Age Calculator
Enter Birth year, Birth month, and Birth day. Enter As-of year, As-of month, and As-of day (today, or any date you want to test). Calculate. Years is the bir…
Introduction
Count chronological age from Birth year, Birth month, and Birth day to an As-of year, As-of month, and As-of day. The headline is whole years. The rows below are the same span as months, or weeks, or days, or hours, or minutes (not years plus leftover months).
How to use
- Enter Birth year, Birth month, and Birth day.
- Enter As-of year, As-of month, and As-of day (today, or any date you want to test).
- Calculate. Years is the birthday age. The other rows rewrite that span in one unit each.
Formula
Years: As-of year minus Birth year, minus 1 if the As-of month/day is before the birthday.
Months: (As-of year minus Birth year) x 12, plus As-of month minus Birth month, minus 1 if As-of day is before Birth day.
Days: calendar days from the birth date to the As-of date (same-day difference is 0). Weeks: whole days / 7, dropping the remainder. Hours: days x 24. Minutes: hours x 60. Hours and minutes assume the same clock time on both dates.
Example
Defaults: born 15 Jun 1990, as of 19 Aug 2026. Years = 36. Months = 434. Weeks = 1,887. Days = 13,214. Hours = 317,136. Minutes = 19,028,160.
Limitations
This does not print a mixed remainder (36 years 2 months 4 days). Hours and minutes ignore clock time. Invalid dates (31 Feb) fail. It is not a next-birthday, pregnancy, or legal-age tool.
FAQ
How old was I on this date?
Set As-of year, As-of month, and As-of day to that date. Every row uses that as-of date.
How many days old am I?
Use the Days old row. Weeks, hours, and minutes are the same span, not extra time.
Is this chronological age?
Yes. Years step on the birthday. Months step on the same day of the month. The rows are alternatives, not a remainder stack.