At the moment you were born, the traditional Chinese calendar was pointing at four positions at once — a year, a month, a day and an hour. Written in the calendar’s own notation, each position takes two characters. Four positions, eight characters: that is your BaZi 八字, literally “eight characters”, also known as the Four Pillars 四柱. This guide explains what the chart is made of, how to read its centre, and what a reading can and cannot tell you.
Eight characters from one moment
BaZi begins from a simple fact about the traditional calendar: it does not name moments with numbers, it names them with characters. Each of the four pillars — year 年, month 月, day 日, hour 時 — is written as a pair: a heavenly stem 天干 above and an earthly branch 地支 below. Transcribe your birth moment and you get a small grid of eight characters, like this one:
That grid is fixed. It does not update, and no one can edit it. Everything in a BaZi reading is a way of looking at those same eight characters from different angles — which is part of the appeal. The text is short; people spend lifetimes reading it.
Stems, branches and the five elements
There are ten heavenly stems and twelve earthly branches. You have met the branches already: they are the zodiac animals. “Born in the year of the Dragon” simply means the branch of your year pillar is 辰, the Dragon.
Every stem and branch maps to one of the five elements 五行 — Wood 木, Fire 火, Earth 土, Metal 金, Water 水 — in a yang (active) or yin (receptive) form. The tradition gives each pairing its own image: Yang Wood 甲 is a standing tree, Yin Wood 乙 a climbing vine; Yang Fire 丙 is the sun, Yin Fire 丁 a lamp flame. So your eight characters are also a recipe of elements: perhaps heavy in water, missing fire, with one stubborn seam of metal running through the middle.
The elements relate in cycles — wood feeds fire, fire makes earth, earth bears metal, metal carries water, water grows wood — and each element also keeps another in check. A reading is essentially ecology: what is abundant in this chart, what is scarce, what feeds what, and what holds what back.
The Day Master 日主 — a worked example
Of the eight characters, one is you: the stem of the day pillar, called the Day Master 日主. Everything else in the chart is read in relation to it. In the example chart above, the day pillar is 庚申 — so the Day Master is Yang Metal 庚金.
Yang Metal is the metal of ore, axes and blades — raw, structural metal, as opposed to Yin Metal 辛金, the metal of jewellery and fine wire. Read as a temperament, 庚金 suggests someone direct, durable and slow to bend: a person of edges and commitments, more at home cutting through a problem than talking around it.
Then the ecology matters. In the five-element cycle, fire controls metal — and for Yang Metal that is not a threat but a forge. A 庚金 chart with fire present (this one has a 丙 Fire month stem) reads as someone tempered by pressure: challenge refines them rather than wearing them down. The same chart with no fire at all might read as strength that never quite gets shaped — plenty of raw material, waiting for heat.
The other pillars fill out the picture. This chart’s hour pillar is 壬子 — Yang Water over the Rat, water on water. In the cycle, metal carries water: the tradition reads water here as the Day Master’s output, its expression. Strong metal producing abundant water suggests someone whose bluntness eventually finds a channel — a maker, a writer, a builder of systems. That is one reading among several; the point is that the pillars are read together, not one by one.
Notice what this kind of reading is: a sketch of tendencies, told in the tradition’s own metaphors. It does not say which career to choose or whom to marry. It offers a vocabulary — “this is a chart that improves under pressure” — that you can test against your own experience.
What a reading covers — and what it doesn’t
A full reading looks at the balance of elements across the chart, the character of the Day Master, and the relationships between the pillars — traditionally the year speaks of roots and ancestry, the month of upbringing and working life, the day of the self and marriage, the hour of later years. It also looks at the luck pillars 大運: ten-year chapters that layer a new pair of characters over your chart, so the same person meets different weather in different decades.
The luck pillars are worth pausing on, because they answer the most common objection — “if the chart is fixed, why does life change?” In this system the chart is the instrument and the decades are the music played through it. A fire decade arriving over our 庚金 chart is the forge lit; a damp, watery decade is the same steel asked to do quieter work. Nothing about you was rewritten. The weather turned.
What it does not cover is certainty. A chart is not a verdict, and no honest reading promises outcomes — tendencies, not guarantees. We treat BaZi as a mirror and a vocabulary for self-reflection: a cultural inheritance, not a clinical instrument, and never a substitute for financial, medical or professional advice.
Where BaZi meets daily life is timing. The almanac — the Tung Shing 通勝 — describes the character of each day for everyone; your chart describes you. Traditional date-picking works at the intersection: start from the almanac’s good days — say, the wedding dates for 2026 — then keep the ones that also sit well with the charts of the people involved. You can see what a general day looks like on today’s almanac.
What if you don’t know your birth time?
The hour pillar needs your birth time, and many people simply do not have it — old records, family memory, a hospital that never wrote it down.
The chart degrades gracefully. Without the hour you still have six of the eight characters: the Day Master is intact, the elemental balance is mostly readable, and the year and month pillars still frame the picture. You lose the traditional “later years” corner and some precision — not the reading itself.
Xuan Lab handles this honestly: if the time is unknown, the hour pillar is left blank, never guessed. And one privacy note we consider non-negotiable — birth time is used for computation only. It is never displayed anywhere in the app, to you or to anyone else.
If you do track the time down later — a birth certificate, a hospital record, a parent’s memory of “just before dinner” — you can add it and the chart simply completes itself. The six characters you already had do not move.