Saju in one paragraph
Saju (사주, 四柱) means “four pillars”. It is the Korean name for the East Asian practice, also called BaZi in Chinese, of writing a birth moment as four pairs of characters: one pair each for the year, month, day and hour. Each pair is a pillar made of a heavenly stem on top and an earthly branch below, so a full chart has eight characters, which is why Koreans also call it palja (팔자, “eight characters”). Readers look at how the five elements in those characters balance, support and clash, and then tell a story about temperament, relationships and timing. In Korea, Saju is part of everyday culture: people check it at the New Year, before weddings, or just for fun.
The four pillars and what each stands for
| Pillar | Changes | Traditionally linked with |
|---|---|---|
| Year (연주) | at Ipchun, around 4 February | ancestry, social background, early childhood |
| Month (월주) | at each of 12 solar terms | parents, upbringing, career environment; the month branch sets the season, the single biggest factor for element strength |
| Day (일주) | every day, continuous 60-day cycle | you (the day stem or day master) and your spouse palace (the day branch) |
| Hour (시주) | every two hours | children, later life, private ambitions |
Because the year and month follow the 24 solar terms rather than the calendar month, someone born on 2 February belongs to the previous Saju year. The day pillar is different: it simply counts days in an unbroken 60-day cycle that has run for centuries, which is why a calculator can find it from any date.
Stems, branches and the 60 cycle
There are ten heavenly stems (Gap, Eul, Byeong, Jeong, Mu, Gi, Gyeong, Sin, Im, Gye) and twelve earthly branches (Ja, Chuk, In, Myo, Jin, Sa, O, Mi, Sin, Yu, Sul, Hae), the branches being the familiar zodiac animals. They advance together, one step at a time: Gap-Ja, Eul-Chuk, Byeong-In… Because 10 and 12 share a factor of 2, a yang stem always meets a yang branch and a yin stem a yin branch, so only 60 of the 120 possible pairs exist. That is the 60 Gapja, the same cycle that names years such as 2027, the Jeongmi (丁未) year of the Red Sheep.
Hidden stems
Each branch also contains one to three hidden stems (지장간). The Rat branch Ja, for example, holds Im and Gye Water; the Tiger branch In holds Mu Earth, Byeong Fire and Gap Wood. Hidden stems are why a chart with no visible Fire can still have some Fire inside it.
The five elements and the ten gods
Every stem and branch belongs to one of five elements: Wood, Fire, Earth, Metal and Water. They relate through two cycles. In the generating cycle Wood feeds Fire, Fire makes Earth (ash), Earth bears Metal, Metal carries Water (condensation) and Water nourishes Wood. In the controlling cycle Wood breaks Earth, Earth dams Water, Water quenches Fire, Fire melts Metal and Metal cuts Wood.
Compared with your day master, every other character takes one of ten roles called the ten gods (십성): Friend and Rob Wealth (same element), Eating God and Hurting Officer (the element you produce), Indirect and Direct Wealth (what you control), Seven Killings and Direct Officer (what controls you), and Indirect and Direct Resource (what produces you). A reader who says “you have strong Officer” is describing this relationship, not a job title.
The 12 life stages
A further layer, the 12 life stages (12운성), tracks how strong a stem feels in each branch, from Birth through Peak to Tomb and Conception, like the life of a plant through the year. On the day pillar pages you will find the stage of each day master on its own branch.
How a reading is built
- Convert the birth time. Korean practice uses Korea Standard Time history (including past daylight saving) and, often, a correction to local solar time.
- Write the eight characters using solar terms for the year and month, the 60-day count for the day and two-hour blocks for the hour.
- Weigh the elements, giving the month branch extra weight, to judge whether the day master is strong or weak.
- Name the ten gods and look for combinations and clashes between branches.
- Add timing: ten-year luck cycles (대운) and the yearly pillar (세운), such as 2027 Jeongmi.