Age Calculator

Enter a date of birth. Change the second date to find an age as it was, or will be, on any particular day.

Why the day count can surprise you

Months are not equal, so “three months” is a different number of days depending on which three months. This calculator counts calendar months properly rather than assuming 30 days, which is why the years-months-days figure and the total-days figure will not divide neatly into each other.

Leap years are handled directly. Someone born on 29 February has a birthday that only exists every four years; the next-birthday count uses 1 March in common years, which is the convention most legal systems follow.

Useful for forms

Visa applications, school enrolment and insurance forms often want an age as at a specific date rather than today. Set the second field to that date and read it off.

How this is worked out

Calendar months are counted properly rather than assumed to be 30 days, which is why the years-months-days figure will not divide evenly into the total-days figure. Leap years are handled directly, and for a 29 February birthday the next-birthday count uses 1 March in common years.

Common questions

Can I find my age on a past or future date?

Yes. Change the second date to any day and it calculates the age as at that date.

How are leap years handled?

Exactly. The day count is a true difference between the two dates, so leap days are included wherever they fall.