Age Calculator

Enter your date of birth to get your exact age in years, months and days — plus your total days lived, the day of the week you were born on, and how long until your next birthday.

How age is calculated

Age is counted the way people actually use it: you are a year older on your birthday, not on the day you pass 365 days. The calculator subtracts calendar components rather than dividing a total number of days, which is what makes the result match your real birthday.

It starts by subtracting the birth year from the current year, then the month, then the day. If the day comes out negative it borrows the number of days from the previous month; if the month comes out negative it borrows twelve months from the year count.

Why not just divide by 365?

Because years are not all the same length. A leap year has 366 days, and dividing a total day count by 365.25 drifts away from the calendar by hours at a time — enough to report the wrong age on the day before or after a birthday.

Calendar subtraction avoids the problem entirely. It borrows the real length of the preceding month, so February, leap days and 31-day months are all handled correctly.

This is the same method used by the ISO calendar arithmetic in most date libraries.

Example calculation

Someone born on 14 March 1990, calculated on 20 January 2026, has not yet had their birthday this year. Subtracting years gives 36, but because January comes before March the calculator borrows a year, leaving 35 years.

It then counts the months from March to January — ten — and the days from the 14th to the 20th, which is six. The exact age is 35 years, 10 months and 6 days.

14 Mar 1990 → 20 Jan 2026 = 35 years, 10 months, 6 days

What the calculator shows you

Result	What it means
Years, months, days	Your exact age in calendar terms
Total days	Every day you have been alive, leap days included
Total weeks and hours	The same span in smaller units
Day of the week born	Derived from the calendar date
Next birthday	Days remaining and the weekday it falls on

Leap years and 29 February

Roughly one year in four has an extra day. A year is a leap year if it divides by 4, except century years, which must also divide by 400 — so 2000 was a leap year but 1900 was not.

People born on 29 February have a birthday only every four years. Most jurisdictions treat 1 March as the legal birthday in common years, and this calculator follows the same convention.

Frequently Asked Questions

How does the calculator handle leap years?

Automatically. Because it subtracts calendar dates rather than dividing a day count, leap days are included in the totals and never shift your birthday.

What age am I if I was born on 29 February?

In a common year the calculator advances your age on 1 March, which matches how most countries treat leap-day birthdays in law. In a leap year your birthday falls on 29 February as normal.

Why does my age in months not match my age in days ÷ 30?

Months vary from 28 to 31 days, so no fixed divisor is right. The calculator counts real calendar months, which is why the two figures differ slightly.

Can I calculate age at a past or future date?

Yes. Change the second date from today to any date you like and the calculator will work out the age on that date, which is useful for eligibility cut-offs and school year rules.

Is my date of birth stored anywhere?

No. The whole calculation runs in your browser and nothing is sent to a server or saved.