Usage guide · BaziSphere
How to fill in birth time: timezones and true solar time correction
Born across timezones, far from the standard meridian, or near an hour boundary? Here is how to verify your input before charting.
The most overlooked detail is where the clock time belongs
When charting, the easiest thing to miss is not a term but which place the 'clock time' belongs to. A birth certificate records the local time in use at that place and moment; before typing it into a website, confirming the birthplace, date and how the time was recorded is more reliable than comparing interpretations afterwards.
Enter the original local time first
If the birth certificate says 14:30 on a certain day, record that time faithfully, together with the timezone in effect at the birthplace then. This site's date fields take the Gregorian calendar; if the record is lunar, convert it to the matching Gregorian date first. Do not convert to Beijing time yourself and then also select the birthplace timezone on the page — that would double-convert. The site offers UTC offset options so local times from different regions can be brought to one calculation baseline; if daylight saving time was in effect locally, include it in the offset, because the system does not infer it automatically.
If you only know 'afternoon' but not the exact minute, acknowledge the uncertainty; near an hour boundary, a few minutes can change the hour pillar. Do not treat a vague birth time as a precise record just to get a result you prefer.
What longitude and true solar time correction are
A standard timezone covers a range of geography, and the sun's position is not perfectly synchronized across longitudes within it. This site's optional longitude correction is called 'true solar time adjustment': the local time is first converted to Beijing time, then adjusted by about 4 minutes per degree of difference from 120°E. This is a longitude-based conversion; it does not additionally apply the 'equation of time' caused by the sun's varying speed. Confirm the longitude of the birthplace before entering it — do not guess from memory.
Whether to apply the correction matters most for births close to an hour boundary. Keep the original birth record, and note down both the raw clock time and which correction produced a given chart, so later comparisons stay traceable. Different schools may handle time differently; what matters is stating clearly which rule you used.
A practical checklist
Charting computes the result for the input you give, but it cannot recover a missing birth record. Once your information is complete, create a chart from the home page and check that the Four Pillars match the input; if you want to start from the basic sections, continue with the beginner's reading order.
- Check the birth certificate or family records: the date, the hour and minute, and whether the calendar was Gregorian or lunar.
- Confirm the timezone in effect at the birthplace at that time; for births abroad, do not simply apply China Standard Time.
- If you use true solar time correction, verify the longitude and remember whether the correction was applied.
- If the birth was near 23:00 or a solar-term transition, double-check the exact moment and the day-change rule in use.
- Keep a note of the input conventions, so the same facts are used when reading reports or comparing other tools.