Start with the recorded local time
Use the local clock time on the birth record, with the time zone for the birthplace. A time zone selected for where you live now may be wrong for where you were born.
Our selector uses IANA zone names such as America/New_York and Asia/Shanghai. These include historical changes, unlike a single current UTC offset. A city name alone does not reliably identify a time zone.
Daylight saving creates real ambiguity
When clocks move forward, some local times do not exist. When clocks move back, an hour may occur twice. Our form rejects these special cases rather than choosing an instant without telling you.
If your recorded time falls in a repeated hour, verify the historical offset with the record or a reliable time-zone reference. You can use a fixed-offset zone only when you know which offset applies.
Civil time and true solar time
Civil time follows legal time-zone rules. Local mean solar time relates to longitude; apparent solar time also includes the equation of time. Some BaZi schools adjust to solar time, while others use recorded clock time.
Our launch version uses civil time and states that choice. It does not infer longitude, calculate a solar correction or claim identical results across different schools.
If you do not know the birth time
Do not substitute noon and then treat the resulting hour pillar as known. A guessed time can also affect the day near midnight or the year/month near a solar-term boundary.
You can still explore the Atlas without a chart. If trying an approximate time for curiosity, treat the output as a scenario and compare how it changes; it is not a recovered birth time.
Find the story in your own chart.
Calculate your four pillars, meet your Day Master and take away a signature card.
Reveal my signatureCalendar reference: Hong Kong Observatory: the 24 solar terms. Calculation engine: lunar calendar documentation. Archetype labels, exercises and artwork are modern editorial interpretations. Read our method.