Why do BaZi calculators give different results?
A checklist for comparing time zones, solar terms, true solar time, late-Zi conventions and element-count methods.
Compare the inputs before the readings
Use the same Gregorian date, recorded local time, birthplace and time zone. Check whether daylight saving time was in effect on the birth date. A current UTC offset is not necessarily the historical offset, and a city name alone is not a complete calculation record.
Check the term boundary
A date-only approximation can switch a month at midnight when the actual solar term occurs in the afternoon. GuanXing evaluates the absolute birth instant against the library’s solar-term boundaries. That is different from assuming every February 4 birth belongs to the new year.
Write down the midnight convention
Some calculations change the day at 23:00. Others change at midnight, but still derive the late-Zi hour stem from the next day. A third approach retains the current day for both. GuanXing exposes these choices so a difference can be reproduced rather than hidden.
Separate precision from interpretation
Matching four pillars does not require two tools to show identical element percentages: one may count visible characters, another may weight hidden stems or seasons. Our methodology page separates tested calendar behavior from approximations and cultural interpretations.
Calculation references
- Hong Kong Observatory: stems and branches ↗
- Hong Kong Observatory: 24 solar terms ↗
- lunar-javascript calendar engine ↗