What Is BaZi? The Four Pillars Explained

BaZi (八字, "eight characters") records a birth moment as four pairs of Chinese calendar symbols: the year, month, day and hour pillars. Each pillar combines one heavenly stem and one earthly branch, giving eight characters in total. The method is also called the Four Pillars of Destiny (四柱命理) and has been practised in roughly its current form for about a thousand years.

This article explains the building blocks, how a chart is calculated, how practitioners read it and — just as important — what a chart cannot do. If you want to follow along with your own data, open the free BaZi calculator in another tab.

A short history

Calendar cycles of stems and branches are far older than BaZi itself; they were used to count days in the Shang dynasty more than three thousand years ago. Early "destiny" methods focused on the year of birth. The decisive change came in the Song dynasty, when the approach associated with 徐子平 (Xu Ziping) made the day stem the centre of the chart. That stem, now called the Day Master, represents the person, and every other symbol is read in relation to it.

Later works built on that foundation. 渊海子平 collected the Song method, 三命通会 (Ming) compiled a vast amount of material, and 滴天髓 and 子平真诠 developed the analytic approaches most modern teachers still use: judging strength and choosing a useful element, and classifying charts by structure.

Stems, branches and the sixty cycle

The ten heavenly stems are the yin and yang forms of the five elements:

The twelve earthly branches — 子 丑 寅 卯 辰 巳 午 未 申 酉 戌 亥 — mark months, two-hour periods and directions. Unlike stems, each branch contains one to three hidden stems, so a branch is a small bundle of elements rather than a single one. See earthly branches for each branch in detail.

Pairing stems and branches in order (yang with yang, yin with yin) gives sixty combinations, from 甲子 to 癸亥. This sexagenary cycle counts years, months, days and hours, so every pillar in a chart is one of those sixty pairs.

How a chart is calculated

Calculating a chart means converting a birth moment into four pillars. The rules are fixed, but the boundaries are where most errors happen:

• Year — the BaZi year begins at the exact moment of 立春 (Start of Spring, around 4 February), not on 1 January and not at Chinese New Year. Someone born on 25 January usually belongs to the previous BaZi year. See Li Chun and the BaZi year.
• Month — months begin at the twelve jie solar terms (节). The 寅 month starts at 立春, 卯 at 惊蛰, and so on. They are not lunar months. See solar terms.
• Day — the day pillar comes from an unbroken sixty-day count. By default the day changes at 23:00 at the start of the 子 hour; some schools change at midnight. See Zi hour: 23:00 vs 00:00.
• Hour — twelve two-hour periods, judged by the sun. Many practitioners therefore convert clock time to true solar time.

Here is an example chart calculated with these rules:

Our methodology lists every boundary rule we use, and the result page shows the time zone, the solar-time correction and the governing solar term so you can verify each pillar.

What practitioners read

Once the pillars are correct, a reading usually proceeds in layers:

1. The Day Master — its element and polarity. There are ten Day Masters.
2. Season and strength — the month branch decides which element is in command. Together with roots in the branches, it tells you whether the Day Master is strong or weak. See judging Day Master strength.
3. The Ten Gods — every other stem is named by its relation to the Day Master: companions, output, wealth, officer or resource. See the Ten Gods.
4. Combinations and clashes — fixed pairs of stems and branches bind or oppose each other. See combinations and clashes.
5. Useful element — the element that best balances the chart, chosen by one of several methods. See finding the useful element.
6. Timing — ten-year luck pillars and yearly annual pillars are read against the natal chart.

Each layer builds on the one before. Skipping straight to timing without judging strength is the most common beginner mistake.

A first look at the example chart

In the example above, the day pillar is the reference point. Find the highlighted day stem — that is the Day Master — and note its element. Then look at the month branch directly beside it: is it the same element as the Day Master, an element that feeds it, or one that drains or controls it? That single comparison is the first estimate of strength.

Next, scan the hidden stems listed under each branch. Any hidden stem of the same element as the Day Master is a root; roots in the month and day branches count most. Finally, read the small labels above the other three stems: these are their Ten Gods. If most of them are companions and resources, the chart leans strong; if most are output, wealth and officers, it leans weak.

Every branch's hidden stems follow a fixed table:

None of this is interpretation yet — it is simply reading the structure. But it is the structure that every later judgement rests on, and the calculator shows it all on one screen.

What the five elements mean here

Wood, fire, earth, metal and water are better understood as five phases of change than as five substances. Wood generates fire, fire generates earth, earth generates metal, metal generates water and water generates wood; wood controls earth, earth controls water, water controls fire, fire controls metal and metal controls wood. Every relation in a chart — every Ten God, every judgement of strength — is an application of these two cycles. Read more in five elements in BaZi.

What a chart is not

A BaZi chart is a structured description used in a long cultural tradition of reflection and advice. It is reproducible: two careful practitioners using the same conventions will draw the same eight characters. But interpretation is not a measurement, and there is no scientific evidence that charts predict events. Treat it as a vocabulary for thinking about tendencies, timing and balance — not as instructions for medical, legal or financial decisions.

A few common misconceptions are worth clearing up:

• "BaZi is the Chinese zodiac." The popular birth-year animal is only one branch out of eight characters. This site focuses on stems, branches and elements.
• "A missing element must be added." A missing element may be irrelevant; balance is judged relative to the Day Master and season.
• "Clashes are bad luck." Clashes describe movement and friction; whether that helps or hurts depends on the whole chart.

How to start learning

The fastest way to learn BaZi is to calculate a few charts — your own, family members' with known birth times — and work through the layers above with the reference pages open:

• Start with What are the Four Pillars of Destiny? and How to read a BaZi chart.
• Keep the glossary open for unfamiliar terms.
• Use the FAQ when a result surprises you.

Key terms in this article

Four Pillars · 四柱

The Four Pillars are the year, month, day and hour of birth, each written as a heavenly stem over an earthly branch. Together they give eight characters, which is why the method is also called BaZi (八字, "eight characters"). The pillars are derived from the solar calendar of solar terms, not from the lunar month.

Sexagenary Cycle · 六十甲子

Pairing the ten stems with the twelve branches in order (yang with yang, yin with yin) gives sixty combinations, from 甲子 to 癸亥. The same cycle counts years, months, days and hours, which is why every pillar is one of these sixty pairs.

Start of Spring (Li Chun) · 立春

立春, when the sun reaches 315° ecliptic longitude around 4 February, begins the BaZi year and the 寅 month. Someone born on 1 February belongs to the previous BaZi year even if Chinese New Year has passed — or not passed.

Day Master · 日主

The Day Master (日主 or 日元) is the heavenly stem of the day pillar. It represents the self in the chart, and every other stem is named relative to it as one of the Ten Gods. Its strength, judged mainly from the month branch and roots, is the starting point of nearly every reading.

Frequently asked questions

Do I need my birth time? It helps, because it sets the hour pillar. Without it, the other three pillars are still usually reliable; see unknown birth time.

Why does my year differ from my Chinese New Year year? Because BaZi changes year at 立春. Births between the two dates differ.

Is BaZi the same as Zi Wei Dou Shu? No — both use birth data, but Zi Wei places stars in twelve palaces. See BaZi vs Zi Wei Dou Shu.

Next: read about the Day Master, or calculate your chart.