Calculator
True Solar Time BaZi Calculator
Your BaZi hour pillar can change when true solar time differs from clock time — so we never skip this step, and we never hide it.
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Cast Your Chart
The math appears as you type
Traditional chart calculations use this field as part of the calculation basis. It does not define the person’s identity.
Awaiting your birth details
HOUR BRANCH SHIFTED · CHOU → ZI — clock time and solar time fall in different branches; the corrected one is used.
What we compute for your birthplace
The historical timezone at your birth (including DST) · the longitude correction — minutes east or west of your timezone meridian · the equation of time — the sun’s seasonal drift · the resulting true solar time actually used for your hour pillar · a boundary-risk note when your birth sits near an hour or solar-term boundary.
If the recorded time is uncertain, start with birth-time correction. If the corrected time sits close to a branch change, inspect the exact hour-pillar boundaries.
If you want the concept and formula before using the tool, read what true solar time means and how the correction is calculated.
Questions
Frequently asked
Time measured by the sun's actual position at your birthplace — clock time adjusted for your longitude within the timezone and for the equation of time.
Commonly tens of minutes; at the edges of wide timezones it can exceed an hour — enough to shift an hour pillar.
Yes — historical DST rules for your birth date are applied from the IANA timezone database before the solar corrections.
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