BAZI KNOWLEDGE BASE

Beijing time or solar time: which birth time belongs in BaZi?

Beijing time is China’s civil time standard, normally expressed as UTC+8. It is different from the local solar time of a birthplace. For a BaZi chart, start with the time actually recorded at birth, then check which conversions the service performs.

Clarify · Updated 2026-09-04

What time should I enter?

Use the birth date and clock time recorded at the birthplace, along with that location, unless the service explicitly asks for an already converted time. Keep the original record unchanged so that any conversion can be checked.

A birth recorded outside China is not automatically a Beijing-time birth. Converting it to Beijing time yourself can change the calendar date, and a service may then apply another time-zone conversion. The input instructions should make clear whether they expect local clock time or a converted value.

Clock time, mean solar time and apparent solar time

Clock time follows civil rules for a location and date. Mean solar time is based on longitude and an idealized uniform Sun. Apparent solar time follows the Sun’s apparent motion, which differs from that average during the year.

Time standard	What it depends on
Civil or clock time	The location, date and historical time-zone rules
Local mean solar time	A confirmed time basis and the location’s longitude
Local apparent solar time	Mean solar time and the date’s equation of time

Why does the birthplace matter?

Places sharing the same civil time zone can have different longitudes. When a method uses solar time, an eastern and a western location therefore need different corrections even if both clocks display the same time.

Historical clock rules matter separately. Daylight-saving time and changes to time-zone policy can affect a birth record. IANA’s Time Zone Database records these historical rules; the current UTC offset alone is not enough for every birth date.

Can a small difference change the chart?

It can matter near a boundary used by the chosen method, such as the division between two two-hour periods, the start of a day or a solar-term (one of 24 seasonal markers defined by the Sun’s position along its yearly path) boundary. A large-looking time correction does not necessarily change a pillar, while a small one can matter for a time very close to a boundary.

For a simplified longitude example, a location at 116.4° east lies 3.6° west of the 120° reference meridian for UTC+8. At four minutes per degree, the mean-solar correction is minus 14 minutes 24 seconds, assuming the clock basis has already been confirmed and no daylight-saving correction is needed. A clock reading of 11:05 would become 10:50:36 mean solar time. Apparent solar time still needs the date-dependent equation of time.

Why do two BaZi services give different results?

Compare the original input, birthplace, historical time-zone treatment, solar-time option and day-boundary convention. One service may show the recorded clock time while another displays a corrected time. The labels can differ even before the interpretation begins.

Avoid adjusting the time manually and then enabling an automatic correction for the same effect. A useful service should explain its input and conversion rules so that you can see how the displayed chart was obtained.

What if I only know an approximate time?

Keep the uncertainty visible. “Around 11” contains less information than a record stating 11:05. If the plausible range crosses a relevant boundary, compare the possible charts and identify which parts change.

A meaningful review should preserve what is known and distinguish it from assumptions. Choosing whichever chart feels most flattering does not resolve the uncertainty in the birth record.