Calendar and charting time
Charting usually needs birth date, time, and (depending on the system) place.
Common points
- Solar ↔ lunar: systems such as Zi Wei often enter the chart with lunar month, day, and double-hour; BaZi month pillars more often follow solar-term boundaries than pure lunar month starts.
- Solar terms: changing the month pillar at the jie (not the zhong qi) is a mainstream BaZi convention.
- Double-hours: the twelve double-hours map to Earthly Branches; day-change at Zi hour has its own entry.
- True solar time: some schools correct clock time by longitude; whether a product enables this by default follows the engine’s rules.
A one-hour error can shift all four pillars and palace placements, so time precision outranks over-reading a single character.