What is BaZi (Four Pillars)? — how four stem–branch pairs are built from a birth moment
1. The idea in one paragraph
A birth moment is first converted into calendar coordinates: which solar year, which solar term, which day number, which double-hour. Those coordinates are then written in a two-character-per-position notation, so four positions produce eight characters. From there the framework does one more thing — it names the relations between those characters, using the five phases (五行) and polarity (阴阳). Everything on this site follows from that: conversion, notation, relation naming. There is no hidden step in which a message is received.
2. Stems, branches and the sexagenary cycle (干支)
- Ten heavenly stems (天干): 甲 乙 丙 丁 戊 己 庚 辛 壬 癸 — each with a phase (wood, fire, earth, metal, water) and a polarity (yang or yin).
- Twelve earthly branches (地支): 子 丑 寅 卯 辰 巳 午 未 申 酉 戌 亥 — each with a phase, a polarity, a season and one to three hidden stems (藏干).
- Pairs and cycles: a stem is paired with a branch to give a two-character unit (干支). Because ten stems and twelve branches advance together, the pairing repeats every 60 combinations (六十甲子) rather than every 10 or 12.
- Boundaries are conventions: the year changes at Lichun (立春), the month at solar terms (节气). Both are stated because different conventions yield different charts from identical birth data.
3. The four pillars and the Day Master
| Pillar | Read from | What the tradition assigns to it |
|---|---|---|
| Year (年柱) | Birth year, changing at Lichun | The wider setting — era, family background, early years |
| Month (月柱) | Birth month, changing at solar terms | Season and environment; also the source of the luck-pillar sequence |
| Day (日柱) | Birth day; the day stem is the Day Master (日主) | The reference point of the whole chart — "me" in the notation |
| Hour (时柱) | The double-hour of birth, stem derived by the Five Rats Escape rule (五鼠遁) | Later life and the people closest in the household |
Two clarifications about that third column. The meanings are the framework's own conventions, not findings about a person, and this site does not use them to assert anything about anyone's life. And the Day Master is not a "type": it is simply the stem that all other labels are measured against, so the same stem can carry different labels in two different charts.
4. From phases to the Ten Gods (十神)
Once there is a Day Master, each remaining stem is classified by two questions: how its phase relates to the Day Master's phase (same, produced by me, controlled by me, controlling me, or producing me), and whether its polarity is the same as or opposite to the Day Master's. Five relations × two polarities gives ten labels — the Ten Gods (十神). They are relation names, not deities.
| Relation | Same polarity | Opposite polarity |
|---|---|---|
| Same phase — peers (比劫) | 比肩 Peer | 劫财 Rival |
| The phase I produce — output (食伤) | 食神 Eating God | 伤官 Hurting Officer |
| The phase I control — wealth (财) | 偏财 Indirect Wealth | 正财 Direct Wealth |
| The phase that controls me — officers (官杀) | 七杀 Seven Killings | 正官 Direct Officer |
| The phase that produces me — resources (印) | 偏印 Indirect Resource | 正印 Direct Resource |
The full derivation, the polarity logic and worked examples from two Day Masters are on The Ten Gods (十神) explained. Labels are attached to the visible stems, to the hidden stems inside each branch, and to the stems of luck pillars and yearly flow.
5. Luck pillars, yearly and monthly cycles
- Luck pillars (大运): a ten-year sequence laid out from the month pillar, forward or backward depending on year-stem polarity and gender, with the starting age computed as days to the adjacent solar term ÷ 3.
- Yearly flow (流年): the stem and branch of a civil year, read against the natal chart — which positions it activates and which relations it forms.
- Monthly flow (流月): the same reading for each of the twelve months of a chosen year; the site renders it as a twelve-row table.
- Energy curve: a deterministic rhythm score built from the month's Ten God plus branch relations (repetition, clash, combination). It is presented as a pacing aid for output versus consolidation — not a luck forecast.
- Zi Wei Dou Shu is separate: the same birth data also yields a Zi Wei chart with twelve palaces and ten-year decades (大限). The two systems share the Lichun year boundary but nothing else, and the site never blends their outputs.
6. How to use BaZi without fortune-telling
If the notation can be recomputed, it can also be checked — that is the only serious way to use it. Two mechanisms exist on this site for that purpose:
- Backwards: enter real events from recent years and see whether the chart's yearly relations harmonise with them. A match is called resonance, not destiny; a miss is information too, because it means the framework explains less for you.
- Forwards: dated statements are recorded with a time window and later marked met / partly met / not met, so you build your own hit-rate rather than trusting a slogan.
Scope: this site is for entertainment and cultural study only. It presents BaZi as a traditional symbolic framework, not a science, and it makes no predictions and no claims about your future, health, money or relationships. Take the notation and the rules; leave the claims to whoever wants to make them.
Frequently asked questions
Is BaZi the same as the Chinese zodiac?
No. The zodiac (生肖) uses the year branch alone, so it changes once a year and everyone born in that year shares it. A BaZi chart uses eight characters — a stem and a branch for each of four positions — and its most sensitive input, the hour, changes every two hours. The two are related, but the zodiac is a small slice of the notation.
What is the Day Master (日主)?
The stem of the day pillar. It is the fixed reference point of a BaZi chart: every other stem, including those hidden inside branches, is labelled by its relation to it (the Ten Gods). It is not a personality type and does not by itself determine a reading.
Do I need my exact birth time?
Yes, to the double-hour. The form offers 13 slots, from early-Zi (00:00–01:00) through 亥 (21:00–23:00) to late-Zi (23:00–24:00), and the hour pillar drives the Zi Wei life palace and body palace as well. An "hour unknown" mode is not offered, because it would quietly produce a different chart.
Does BaZi predict the future?
Not here. This site computes charts deterministically and translates published rules into plain language, for entertainment and cultural study only. It makes no predictions and no claims, and it does not assert scientific validity. Whether the framework has explanatory power for you is something its past-event validation is meant to let you judge yourself.
Related entries
Want to see the four pillars for your own birth data?
See also：Computation method · Computation rules · Pricing