Why does birth time need correcting? ▾
Solar time, not clock time. In BaZi the hour pillar, and the day pillar near midnight, follow where the Sun actually was. Clock time is set for a whole time zone, so at your birthplace the Sun may cross the meridian earlier or later than clock noon. We use the longitude of your birthplace to correct for that, and can also add the equation of time (from −14 min in February to +16 min in November).
Daylight saving time is taken from your browser’s time zone database for the birth date, so summer-time births are converted to standard time automatically.
Whichever basis you pick, the “Pillars under each time basis” panel shows every combination side by side. If they differ, choose the one closest to the time on your birth certificate.