Chinese cultural term · reviewed 2026-10-21
子时
Zi hour
zǐ shí · the Zi time period
The two-hour period around midnight, from 23:00 to 01:00.
A familiar bridge
Start from something known.
A two-hour night window spanning midnight, with schools disagreeing about the exact day-change point.
Worked example
See the term in position.
Under a 23:00 late-Zi convention, a 23:30 birth is assigned to the following day position; under civil midnight it is not.
Cultural context
What surrounds the word.
Traditions differ over whether the day pillar changes at 23:00 or at civil midnight. The difference matters for births inside this interval.
Boundary
What it does not mean.
There is no single globally undisputed rule; the convention must be stated.
Inside the portrait
How this term appears here.
The selected 23:00 or civil-midnight setting can change the day and hour positions, so boundary variants are shown separately.