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Standalone tool
Bazi Date Boundaries and Candidate Hours
Check Gregorian and lunar date boundaries and compare the Four Pillars for two possible birth hours on the same date.
Bazi helper
Check the boundaries before you chart
Enter a Gregorian date to compare it with 23:00 and 00:00 on either side, or pick two possible hours to see how the hour pillar changes on the same date.
Gregorian / lunar boundary cases
See how the date, lunar date and day pillar change around the boundary, using real conversions.
Choose a date to see the conversions at four boundary moments.
Rules: local civil time, the day changes at 00:00 (23:00–23:59 stays on the same day), and no true solar time correction.
Compare uncertain hours
Pick two possible hours to compare the calculated pillars on the same date. It does not guess your real birth time.
Choose a Gregorian date, then one or two possible hours, to see the Four Pillars here.
The comparison helps you organise what is uncertain. It does not say which hour is better and does not replace a birth certificate, family records or other evidence.
Continue with Bazi chart
Once the date and time are settled, go back to the Bazi chart for the full Four Pillars and a summary.