One birth minute — but different apps give you different charts. They follow different calendar schools. Compare four of them side by side: which pillar changes, and why. No fortune-telling — just the math.
Two schools, same minute: the day pillar flips because they draw the day boundary at different hours.
Four schools, side by side
① Almanacday flips at midnight solar terms by day
② Early-Ziday flips at 23:00 solar terms by day
③ Solar-term instantday flips at midnight terms at the exact moment
④ True solar③ + longitude correction
Year
Month
Day
Hour
Why they differ here:
Six classic split points exist between schools. See all six →
Year start — Li Chun vs Lunar New Year
Month pillar — flips on the solar-term day vs at the exact moment
Late Zi hour (23:00–24:00) — does the day flip at 23:00 or midnight
True solar time — vs clock time
Daylight-saving clock times — China 1986–91; the US still observes DST
Luck-pillar start age & direction
This tool shows the pillar impact of 1–4. Classes 5–6 belong to the detailed report. Even open-source calendar maintainers refuse to arbitrate class 3 — it is lineage, not error.
Detailed report · in preparation
Which splits hit your chart?
The comparison above is free and complete. The paid report goes deeper on your specific birth:
Your exact risk classes among the six split points
Luck-pillar start-age math (early vs late Zi)
Minute-level boundary analysis for your true-solar correction
A one-page checklist for your practitioner
Daylight-saving verification — shipping with the report, not before it works
$4.9 one-time at launch · no subscription
Added. You'll get one email when the report launches — nothing else.