Age Calculator

Calculates exact age as a calendar-style years, months and days breakdown between a birth date and a reference "as of" date, plus the total number of elapsed days.

Enter a birth date and an "as of" date (defaulting to today). The years/months/days breakdown and total elapsed days update immediately. The birth date cannot be later than the "as of" date.

A birth date of 2000-01-01 with an "as of" date of 2026-09-21 gives 26 years, 8 months and 20 days — computed from full calendar years and months, with the remaining days counted last.

The calculator subtracts calendar components and borrows the length of the previous month whenever the day difference comes out negative; total days is derived separately from the millisecond difference divided by 24 hours.

Because the calculation works on real calendar dates rather than a fixed 365-day year, leap years are handled automatically and don't need any special input.

Month-end dates, unusual browser date parsing and daylight-saving transitions can produce edge cases — don't rely on the result alone for legal, eligibility or contractual age decisions.

The calculation runs locally in your browser; the dates you enter are not uploaded.