Hour Boundary
How to Chart Early and Late Zi Hour
Zi hour straddles midnight: 11 p.m. to 1 a.m. is one branch. The fight is not the hour name. It is whether the Day Pillar stays today or moves to tomorrow.
TianJiGe Editorial TeamUpdated
TianJiGe changes the day at 23:00. From 23:00 to 00:59 the Hour Pillar is next-day Zi, and the Day Pillar uses the next civil day. Do not keep the clock date, and do not pick a school because the chart sounds nicer.
Why Zi hour splits into early and late
The earthly branch Zi covers two hours: 23:00 to 01:00. Civil calendars flip at midnight, so the same branch is cut in two. 23:00–00:00 is often called late Zi; 00:00–01:00 is early Zi.
Both halves are still Zi. The argument is the Day Pillar. Zi is the first of the twelve hours, so traditional charting often starts the new day at 23:00, not at midnight.
A birth at 11:20 p.m. can still show today's date on the household register, while the chart already uses tomorrow's day stem. Change the Day Master and the Ten Gods, structure, and luck-cycle start all move.
Where the two schools differ: 23:00 or midnight
Most Zi Ping practice changes the day at 23:00. Late Zi and early Zi then share the next day's Day Pillar, with Hour Pillar Zi in both cases.
Example: clock time 12 May 2024, 23:20. With a 23:00 change, the Day Pillar is 13 May and the hour is Zi. With a midnight change, the Day Pillar stays 12 May and the hour is still Zi. The Day Master can be a different stem.
At 00:20 on 13 May both methods usually agree: 13 May, Zi hour. Almost all real disputes sit in that one hour between 23:00 and midnight.
Another school splits Zi: Zi-chu (23:00–00:00) keeps today's Day Pillar but uses the next day's hour stem; Zi-zheng (00:00–01:00) moves both. TianJiGe does not use that split, so one clock time does not produce two Day Pillars.
How to enter it, and what to check near 23:00
Enter the hospital or clock time, minutes if you have them. The engine treats 23:00 as the day line: 23:00–00:59 is next-day Zi, and the Day Pillar follows.
If true solar time is on, check the corrected clock against 23:00. Chengdu 23:20 minus about 64 minutes is 22:16, back in Hai of the same day. Shanghai 23:20 usually stays in next-day Zi.
A certificate that says 23:00 sharp is a boundary. After charting, look at the day stem. If it is not the birthday you remember, check the 23:00 rule and solar time before you edit the hour.
If the minute is unknown, chart two versions
If you only remember 'near midnight', chart 22:40 (Hai, same day) and 23:20 (Zi, next day). Shared conclusions are steadier; a different Day Master stays pending.
Correct against lived events: school, a move, surgery, marriage, a job start. Keep the chart that explains the life, not the nicer one.
With no record, use a three-pillar sketch and mark both the hour and the day line as pending. This is a date-boundary problem, not a luck switch.
How to Get Started
- 1Find the civil clock time, to the minute if possible.
- 2Treat 23:00–00:59 as next-day Zi; do not write back today's date.
- 3With a birth city, turn on true solar time and see if 23:00 was crossed.
- 4After charting, check whether the day stem already moved.
- 5If the minute is fuzzy, compare same-day Hai with next-day Zi.
- 6Correct with real events, not with which Day Pillar looks luckier.
Common Mistakes
- Keeping 23:00 as same-day Hai or same-day Day Pillar.
- Switching to midnight change or a Zi-chu split to improve the Day Master.
- Ignoring true solar time, especially for western births near 23:00.
- Remembering only 'Zi hour' without separating 23:00 from after midnight.
- Keeping the old reading after the Day Pillar has changed.
Try the Tool
Ba Zi — Four Pillars
Chart Ba Zi with solar or lunar dates and optional true solar time — Four Pillars, Five Elements, Ten Gods, and Major Luck Cycles, plus AI analysis on demand.
FAQ
TianJiGe changes the day at 23:00: 23:00–00:00 uses the next Day Pillar with Hour Pillar Zi. The civil date on paper can still be today.
Under a 23:00 change, 23:20 and 00:20 the next morning often share the same Day Pillar and Zi hour. A midnight change splits those two.
Related Reading
Online chart
Uncertain Birth Hour
Should you use true solar time?
How to Calculate Ba Zi
Ba Zi — Four Pillars
Chart Ba Zi with solar or lunar dates and optional true solar time — Four Pillars, Five Elements, Ten Gods, and Major Luck Cycles, plus AI analysis on demand.
Zi Wei Dou Shu
Generate your Zi Wei chart — twelve life palaces, star placements, and an AI interpretation of your destiny blueprint.
Auspicious Date Picker
Browse the Chinese almanac — find the best dates for moving, weddings, business openings, and more.