FAQ · Birth data and accuracy

Does the day change at 23:00 or at midnight?

The chart uses the late-zi convention: the day pillar turns over at 00:00, while the hour pillar turns over at 23:00, so the last two-hour block of the calendar day already belongs to the next hour pillar. Both turnover points are stated on the pages that show period windows, and the windows are aligned to them so that switching periods cannot silently mix conventions.

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