True Solar Time Calculator
Enter place and time of birth to calculate True Solar Time step by step. The hour pillar in Bazi is based on True Solar Time, not your watch time.
Why would there be a difference?
- ⚠️ Daylight Saving Time: Mainland China observed DST from 1986–1991, and Taiwan did so 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 charting tools don't account for this, causing the hour pillar (時柱) to be off by an entire two-hour period (時辰).
- ⚠️ Longitude Time Difference: A single time zone spans many degrees of longitude. Ürümqi and Beijing both use UTC+8, but their true solar noons differ by nearly two hours.
- ⚠️ Equation of Time: The Earth's orbit is elliptical and its axis is tilted, so the sun doesn't cross the meridian at the same time each day. The difference can be up to ±16 minutes throughout the year, which is enough to change the hour pillar when crossing a two-hour period boundary.