What is Saju?
Saju (사주, “four pillars”) — also called saju palja, the “eight characters” — turns your birth year, month, day and hour into four pairs of characters from the traditional East Asian calendar. Each pair has a heavenly stem on top and an earthly branch below, and each character belongs to one of five elements: Wood, Fire, Earth, Metal and Water. Chinese astrology calls the same system BaZi.
The most important character is the top of the day pillar, your Day Master — it stands for you. The rest of the chart describes how the five elements around you support or challenge it.
Why birthplace and “sundial time” matter
Saju uses the sun’s real position, not the time zone on your clock. Korea runs on UTC+9, but Seoul is at 127° east, so its solar noon arrives about 32 minutes later than clock noon. A birth at 11:10 by the clock in Seoul is really about 10:38 by the sun — which can change the hour pillar.
We convert your clock time to local solar time using your birthplace’s longitude, and you can switch on sundial time (true solar time), which also adds the equation of time — the up-to-16-minute drift through the year that a sundial shows. Daylight saving time and historical time zones are handled automatically.
Saju vs. Western astrology
- Western astrology uses the planets and 12 sun signs; Saju uses the solar calendar’s 24 seasonal terms and five elements.
- The Saju year starts at Ipchun (입춘, around February 4), and each month starts at a seasonal term — not on the 1st.
- Koreans use Saju for personality, compatibility between couples (gunghap, 궁합) and the year ahead (sinnyeon unse, 신년운세).
Saju in Korea today
Saju cafés in Hongdae, Gangnam and Ikseon-dong offer readings over coffee, and many Koreans check their fortune at New Year. Our numbers follow the same rules as Korean manseryeok (만세력) calendars used by professional readers.
Frequently asked questions
Is Saju the same as Chinese BaZi?
It is the same four-pillar system. Korean readers use it with Korean terms and traditions, and often emphasize compatibility (gunghap) and yearly fortune.
Why do you ask for my birthplace?
To convert your clock time to local solar time. The hour pillar changes every two hours of solar time, so a 30-minute difference can matter.
What if I don’t know my birth time?
Tick “I don’t know my birth time”. You get three pillars (six characters), which still show your Day Master and most of your elements.
Why is my Saju animal different from my Chinese zodiac?
Saju changes the year at Ipchun (about February 4). Many Chinese zodiac charts use Lunar New Year instead, so January and early-February births can differ.
Sources: lunar-javascript (6tail, MIT) — solar terms and pillars. Last checked: 2026-10-09