How to Find Your Birth Time: Records First, Then Narrow It Down
There are many ways people claim to work out a birth hour, but a record always beats them. This page goes in order of reliability: records first, then family memory, and only last working backward from the chart. The further down the list, the more the answer can only be "more likely."
Step one: look for records
| Source | Notes |
|---|---|
| Birth certificate | Issued by the hospital, midwife or registrar, and in many places recorded to the minute. If the family kept the original or a copy, this is the most accurate source. |
| Child health records | In Taiwan, the Children's Health Handbook of some years has a birth details section; in other countries, a baby book or early medical record may note the time. |
| The hospital you were born in | Retention rules vary. In Taiwan, the Medical Care Act generally requires records to be kept at least seven years, and for minors until seven years after they come of age. Old records are usually gone, but if you were born in the last twenty or thirty years it is worth asking. |
| Family papers | Diaries, the backs of photos, birth announcements, or in Chinese families the red paper that announced a birth sometimes note the time. |
| People who were there | Your mother, grandparents or relatives who helped. Even if they cannot recall the hour, they often remember whether it was light yet or whether they had eaten. |
Civil birth registration often records only the date, not the time. If the time you find falls in a daylight-saving period, remember to take off the extra hour first.
Step two: narrow it down from what family remember
| What family often say | Likely two-hour periods |
|---|---|
| In the middle of the night, just after midnight | Early Zi (00–01), Chou (01–03) |
| Before dawn, when the roosters crowed | Yin (03–05), Mao (05–07) |
| Early morning, around breakfast | Mao (05–07), Chen (07–09) |
| In the morning | Chen (07–09), Si (09–11) |
| Around noon, near lunchtime | Wu (11–13) |
| In the afternoon | Wei (13–15), Shen (15–17) |
| Early evening, as it was getting dark | You (17–19) |
| In the evening, after dinner | Xu (19–21), Hai (21–23) |
| Very late, nearly midnight | Hai (21–23), Late Zi (23–24, day pillar moves to the next day) |
A remembered time of day usually narrows things to two or three periods. Then use the twelve-hour tool and look only at those rows: if they agree on strength and the useful god, there is no need to go further.
Step three: check against past events (rectification)
Cast each of the remaining hours and test them against a few major events from your past: moves, changing schools, marriage, job changes, losses in the family. See which chart's annual pillars (clashing or combining with the hour pillar) or luck pillar changes line up better with those years.
- There are fewer clues than you might think: except on solar term days, the sequence of luck pillars does not change with the hour; the hour only changes the hour pillar and the starting age. So rectification comes down to two things: the years the luck pillars change, and annual pillars that clash or combine with the hour pillar.
- Beware of hindsight: if you know what happened first and then look for reasons in the chart, almost any chart will offer some. The more events you use, and the earlier you write them down before comparing, the harder it is to fool yourself.
- The result is only "more likely": rectification can rule some hours out, but it rarely leaves just one.
Methods to ignore
You can tell the hour from the crown whorl on someone's head, or how they sleep.
Rules of thumb like these contradict each other from one book to the next and have no consistent basis. We do not use them.
Birth order among siblings reveals the hour.
The popular "birth order sets the hour" rhymes differ from source to source, and twins born minutes apart have different birth orders but may share the same hour, which makes no sense on its own terms.
A face reader can "read the hour" most accurately.
Face reading and BaZi are two different systems; using one to fix the other only stacks up the errors of both. A record, or a relative who was there, is always more reliable.
How we counted: we took every fourth day from 1960 to 2005, 4,201 birthdays in all, cast a chart for each of the twelve hours from Early Zi to Hai, and used our engine to compare strength, useful god and structure across the twelve.
Seen another way, for most people more than half of the twelve hours reach the same conclusions. Narrowing it to two or three hours is often enough.
All twelve hours at once: does your chart need the hour?
Enter your Gregorian birthday. The tool casts a chart for each of the twelve two-hour periods from Early Zi to Hai (plus the Late Zi hour) and marks which conclusions about strength, useful god and structure hold whatever the hour, and which change. Everything is calculated in your browser; nothing is uploaded.
Uses your Gregorian birthday, with the day changing at 11 p.m. If you know the rough time of day (say, "morning"), just read those rows.
A straight word: without the hour pillar, a quarter of the chart is missing
A BaZi chart has four pillars, and each missing one is a missing piece of the puzzle. Three pillars still show a great deal, but if your strength sits right on the line, you were born on a solar term day, or the hour decides your structure, the conclusions will wobble without it. We would rather mark what can change with the hour than pretend to know it for you. Everything on this site is for reference and entertainment.
Start by casting the possible hours
Enter your birthday and the tool lists all twelve hours; look only at the rows within the time of day your family remember, and you will see whether you need to narrow it further.
Recovering your birth hour FAQ
Where can I find my birth time?
The birth certificate is the most reliable source, followed by child health records, the hospital's records (old ones are usually destroyed) and family papers. Civil registration often records only the date.
What if family only remember roughly when I was born?
Match what they remember to two or three likely periods, then read only those rows in the twelve-hour tool. If they agree on strength and the useful god, you don't need to narrow it further.
Is birth time rectification accurate?
It can only say "more likely." Checking against events can rule some hours out but rarely leaves just one, and you have to guard against finding reasons after the fact.
Can hair whorls or sleeping position tell my birth hour?
These rules of thumb contradict each other from source to source and have no consistent basis, so we do not use them.