Four Pillars (Saju / BaZi) Calculator

Calculates the eight characters of your Four Pillars (BaZi) from your birth date and time, with the five elements, ten gods, hidden stems, 12 stages and luck cycles.

How to use

1. Under "Calendar", choose "Solar (Gregorian)" or "Korean lunar" and enter the date of birth.
2. Enter the "Time of birth" or tick "I don't know the time", and choose the gender, which sets the luck cycle direction.
3. Choose the "Place of birth" and "Time zone". Switch on "Use the late Rat hour (yaja-si)" if you follow that rule.
4. Read the chart and the reading below it. Use "Save as image", "Copy as text" or "Copy share link" to keep it.

How it works

• The year pillar changes at the Start of Spring and the month pillar at the 12 major solar terms. The Sun's position is computed with Meeus's method (VSOP87) and matches the Hong Kong Observatory's solar-term times for 2019–2028 within a minute.
• Solar years 1900–2100 and lunar years 1900–2050 are supported, with the standard time and daylight saving of the period.
• The share link contains the birth date, time and gender. This is a for-fun reading based on traditional saju calculation; results differ between schools.

Questions and answers

Can I get my BaZi chart without a birth time?

Yes. The hour pillar is shown as "Unknown" and the other six characters are calculated.

Which year pillar do I have if I was born in January or early February?

The chart year changes at the Start of Spring, around 4 February, not on 1 January or at Lunar New Year. Born before it, you have the previous year's pillar and animal.

What is the late Rat hour (yaja-si)?

A rule for births between 23:00 and 24:00. When it is on, the day pillar stays on that day and only the hour pillar moves to the next day. When it is off, the day changes at 23:00.

How is the starting age of the luck cycles calculated?

The days from birth to the next or previous solar term are divided by 3, so 3 days count as 1 year. Each later cycle starts 10 years after the one before.