What is saju?

Saju (사주, 四柱) means "four pillars". It is a way of describing a person through the moment they were born: the year, month, day and hour. Each pillar is written with two characters, so a full chart has eight characters, called saju palja (사주팔자). In China the same system is called BaZi (八字), and in English the Four Pillars of Destiny.

The method took shape in China around a thousand years ago; the scholar Xu Ziping of the Song dynasty is credited with making the day stem the center of the reading, which is why classical BaZi is also called the Ziping method. It spread to Korea, where it became part of everyday culture. Today Korean saju apps have tens of millions of users, and "saju cafés" are a popular night out in Seoul.

The building blocks

Ten heavenly stems

The stems are the five elements in yin and yang form: 甲 Gap, 乙 Eul, 丙 Byeong, 丁 Jeong, 戊 Mu, 己 Gi, 庚 Gyeong, 辛 Sin, 壬 Im, 癸 Gye.

Twelve earthly branches

The branches are the familiar zodiac animals, each linked to an element and a season, and each holding one to three "hidden stems": 子 rat, 丑 ox, 寅 tiger, 卯 rabbit, 辰 dragon, 巳 snake, 午 horse, 未 goat, 申 monkey, 酉 rooster, 戌 dog, 亥 pig.

Sixty pillars

Pairing stems and branches in order gives a cycle of 60 combinations (육십갑자, the sexagenary cycle). Years, months, days and hours all run through this cycle. 2026, for example, is 丙午, the Fire Horse.

The five elements

Wood feeds Fire, Fire creates Earth, Earth bears Metal, Metal carries Water and Water nourishes Wood. In the other direction, Wood breaks Earth, Earth dams Water, Water puts out Fire, Fire melts Metal and Metal cuts Wood. A saju reading is largely about how these forces are balanced in your chart.

Your Day Master

The heavenly stem of your birth day is your Day Master (일간, 日干). It represents you; everything else in the chart is read in relation to it. A Yang Wood person is a tall tree; a Yin Water person is rain and dew. Meet the ten Day Masters →

The ten gods

Every other character gets a role relative to your Day Master: peers, expression, wealth, authority or support. These "ten gods" (십신) explain why two people with the same Day Master can be so different: one has a chart full of creative output, another a chart full of discipline and responsibility.

Luck cycles

Your chart also unfolds in time. Ten-year luck pillars (대운) begin a few years after birth, and each year (세운) and month brings its own pillar that interacts with yours. That is why a reading changes from year to year.

How Sajuwise calculates your chart

• Year and month pillars change at the 12 "jie" solar terms, which Sajuwise computes from the Sun's position to the minute. The year begins at Lichun, around February 4, not on January 1 or Lunar New Year.
• The day pillar counts days from a fixed reference using the Julian day number, so 1 January 2000 is a 戊午 day.
• The hour pillar follows the two-hour branches. You can optionally correct it to true local solar time using your birth city's longitude and the equation of time.
• Time zones and daylight saving, including historical rules such as Korea's 1987–88 summer time, are handled with the standard time-zone database.

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