Age Calculator

About this tool

Enter a birth date to see an exact age in years, months, and days. The age is calculated as of today by default; set a different reference date to find out how old someone was, or will be, on a particular day — a retirement date, an exam cut-off, a historical event.

How the calculation works. Age is worked out with calendar-aware date arithmetic, not by dividing a number of days. It counts complete years from the birth date to the reference date, then complete months, then the leftover days — the same way a person would say "37 years, 4 months, and 12 days." Because it steps through the actual calendar, months of different lengths and leap years are handled correctly.

Leap-year birthdays. Someone born on 29 February has a real birthday only in leap years. Between those, this tool treats the anniversary as falling at the end of February, so the age ticks over on 28 February / 1 March consistently rather than skipping three years in four.

Month-end edge cases. Counting whole months from 31 January to 28 February gives one month, not zero, because a full calendar month has passed even though the day number is lower. The leftover-days figure absorbs the difference.

Time zones don't matter here. Both dates are treated as plain calendar dates with no time of day, so the result is the same wherever you are. If you need a precise duration down to hours and minutes, that's a different calculation — a duration, not an age.

To measure the gap between two arbitrary dates rather than an age from a birth date, use days between dates. For counting only working days, use the workdays calculator.

Frequently asked questions

What if the reference date is before the birth date?

The tool shows a validation message rather than a negative age. Pick a reference date on or after the birth date.

Does it handle leap years?

Yes. The calculation uses calendar-aware arithmetic, so leap days and 29 February birthdays are counted correctly.

How is a 29 February birthday treated in a non-leap year?

The anniversary is taken as the end of February, so age increases on 28 February / 1 March rather than only once every four years.

What time zone is used?

None — dates are handled as calendar dates with no time component, so your time zone doesn't affect the result.

Why does it show months and days instead of a decimal age?

Years-months-days is unambiguous and matches how age is normally stated. A decimal age depends on an assumed number of days per year (365, 365.25, or the exact year length) and can differ slightly between methods.

Can I use it for a future date?

Yes. Set the reference date in the future to see the age someone will reach on that day.