What BaZi is and how to read the four pillars

BaZi (八字, “eight characters”) is a way of writing a moment of birth in the traditional Chinese calendar. The calendar counts years, months, days and double hours in a sixty-step cycle, and every step is a pair of signs: a heavenly stem on top and an earthly branch below. A birth date and time therefore become four pairs, the four pillars, and eight signs in all. That is the whole chart. Everything else in the practice is a way of reading the relationships between those eight signs.

The system is traditional, not scientific. The sixty-step calendar is far older than the method: it was in use before the Zhou dynasty, while the four-pillar way of reading it for a person took shape in the Tang and Song dynasties. This page explains the structure; it does not claim anything about outcomes.

A real chart

The example throughout these materials is a woman born on 21 March 1990 at 10:30 in Madrid; the chart was calculated by the BaziArt engine with true solar time. Nothing about this chart is special; it was chosen because it illustrates several of the rules described here.

Each pillar comes from a different cycle. The year pillar changes at the start of spring in the solar calendar (around 4 February), not on 1 January. The month pillar changes at the twelve sectional solar terms, so a “month” here is about thirty days starting from a solar term, not a calendar month. The day pillar runs through the sixty-step cycle continuously, and the hour pillar divides the day into twelve double hours. All four are counted from the moment of birth converted to true solar time, which is why the place of birth matters (why).

The five elements in the chart

Every stem and every branch belongs to one of five elements: Wood, Fire, Earth, Metal, Water. A branch also holds one to three hidden stems, which is why the table above lists more than one sign under each branch. Reading a chart starts with a count: which elements are present, which are scarce, and how the season of birth weighs them.

Count of the eight visible signs in the example chart, before the hidden stems: Wood 2, Fire 2, Earth 1, Metal 3, Water 0. Water is absent from the open signs and from the hidden stems alike: the chart has none of it. The absence is noted on its own; the season and the roots are judged separately when the Day Master is weighed.

The count is not a verdict. In this system it is the starting point for the two questions that follow: which sign is the Day Master, and how much support it has.

The Day Master and the ten relations

The stem of the day pillar is called the Day Master: the sign that stands for the person. Every other sign is read by its relation to it. There are ten such relations, the ten gods: each of the five element relations (same element, what feeds it, what it produces, what it controls, what controls it) in a yang and a yin form. In the example chart the open stems of the other three pillars read like this:

• Year stem 庚: Direct Officer (正官).
• Month stem 己: Indirect Wealth (偏財).
• Hour stem 辛: Seven Killings (七殺).

The library explains every one of these relations in plain language and for practitioners, and the next material explains how the Day Master is found and how its strength is judged.

What the chart does not say

A BaZi chart is a description of a moment in a traditional calendar, read by the rules of a school. It does not state facts about a person and it does not describe the future. In the BaziArt app every rating comes with “why I see this”: the rule and the signs behind it, so that the reading stays a reading. The calculator builds a chart from your own data with the same engine.