BaZi marriage compatibility — 合婚 — is one of the oldest applications of the four pillars. Before a modern reader checks anything else, it's worth knowing what the method actually looks at, and what it can reasonably claim.
1. What a compatibility reading actually checks
1.1. Day Masters — the couple's core chemistry
The Day Master is the element of your birth-day stem, and it sets the baseline of personality. The five pairs interact in a cycle of generating and controlling:
- Wood and Fire — generating: one fuels the other's enthusiasm.
- Fire and Earth — generating: warmth that settles into stability.
- Earth and Metal — generating: structure that sharpens into direction.
- Metal and Water — generating: discipline that channels ambition.
- Water and Wood — generating: strategy that grows into action.
Controlling pairs (Wood–Earth, Fire–Metal, Earth–Water, Metal–Wood, Water–Fire) aren't "bad" — they read as push-and-pull. Many long marriages are controlling pairs; the friction is also a check and balance.
1.2. The earthly branches — the year and day of birth
The second layer looks at the twelve animal branches of the birth year and birth day. Traditional tables highlight pairings believed to clash or harmonize — for example, the six 冲 (clashes) and six 合 (combinations). A reader weighs these alongside the element analysis, never in isolation.