Birth Date Calculator
Find someone's birth date range from their age on a known date, or calculate exact age from a date of birth in years, months, weeks, days and hours, with your next birthday, the weekday you were born and your Hebrew birth date.
Age calculator by date of birth
Birth date calculator: find a birth date from an age
Birth date calculator: calculate birth date from age
If you know someone's age on a given date (from an obituary, census, ship manifest or court record), they were born between the day after that date minus age + 1 years and that date minus age years. Someone who was 36 on November 4, 2026 was born between November 5, 1989 and November 4, 1990. Two such records with different dates narrow the range; genealogists call this a born date calculator.
Calculate age using date of birth
Count whole years from the birth date, then whole months, then the remaining days. Born May 15, 1990, on November 4, 2026 you are 36 years, 5 months, 20 days old, or 437 months (calculate age in months by multiplying years by 12 and adding the months). The calculator also gives weeks, days, hours and your next birthday.
Birthday day calculator and Hebrew calendar calculator
The day-of-the-week box shows what day you were born (May 15, 1990 was a Tuesday). The Hebrew date uses your browser's built-in Hebrew calendar conversion, useful for Hebrew birthdays and bar or bat mitzvah dates; note that a Hebrew date begins at sunset the evening before, so a birth after sunset belongs to the next Hebrew day.
Common questions
How do I calculate my age from my date of birth?
Count full years, then months, then days. May 15, 1990 to November 4, 2026 is 36 years, 5 months, 20 days.
How do I find a birth date from an age?
Someone who was 36 on November 4, 2026 was born between November 5, 1989 and November 4, 1990.
How many months old am I?
Years × 12 + extra months; 36 years 5 months is 437 months.
What day of the week was I born?
Enter your birth date; May 15, 1990 was a Tuesday.
How do I convert my birthday to the Hebrew calendar?
Enter your birth date; the calculator shows the Hebrew date (if born after sunset, use the next day).
Sources
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General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.