True Solar Time Calculator
Enter your birthplace and birth time to calculate the true solar time step by step. The hour pillar in Bazi (八字) is based on true solar time, not the time on your watch.
Why the Difference?
- ⚠️ Daylight Saving Time (夏令時): Mainland China implemented DST from 1986–1991, and Taiwan also implemented it multiple times between 1945–1961. For people born during those periods, the time on their birth certificate is one hour ahead of standard time — most chart calculators don't handle this, causing the hour pillar to be offset by one full two-hour period (時辰).
- ⚠️ Longitude Difference (經度時差): A single time zone spans many longitudes. Urumqi and Beijing both use the UTC+8 zone, but the true noon differs by nearly two hours.
- ⚠️ Equation of Time (均時差): Because the Earth's orbit is elliptical and its axis is tilted, the sun does not cross the meridian at the exact same time every day. The difference can be up to ±16 minutes throughout the year, which is enough to change the hour pillar when crossing the boundary between two-hour periods.