LEARN · BAZI
Does Bazi Need True Solar Time?
Some Bazi calculators correct your birth time to true solar time, and others use the clock time on your birth certificate. Schools differ, and neither choice is simply right or wrong. This page explains the difference and when it matters.
Clock time and true solar time
- Clock time is the time on your birth record, in the time zone of your birth place.
- True solar time adjusts that clock time for the longitude of the birth place and for a small seasonal correction (the equation of time).
The two can differ by minutes or more than half an hour, depending on the place and the date.
What schools do
Practitioners disagree. Some convert to true solar time before building the chart. Others build the chart from the clock time and use the solar correction only as a reference. In the school we follow, the chart uses the local clock time at birth, and true solar time is treated as a reference when the birth time is very close to an hour boundary. The free Bazi calculator on this site uses the clock time you enter, and says so on the page.
When it actually matters
| Your birth time | Does the choice change the hour pillar? |
|---|---|
| Comfortably inside a two-hour block | Usually not |
| Within a few minutes of a block boundary | It can |
| Close to 23:00 or midnight | It can change the day pillar too |
If your time sits near a boundary, note the exact time and the birth city, and ask a reader to check how much the reading depends on it.
How to check your own chart
- Find the time on your birth record and the birth city.
- Run the chart on more than one calculator and compare the four pillars.
- If the hour pillar differs, see whether you fall in the boundary cases above.
- Bring both versions to a reader. See why Bazi calculators give different results.
FAQ
Frequently asked questions
Does Bazi use true solar time?
Schools differ. In the school we follow, the chart uses the local clock time at birth, and true solar time is a reference for borderline times.
Is a calculator with true solar time more accurate?
Not necessarily. It follows a different convention, and for most birth times the pillars are the same.
Does birthplace affect a Bazi chart?
It affects the time zone and, if you use true solar time, the longitude correction.
What should I do if my birth time is close to a boundary?
Write down the exact time and the city, and ask a reader how much the reading depends on it.
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