Korean Saju Calculator
Koreans don’t ask your star sign. They ask your birth hour.
Korean saju is built from four pillars: your year, month, day and hour. The upper character of the day pillar is your Day Master, the character that stands for you — where a sun sign is one of twelve, a Day Master is one of ten. Enter your birth details and see all eight characters, free.
Already got a saju reading from ChatGPT? Run it here too. If the two disagree, it is almost always the birth hour — see how this is calculated.
The ten Day Masters
Find the character your result gave you
Your Day Master is one of these ten. Open yours for the way it tends to work, love and make decisions — including when that same strength gets in your way.
How this is calculated
A chart is arithmetic before it is interpretation
Solar-term month boundaries
The month pillar changes with the sun's position along the ecliptic (the solar terms), not the calendar month. The exact crossing moment is applied, so the month never flips a day early or late.
True solar time
Your birth moment is converted to the local time actually in force at your birthplace on that date, then corrected toward true solar time using your city's longitude.
The midnight boundary
Births between 11 pm and 1 am sit on the boundary where the day turns over. The calculator resolves which day pillar applies automatically — a birth near midnight can land on a different pillar entirely.
Historical daylight saving
If summer time was in force where and when you were born — including daylight-saving periods that no longer exist — your birth is converted back to standard time first. Many calculators skip this step.
Anywhere on Earth
Wherever you were born, the same correction runs on your birth city's IANA time zone — we apply the historical time zone and daylight saving rules for that exact date.
Frequently Asked Questions
What is a Day Master?
Your Day Master is the character that stands for you in your own chart — the upper character of your day pillar. Where a sun sign is one of twelve, a Day Master is one of ten, and it is drawn from the day you were born rather than the month.
Why do you need my birth hour?
One of the four pillars is built from the hour. It is the same reason your rising sign needs an exact birth time in Western astrology. You can still get three pillars and your Day Master without it.
Why does my chart differ from another site's?
Usually the birth hour. A chart has to be built in the local time actually in force where and when you were born, including historical daylight saving. Many calculators apply today's rules, or skip the correction entirely, which can shift the hour pillar by one position.
Is this the same as Chinese BaZi?
The eight characters are the same tradition of the Four Pillars. Saju is the Korean lineage of it, with its own interpretive conventions. Neither is a translation of the other.
Is the calculator really free?
Yes. There is no account, no email and no payment. The paid reading is the interpretation — what your chart means, your ten-year cycles and the year ahead.
Go deeper into Korean Saju
For entertainment and self-reflection — not medical, legal or financial advice.