What this Bazi calculator does
Bazi (八字, “eight characters”), also called the Four Pillars of Destiny, describes a moment of birth with four pairs of Chinese calendar signs: one pair each for the year, the month, the day and the two-hour period of birth. Each pair is a heavenly stem on top of an earthly branch, so the chart has eight characters in total. This calculator works out those eight characters, the stems hidden inside each branch, the “ten god” relationship of every stem to your Day Master, a simple count of the five elements, and the ten-year luck pillars (大运) with the age at which they begin.
Most of the work in a correct chart is getting the time right, so we show it step by step. Bazi uses the solar calendar of the twenty-four solar terms, not the lunar month and not 1 January. The year pillar changes at the exact moment of 立春 (Start of Spring, around 4 February) and the month pillar changes at each of the twelve “jie” solar terms. The day and hour pillars depend on the local position of the Sun, so we convert your clock time to true solar time using your birthplace’s longitude and the equation of time, after first applying the time-zone and daylight-saving rules that were in force on that date.
How to use it
- Date and time: enter the time shown on the birth certificate, in the local time of the birthplace. If you do not know it, tick the box and we will leave the hour pillar blank.
- Birthplace: type the first letters of the city and pick it from the list. The list contains about 34,000 places with a population over 15,000, from GeoNames. If your town is missing, choose the nearest city, or open “Options” and type the longitude and IANA time zone yourself.
- Gender: in classical practice it only decides whether the luck pillars run forward or backward through the calendar.
- Options: you can switch off true solar time to use the clock time as many printed almanacs do, and choose how births between 23:00 and midnight are handled. Both conventions are explained on our method page.
Why charts differ between websites
If another site gives you a different chart, the reason is almost always one of four conventions: whether true solar time is used; how the hour from 23:00 to midnight is assigned; whether historical daylight-saving time was applied (China used it from 1986 to 1991, for example); and whether the year starts at 立春 or at the Lunar New Year. We follow the mainstream classical rules — year from 立春, months from the solar terms, day and hour from local solar time — and tell you on the result when your birth falls close enough to a boundary that a small error in the recorded time could change a pillar.
How accurate is it?
The calendar engine is the open-source lunar-javascript library. On top of it we added our own time-zone, true-solar-time and boundary handling, and we test the whole pipeline against outside data: the solar-term dates published by the Hong Kong Observatory for every year from 1901 to 2100, the 2025 solar-term times to the minute, a day-pillar formula derived independently from the Julian day number, and 35 published charts of historical figures. The current results and every mismatch are listed on the method page.
Start learning
Bazi is a traditional Chinese cultural practice. This site presents it for study and entertainment. It does not predict the future and is not medical, financial, legal or psychological advice. See our disclaimer.