The Four Pillars
Saju is four pillars — the year, month, day and hour of your birth, each written as one heavenly stem over one earthly branch: eight characters in all (which is why it's also called 'eight characters,' 八字, or BaZi). Each pillar speaks to a different part of life, and they're all read against your Day Master.
What a pillar is
Each pillar is two characters: a heavenly stem on top and an earthly branch below. There are ten stems and twelve branches — the branches are the same twelve zodiac animals. Four pillars × two characters = eight characters, your 팔자 (八字).
What each pillar covers
| Pillar | Speaks to |
|---|---|
| Year 년주 · 年柱 | Ancestry, early life, the wider world — and the zodiac animal everyone knows you by. |
| Month 월주 · 月柱 | Parents, upbringing and career. It sets your birth season, so it carries the most weight when judging how strong each element is. |
| Day 일주 · 日柱 | You. The top character is your Day Master — the one that represents you — and the branch beneath it speaks to your closest partner. |
| Hour 시주 · 時柱 | Children, later life and your private inner world. This is the pillar that needs your birth time. |
Why the hour pillar needs your birth time
The hour pillar is set from true solar timeat your birthplace — the sun's real position, which can differ from the clock by tens of minutes. That's why an accurate engine computes it rather than guessing. Without a birth time you still get three solid pillars; Gwiraedang leaves the hour blank rather than inventing one.
How four pillars become a reading
The Day Master — the day's stem — is the anchor. The other seven characters are read as relationships to it (the Ten Gods), across the Five Elements, and then the ten-year luck cycles (대운) and the yearly cycle (세운) move the whole chart through time. So your eight fixed characters are the material; the cycles are the timing.
Is Saju the same as BaZi?
Essentially yes — it's the same four-pillar, eight-character method. 'Saju' (사주) is the Korean name and 'BaZi' (八字) is the Chinese one. The structure is identical; some interpretive details differ between schools and traditions.
Which pillar is the most important?
The Day pillar, because its top character is your Day Master — you. For judging how strong each element is, though, the Month pillar matters most, since it fixes the season you were born into.
What if I don't know my birth time?
You still get the year, month and day pillars — three of the four — which is plenty for a meaningful reading. Only the hour pillar needs your time, and Gwiraedang leaves it blank rather than inventing one.
See your four pillars
Eight characters, computed accurately from your birth date, time and city. Free.
Read my Saju