of written text you're reading right now is encoded in some character set. ASCII uses 128 characters to represent the full range of printable text in English. Chinese Unicode includes tens of thousands.
BaZi uses 22.
Ten Heavenly Stems (天干, Tiān Gān) + Twelve Earthly Branches (地支, Dì Zhī) = the complete alphabet from which every BaZi chart is built.
Understanding these 22 characters is the core literacy task of BaZi study. Once you know them, the chart stops being a grid of foreign symbols and starts being readable text.
The Ten Heavenly Stems
The Stems are the "visible" characters — the outward expression layer of each pillar.
| Stem | Polarity | Element | Archetype | One-Line Profile |
|---|---|---|---|---|
| 甲 (Jiǎ) | Yang | Wood | Ancient Oak | Principled leader; needs to grow or stagnates |
| 乙 (Yǐ) | Yin | Wood | Ivy Vine | Resourceful adapter; finds every gap and grows through it |
| 丙 (Bǐng) | Yang | Fire | The Sun | Warm, generous presence; public-facing, naturally visible |
| 丁 (Dīng) | Yin | Fire | Candlelight | Focused, precise illuminator; intense depth in a small radius |
| 戊 (Wù) | Yang | Earth | Mountain | Immovable reliability; carries weight others can't |
| 己 (Jǐ) | Yin | Earth | Fertile Soil | Quiet nurturer; makes things grow without needing credit |
| 庚 (Gēng) | Yang | Metal | Sword | Direct, decisive, cuts through; impatient with inefficiency |
| 辛 (Xīn) | Yin | Metal | Gemstone | Refined, sensitive to quality; self-critical, high aesthetic sense |
| 壬 (Rén) | Yang | Water | Ocean | Vast intellect; holds contradictions without forcing resolution |
| 癸 (Guǐ) | Yin | Water | Rainfall | Quietly pervasive; gets everywhere, nurtures without fanfare |
The Stems cycle in order: 甲 (Jiǎ) → 乙 (Yǐ) → 丙 (Bǐng) → 丁 (Dīng) → 戊 (Wù) → 己 (Jǐ) → 庚 (Gēng) → 辛 (Xīn) → 壬 (Rén) → 癸 (Guǐ) → 甲 → ...
Your Day Stem is your character in this cast. Everything else in your chart is interpreted relative to it.
In your Astrobloom chart, the top character in the Day (third) column is your Day Stem. That's "you" in the BaZi framework. How the other seven characters relate to yours determines most of the chart's interpretation.
The Twelve Earthly Branches
The Branches are the "hidden" layer — each one contains one or more Stems concealed within it (called "Hidden Stems" or 藏干, Cáng Gān). They're also associated with the 12 animals of the Chinese zodiac.
| Branch | Animal | Polarity | Primary Element | Month | Hours |
|---|---|---|---|---|---|
| 子 (Zǐ) | Rat | Yang | Water | Dec | 23:00–01:00 |
| 丑 (Chǒu) | Ox | Yin | Earth | Jan | 01:00–03:00 |
| 寅 (Yín) | Tiger | Yang | Wood | Feb | 03:00–05:00 |
| 卯 (Mǎo) | Rabbit | Yin | Wood | Mar | 05:00–07:00 |
| 辰 (Chén) | Dragon | Yang | Earth | Apr | 07:00–09:00 |
| 巳 (Sì) | Snake | Yin | Fire | May | 09:00–11:00 |
| 午 (Wǔ) | Horse | Yang | Fire | Jun | 11:00–13:00 |
| 未 (Wèi) | Goat | Yin | Earth | Jul | 13:00–15:00 |
| 申 (Shēn) | Monkey | Yang | Metal | Aug | 15:00–17:00 |
| 酉 (Yǒu) | Rooster | Yin | Metal | Sep | 17:00–19:00 |
| 戌 (Xū) | Dog | Yang | Earth | Oct | 19:00–21:00 |
| 亥 (Hài) | Pig | Yin | Water | Nov | 21:00–23:00 |
The Branches cycle continuously: 子 (Zǐ) → 丑 (Chǒu) → 寅 (Yín) → ... → 亥 (Hài) → 子 → ...
Notice that four Branches carry Earth (丑 Chǒu, 辰 Chén, 未 Wèi, 戌 Xū) — these are the seasonal transition months, the "changing gears" points between seasons. Earth stabilizes transitions.
How They Combine: The 60-Year Cycle
Now the interesting part. The Stems cycle in 10, the Branches in 12. Their least common multiple is 60.
Pair them in order (Yang Stem + Yang Branch, Yin Stem + Yin Branch):
- Cycle 1: 甲子 (Jiǎ Zǐ) — Yang Wood + Yang Water
- Cycle 2: 乙丑 (Yǐ Chǒu) — Yin Wood + Yin Earth
- Cycle 3: 丙寅 (Bǐng Yín) — Yang Fire + Yang Wood
- ...
- Cycle 60: 癸亥 (Guǐ Hài) — Yin Water + Yin Water → returns to 甲子 (Jiǎ Zǐ)
This is the 60 Jiǎzǐ Cycle (六十甲子, Liù Shí Jiǎ Zǐ) — a complete rotation of the Stem-Branch combination space. It's why 60 is a culturally significant age in Chinese tradition: you've lived through one complete cycle of time.
Each of those 60 combinations has a distinct character — a specific blend of elemental energies that colors any time period (year, month, day, hour) it governs. Your four pillars are four such combinations, drawn from the exact moment of your birth.
A Sample Chart, Decoded
Let's practice reading. Here's a sample chart with the Day pillar highlighted:
Chart legend: Stems — 甲 (Jiǎ, Yang Wood), 丙 (Bǐng, Yang Fire), 壬 (Rén, Yang Water), 庚 (Gēng, Yang Metal). Branches — 子 (Zǐ, Rat/Water), 寅 (Yín, Tiger/Wood), 午 (Wǔ, Horse/Fire), 申 (Shēn, Monkey/Metal).
- Year pillar (甲子 Jiǎ Zǐ): Yang Wood Stem on Yang Water Branch. Strong upward energy; Water nourishing Wood.
- Month pillar (丙寅 Bǐng Yín): Yang Fire Stem on Yang Wood Branch. Wood fueling Fire — amplified expression, high visibility.
- Day pillar (壬午 Rén Wǔ) — This person's "self": Yang Water Stem on Yang Fire Branch. Water and Fire on the same pillar create interesting tension — intellectual depth (Water) needing to reconcile with visible passion (Fire).
- Hour pillar (庚申 Gēng Shēn): Yang Metal Stem on Yang Metal Branch. Double Metal — decisive, structured, high standards for their own output.
Even this quick scan tells you something about the person's internal dynamics.
Summary
- 10 Heavenly Stems = the visible layer; 5 elements × 2 polarities
- 12 Earthly Branches = the hidden layer; linked to months, hours, zodiac animals, and concealed Stems
- They combine into a 60-unit cycle — each combination unique
- Your four pillars are four of these 60 combinations, defining the "timestamp" of your birth
- Your Day Stem is the character representing you in the chart
Next article: how to actually read the Four Pillars — what each column says about different life domains, and how to identify the most important signals in your chart.