Age Calculator

How to use the age calculator

1. Enter the date of birth.
2. Optionally change the date to calculate as of.
3. Read the exact age and the days until the next birthday.

About this tool

Age sounds like simple subtraction until months get involved. Months have different lengths, so 'one month after 31 January' has no obvious answer, and leap years shift the day count. This calculator counts whole years first, then whole months, then the remaining days — the convention used for legal age and for most official forms.

It also reports the total number of days, which is the unambiguous figure when you need to compare two spans rather than describe one.

Common uses

• Filling in an exact age on a form.
• Working out an age on a specific past or future date.
• Counting down to a birthday or anniversary.

Frequently asked questions

How are leap years handled?

The calculation uses real calendar dates, so leap days are counted where they occur. Someone born on 29 February is treated as having their birthday on 1 March in non-leap years.

Can I calculate age at a past date?

Yes. Change the second date to any date you like and the age is calculated as of that day.