Age Calculator

English

How to use the age calculator

This age calculator works out your exact age from your date of birth, counted in full years, months and days, the way people normally state age. It also gives the same span as total months, weeks, days and hours, the weekday you were born on and a countdown to your next birthday.

1. Enter the date of birth.
2. Leave the second date on today, or change it to any later day, such as the closing date of a job application or the start of a school year.
3. Read the result. It updates as you type, and the bar under the countdown shows how far you are through the current year of your life.

How exact age is calculated

Exact age is counted like a calendar, not by dividing days by 365. The calculator first finds the last birthday on or before the chosen date, which gives the full years. From there it counts whole months to the last monthly anniversary of the birth day, then the remaining days.

Example: born 15 June 1990, on 11 October 2026. The last birthday was 15 June 2026, so the age is 36 years. From 15 June to 15 September is 3 full months, and from 15 September to 11 October is 26 days. The answer is 36 years, 3 months and 26 days, which is 13,267 days in total.

When the birth day does not exist in a shorter month, for example the 31st in a 30-day month, the monthly anniversary falls on the last day of that month. Total hours are total days × 24, so they ignore the time of birth and daylight saving changes, which is why the label says approximate.

Why dividing by 365 gives the wrong answer

A quick shortcut is to divide the number of days by 365. It drifts because about one year in four has 366 days. The table shows how many days the same age can contain, depending on how many 29 Februarys fall inside it.

Near a birthday, the shortcut can be a day early or late, which matters when an age limit decides whether someone can apply, enrol or retire. Counting real calendar dates avoids that.

Leap year birthdays: born on 29 February

If you were born on 29 February, your birth date only appears every four years (with a few century exceptions such as 1900 and 2100). In other years there is no single rule for when the birthday falls. Some people and some legal systems use 28 February, others use 1 March. When you enter 29 February, the calculator shows a switch so you can pick the rule that applies to you. It changes the countdown, the next birthday date and, for a day or so each year, the years-months-days result. Leap years follow the Gregorian rule: divisible by 4, except century years, unless divisible by 400.

Tips and limits

• Age limits. For a form that says "under 35 on 1 January", set the second date to 1 January and check the years figure. Each organisation decides how its limit is counted, so follow its own wording.
• Day of the week. The weekday of birth uses today's Gregorian calendar. Dates before a country switched from the Julian calendar may not match old local records.
• Time zones. Only dates are used, not the time of birth, so someone born late at night in another time zone may count a birthday a day differently.
• Privacy. Everything runs in your browser. Your date of birth is not sent or stored anywhere.

Frequently asked questions