BAZI KNOWLEDGE BASE
Does Zi hour belong to today or tomorrow? 23:00, midnight and late Zi
Zi hour spans midnight, usually written as 23:00–00:59. Having Zi as the Hour Branch therefore does not settle which day supplies the Day Pillar. Conventions can change the day at 23:00, wait until midnight, or retain the day while deriving the hour from the following Day Stem. Ask separately about the day, the hour stem and the time scale.
An hour interval and a day boundary are separate rules
Zi’s first hour lies before civil midnight and its second after it. The calendar date and the start of Zi are therefore different questions. Saying only “the day changes at Zi” still leaves 23:00 versus 00:00 unresolved.
Some methods derive late Zi’s stem from the following day without changing the displayed Day Pillar. A Jia day paired with Bing Zi need not be an accidental application of Five Rats; first establish whether this split convention was intended.
How three conventions treat the same 23:30
Suppose the chosen time scale reads 23:30, the current date is Jia Zi and the next date Yi Chou, with no further time correction. This compares only day and hour calculations, not which interpretation suits a person better.
| Convention | Displayed day | Hour |
|---|---|---|
| Move to the next day at 23:00 | Yi Chou | Bing Zi |
| Wait for midnight; use current stem in late Zi | Jia Zi | Jia Zi |
| Retain current day; derive late Zi from next stem | Jia Zi | Bing Zi |
Which clock reads 23:30?
A certificate reading 23:30 might become 22:50 after solar-time correction, changing even the Hour Branch from Zi to Hai. That difference concerns the time scale, not just the rollover school. Fix time-zone and solar-time treatment before comparing day boundaries.
If correction crosses midnight, solar and civil dates can differ. A report needs to state which date supplies the Day Pillar and which stem derives the hour. The phrase “uses true solar time” does not explain all of those dependencies.
What Clarify currently does
Clarify currently retains the entered civil date for the Day Pillar. With a known time and valid birthplace, it uses the corrected clock for the Hour Branch. If that clock’s hour is 23, it derives the hour stem from the day after the entered date. In the uncorrected example above, this corresponds to the third row.
There is currently no user-facing switch between two day-boundary modes, and a solar-date rollover does not recalculate the Day Pillar. Outside the 23:00 hour, even after a solar-date change, the hour stem remains based on the entered date’s stem. An older claim of a default 23:00 day rollover with selectable dual charts does not describe current behavior.
Ask a question that identifies the disagreement
Compare the birth record, corrected clock, displayed Day Pillar and stem used for the hour. You can then ask, “Why does your Jia Zi day have a Bing Zi hour?” rather than only asking which chart is right.
Separate the recorded facts from conventions and retain candidates that actually differ. Personal experience can inform how you understand an interpretation, but liking a description does not establish the birth time or prove a rollover rule.