Age Calculator

Calculate age in years, months and days, plus useful totals and your next birthday.

Age calculations use calendar dates. Total weeks are shown as completed weeks. For February 29 birthdays, the next birthday is treated as February 28 in non-leap years.

How to use the age calculator

Enter a date of birth and the date you want to measure to. The second date is set to today by default, but you can change it to any past or future date. Press Calculate age to see:

  • Your exact age in years, months, and days
  • Your age as total months, weeks, and days
  • The date of your next birthday and how many days are left until it
  • The day of the week you were born

Example

Someone born on March 15, 1990 is, on October 28, 2026, exactly 36 years, 7 months, and 13 days old. That is 439 months, 1,910 full weeks, or 13,376 days. They were born on a Thursday, and their next birthday is March 15, 2027, which is 138 days away.

How exact age is worked out

The calculator counts on the calendar, the same way you would by hand:

  • First it counts the full years since the birth date.
  • Then it counts the full months since the last birthday.
  • Finally it counts the remaining days.

Because months have different lengths, “1 month” doesn’t always mean the same number of days. That’s why the calculator also shows the total number of days, which is always exact.

Useful ways to use it

  • Forms and applications: check an exact age for a school, sports team, or visa cut-off date.
  • Milestones: find out when you or someone in your family will turn 10,000 days old (about 27 years and 4 months).
  • Planning: set the second date in the future to see how old someone will be at a wedding, a graduation, or retirement.
  • Anniversaries: enter a wedding date or a start date at work instead of a birth date to see how long it has been.

Age in different countries

Not every country has always counted age the same way. In South Korea, for example, a traditional system counted a baby as one year old at birth and added a year every New Year’s Day. In 2023, Korea officially adopted the international way of counting for legal and administrative purposes, which is the method this calculator uses.

Common questions

What about birthdays on February 29?

In years that are not leap years, the calculator treats February 28 as the birthday when working out your next birthday.

Why is the number of weeks a whole number?

Total weeks show completed weeks only. Any extra days are not rounded up.

Related tools

Search
Scroll to Top