True solar time calculator

See the exact clock-time correction used before a BaZi chart is cast.

Historical timezone and daylight-saving rules are resolved for the birth date.

This calculation is not saved to an account or database.

How the correction is calculated

Clock standard

The recorded local time is matched to the IANA timezone and UTC offset in force on that date, including historical daylight saving time.

Solar position

The calculation combines the longitude difference from the timezone meridian with the equation of time for that day of the year.

Different schools use different conventions

Some BaZi practitioners use recorded clock time, while others apply true solar time. The useful standard is a method that states its convention and lets you inspect the correction.