Age Calculator

Calculate your exact age in years, months and days from your date of birth, plus total weeks and days lived and a countdown to your next birthday.

How to use the age Calculator

  1. Pick the date of birth.
  2. Pick the age on this date.
  3. The result updates instantly as you type. There is no button to press.
  4. Use Copy result to copy the figures, or Copy link to share a link that reopens the age Calculator with the same inputs.

How it works

Working out an exact age by hand is fiddly because months have different lengths and leap years add an extra day every four years. This calculator counts it precisely: full years first, then full months, then the remaining days, the same way ages are stated on official documents and in everyday speech.

The method compares the birth date with the target date one unit at a time. It subtracts years, then months, and if the day of the month hasn't been reached yet it borrows a month and adds that month's actual number of days. For example, from January 31 to March 1 is 1 month and 1 day in a non-leap year. Totals in weeks and days count every calendar day between the two dates, using your device's calendar, so they are not affected by daylight saving changes.

You can change the second date to find your age on any day, past or future: on a retirement date, at the start of a school year, or on the day a contract or visa is signed. If you were born on February 29, your birthday falls on March 1 in years without a leap day, which is the rule used in many countries, though some legal systems use February 28.

Formula

years = target year − birth year (minus 1 if the birthday hasn't happened yet) months = remaining whole months days = remaining days (borrowing the length of the previous month if needed) total days = (target date − birth date) in calendar days

Example

Someone born on June 15, 1990 is 35 years, 3 months and 20 days old on October 5, 2026: from June 15, 1990 to June 15, 2026 is 35 years, then to September 15 is 3 more months, and from there to October 5 is 20 days. That is 13,261 days in total, or about 1,894 weeks. Their next birthday is 253 days away.

Frequently asked questions

How is age calculated for someone born on February 29?

In years without February 29, this calculator treats March 1 as the birthday. Some countries legally use February 28 instead, so check local rules for official purposes.

Why do different sites give a different number of days?

Most differences come from whether the end date is counted, or from time zones. This calculator counts calendar days from the birth date up to, but not including, the end date.

Can I calculate age at a future date?

Yes. Change 'Age on this date' to any date, such as your next birthday, a graduation day or a retirement date.