How to calculate your exact age

1.
Enter the date of birth
Pick it from the calendar or type it in.
2.
Set the "age on" date
Age is calculated for today by default. You can choose any other date, such as a school start date, an exam or an application deadline.
3.
Read the result
You see the age in years, months and days, the total days, weeks and months lived, and the countdown to the next birthday.

How age is calculated

Age is the number of full years since the date of birth. A new year of life is completed on the calendar day that matches the birthday, so someone born on 15 May 1990 turned 36 on 15 May 2026. The rest of the age is the full months and days since the last birthday.

Example: on 11 October 2026, a person born on 15 May 1990 is 36 years, 4 months and 26 days old. They have lived 13,298 days, and their 37th birthday is 216 days away. They were born on a Tuesday.

This is the chronological age used in everyday life, by schools, doctors and most official forms. Some countries traditionally count age differently (for example, East Asian age reckoning that starts at one), but international documents use the method above.

Birthdays on 29 February

People born on 29 February only have a "real" birthday every four years. In common years this calculator treats 28 February as the day the next year of life is completed, which is the rule used in Polish law and in many other legal systems. Some legal systems use 1 March instead, so if an exact legal date matters (for example, coming of age), check the rule in your country.

Age in days, weeks and months

Besides years, the calculator shows the total number of days, weeks and months lived. For a person born on 15 May 1990, on 11 October 2026 that is 13,298 days, or 1,899 full weeks plus 5 days, and 436 full months. Every leap day (1992, 1996 and so on up to 2024) is included.

Round "day birthdays" are rarer than you might think: the same person celebrated day 10,000 on 30 September 2017 (aged 27), day 15,000 falls on 9 June 2031 and day 20,000 on 15 February 2045. You can find such dates for any birthday with the add days to a date calculator.

Common mistakes when working out age

Simply subtracting birth years is the classic error: someone born in 1990 can be 35 or 36 in October 2026 depending on whether the birthday has passed. Other mistakes are counting every month as 30 days and forgetting leap days when counting days alive (there are 9 of them in 36 years). To measure the gap between any two dates, not just from a birthday, use the days between dates calculator.

Frequently asked questions

How do I calculate how old I am?

Subtract your birth year from the current year, and subtract one more if your birthday has not happened yet this year. The calculator does this automatically and also gives the months and days.

How many days old am I?

The "Days lived" box shows the exact number of days since your birth. Leap years are included, so the result is accurate to the day.

What day of the week was I born?

After you enter your date of birth, the calculator shows the weekday. For example, 15 May 1990 was a Tuesday.

Can I calculate age on a past or future date?

Yes, change the "Age on" field. This is useful to check how old a child will be on 1 September, or how old someone was on the day of an event.

When does someone born on 29 February turn a year older?

This calculator uses 28 February in common years. Some countries use 1 March for legal purposes, so check the local rule if it matters.

Is my date of birth sent anywhere?

No. All calculations run in your browser and the date of birth is never stored or sent to a server.

Updated: October 10, 2026