Free Korean Saju calculator
Your Korean birth chart (Four Pillars), computed from your exact birth moment — no questionnaire, nothing to fill in. A mirror for self-reflection, not a prediction.
Pick your birth city — timezone & historical daylight-saving are handled automatically.
What do these mean? → · Why ChatGPT gets this wrong →
Frequently asked questions
Is this really free? Do I need to sign up?
Yes — it computes instantly, no sign-up. Enter your birth date, time, and place, and you get your Saju (Four Pillars) chart, Day Master, Five Elements, and day pillar right away.
How accurate is this calculation?
We derive solar-term timing through astronomical calculation (VSOP87 solar longitude, ΔT correction), matching KASI's (Korea Astronomy and Space Science Institute) published values within ±1-2 minutes, and we correct for true solar time based on your birth longitude. The same birth date and time always produces the same chart (deterministic).
I got a different result from another Saju app.
That can happen because of differing conventions around the late-night hour boundary (11pm-midnight), historical daylight saving time (1948-51, 1955-60, 1987-88 in Korea), or true solar time. Gwiraedang shows you exactly which corrections were applied, right on the result screen.
What's the difference between the calculator and the chat app?
The calculator only shows you the chart — the facts. From there, you can talk it through with one of Gwiraedang's five AI counselors, each with their own voice, in the app (free to try, no login required).