Free BaZi Calculator: Time Zone, DST and True Solar Time Handled Automatically

How the calculation works

  1. Use the birthplace's time zone rules to turn the clock time into an exact instant. Whether daylight saving applied there on that date comes from the time zone database, including historical changes (such as mainland China's DST in 1986–1991).
  2. True Solar Time = the exact instant + the birthplace's longitude × 4 minutes + the equation of time for that day.
  3. The year and month pillars come from the sun's ecliptic longitude: the year changes at Li Chun, and each month spans 30° from Li Chun.
  4. The day and hour pillars follow True Solar Time: the day changes at 23:00 (Zi-start) and the hour pillar is one of twelve two-hour periods.
  5. The stem of the day pillar is your Day Master, which stands for you; then the five elements of the eight characters (four stems and four branches) are counted.

Limits to know

  • The more exact the birth time, the more reliable the result. Near an hour boundary, a few minutes can change the hour pillar.
  • Time zone records for early births are not always complete (for example, local times varied across China in the Republican era); where that matters, trust family recollection or records.
  • This page casts the four pillars, Day Master and element balance only; it makes no readings. For how BaZi is read, see What Is BaZi?.
  • A second school, "the night Zi hour does not change the day," changes the day at 00:00, so people born 23:00–24:00 get a different day pillar under it; this page uses the mainstream 23:00 change.

Born Overseas: Finding Your Correct BaZi Hour · True Solar Time Explained · What Is My Chinese Element?

FAQ

I was born abroad. Do I convert to Beijing time first?

No. BaZi follows the sun over the birthplace, so use the local time at the birthplace and let the calculator handle the time zone, daylight saving and True Solar Time.

Daylight saving was in effect where I was born. What do I do?

Enter the local clock time from the birth certificate. The calculator checks the rules for that place and year and removes daylight saving for you.

Can I cast BaZi without knowing the birth hour?

You can estimate a time to get the year, month and day pillars; the Day Master and day pillar do not depend on the hour. The hour pillar needs an accurate birth time.