How Stems and Branches Form a Bazi Chart (天干地支)
Understand how ten Heavenly Stems and twelve Earthly Branches combine into sixty valid pairs and supply the year, month, day, and hour of a Bazi chart.
Overview
Bazi uses ten Heavenly Stems and twelve Earthly Branches in a fixed sexagenary sequence of sixty valid pairs. One pair is assigned to each of the four pillars. Stems show a visible phase and polarity; branches carry their own phase, seasonal position, hidden stems, and relation rules. They are complementary data layers, not interchangeable labels.
At a glance
- Heavenly Stems
- 10 symbols
- Earthly Branches
- 12 symbols
- Valid pair cycle
- 60 Jiazi combinations
- Pillar count
- Four stem-branch pairs
- Branch contents
- Phase, season, hidden stems, and relations
- Pairing limit
- Not every one of 120 possible pairings is valid
The two sequences advance together
Stems cycle every ten positions and branches every twelve. Advancing them together returns to the starting pair after sixty steps.
Parity is preserved, so yang stems pair with yang branches and yin stems with yin branches. A valid chart pillar must belong to this sixty-pair sequence.
- Validate every pillar against the Jiazi cycle.
- Do not choose stems and branches independently.
Stems and branches expose different information
A Heavenly Stem is a visible phase-polarity symbol used directly in Ten God and stem-interaction analysis.
An Earthly Branch is also a phase and polarity symbol, but additionally represents a seasonal position and contains canonical hidden stems. Its relation tables differ from stem rules.
- Keep stem and branch rule sets separate.
- Expand hidden stems only from the branch table.
Four pairs describe four time resolutions
Year and month pillars depend on solar-term boundaries, the day pillar follows a continuous day cycle, and the hour pillar depends on the effective local time and Day Stem.
Because later calculations depend on earlier results, correcting one boundary can change more than one displayed field. Recompute rather than patching a single label.
- Record each pillar’s derivation.
- Recalculate all dependent data after a correction.
Symbols are not literal objects or people
Wood, Fire, Earth, Metal, and Water are technical phase categories, not measurements of physical substances in the body or environment.
Stem and branch names organize a traditional model. Their presence alone cannot establish character, profession, diagnosis, or future events.
- Use phase language, not literal material claims.
- Require context before interpretation.
Sources and editorial basis
- Hong Kong Observatory: Heavenly Stems and Earthly Branches十天干、十二地支與六十循環：干支對的排列規則An official modern reference for the canonical stem and branch orders, the sexagenary cycle, and calendrical use.
- 《三命通會》 (Sanming Tonghui)《三命通會》卷二干支配合諸論：干支上下層與藏氣不可混同A historical compilation covering stems and branches, Ten Gods, Nayin, Shen Sha, and multiple classical pattern systems.
- OpenFate Editorial Methodology干支成盤頁說明計算、實體映射與解釋欄位的可稽核邊界OpenFate separates deterministic chart calculation, traditional interpretation, and modern editorial explanation.