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Age Calculator

Work out an exact age in years, months and days, with totals in weeks, hours and minutes. Results use the Gregorian calendar and whole days, so time zones and daylight saving never change the answer.

Enter a birth date. The as-of date is today unless you change it.
Age (years, months, days)-
Total days lived-
Whole weeks lived-
Total hours lived-
Total minutes lived-
Days until next birthday-
Next birthday-
Weekday of birth date-
Age is counted in whole days on the proleptic Gregorian calendar, applied to every year from 1900 to 9999. Everything runs in your browser; no dates are sent or stored.

How it works

Exact age is measured from the birth date to the as-of date. Whole months are added to the birth date, keeping its day of the month. If that day does not exist in the target month, the last day of that month is used. The years and months are the most whole months that do not pass the as-of date, and the days are what remain. For example, a birth date of 2000-01-31 gives 2 months and 1 day by 2000-04-01.

Leap-day rule. A birthday on 29 February falls on 28 February in a year without 29 February. Someone born on 29 February 2000 therefore has their birthday on 28 February in 2001, 2002 and 2003, and on 29 February again in 2004.

Totals count whole days from the birth date to the as-of date. Weeks are whole weeks, rounded down. Hours and minutes are the days multiplied by 24 and by 1,440, so they ignore time zones and daylight saving.

Next birthday is this year's birthday if it is still to come, or next year's if it has passed. On the birthday itself the count is 0.

Birth dates must be from 1900 onward and must not be after the as-of date. Nothing you enter is sent anywhere or stored.