BaZi without a birth time

Three of the four pillars do not need the time. Leave the Hour Pillar empty and read the rest.

What changes when the time is unknown

A BaZi (Saju) chart has four pillars: year, month, day, and hour. Without a time, only the Hour Pillar is missing. The Year and Month Pillars, the Day Pillar and its character, the Ten Gods and Twelve Life Stages measured from your Day Master, Void, and most Shen Sha come from the date alone. What you lose is the two characters of the Hour Pillar, the children and later-life seat they stand for, and two of the ten element counts.

Luck pillars barely change. Their starting age comes from the days between your birth moment and the nearest solar term, and with no time we use noon. Only births right next to a solar term can shift the starting age by about one year.

How to do it on this site

Turn on "I don't know the time" under the birthday. The chart is calculated at noon and the hour column is left blank. If a solar term falls on that day you get a "solar term boundary" note: the Month Pillar depends on the time of birth that day, so look at both possibilities.

If you might have been born between 11 PM and 1 AM, the Day Pillar can change too. See "The late Rat hour" below.

How to find your birth time

• Birth certificate: most countries record the time to the minute on the long-form certificate. Short-form or abstract certificates often omit it.
• Hospital records: the delivery record keeps the time, though retention periods vary and old records may be gone.
• Baby book or vaccination record: many have a line for the time of birth.
• Family memory: "around sunrise" or "after dinner" is enough to narrow it to one double-hour. Find that slot in the table below.

The 12 double-hours

BaZi divides the day into 12 slots of two hours each. The clock times below are for Seoul. Korea's standard time is set to 135° E, so the sun in Seoul runs about 32 minutes behind the clock, and every boundary shifts by 32 minutes. This site applies the same correction for whichever birthplace you choose: in New York the shift is about 4 minutes, in Tokyo about 19.

Daylight saving time in the birth year is handled automatically for every supported birthplace. Details are on the how we calculate page.

The late Rat hour

The Rat hour runs from 11 PM to 1 AM and straddles midnight, so there are two ways to read a birth between 11 PM and midnight.

• Late Rat hour (default): the day changes at midnight. Born at 11:30 PM, your Day Pillar is that day and your Hour Pillar is the Rat hour, with the hour stem taken from the next day's Day Master.
• Early Rat hour: the next day already begins at 11 PM. Born at 11:30 PM, your Day Pillar becomes the next day's.

Schools differ on which is right. This site uses the late Rat hour by default, and you can switch it under "Born around midnight?" in the form. Many people born between 11 PM and midnight look at both Day Pillars and keep the one that fits them better.

Born on a boundary

Within about 10 minutes of a boundary (the odd hours, at :32 on the Seoul clock) the Hour Pillar is uncertain, because recorded birth times are often off by a few minutes. The result shows an "hour boundary" note; read both Hour Pillars to be safe.

FAQ

Can I get a reading without a time at all?

Yes. The Day Pillar and character, this year's and next year's flow, luck pillars, and compatibility all come from the date. Only the children and later-life seat of the Hour Pillar stays blank.

Is a rough time good enough?

Yes. "Morning" or "around lunch" is a two-hour window, which is one slot. Find it in the table and enter the middle of the slot.

What if I was born outside Korea?

Choose your birthplace and the site applies that country's standard time, daylight saving history, and longitude offset. Do not convert to Korean time yourself.

The hour table applies the longitude correction. The two Rat-hour rules are a difference between schools, not a right and a wrong answer.