🎂 Age Calculator

What this age calculator does

Enter a date of birth and, if you want, a second date to measure the age on. If you leave the second date as today, you get your age now. The result shows your age in years, months and days, the same age as total months, total days and approximate total hours, the number of days until your next birthday and the day of the week you were born. It runs in your browser, so your date of birth is not sent anywhere.

How the age is worked out

The calculator subtracts the birth date from the second date year by year, then month by month, then day by day. If the day of the month comes out negative, it borrows the length of the previous month. If the months come out negative, it borrows a year. Total days is the exact number of calendar days between the two dates. Total hours is that figure times 24 and is only approximate because it ignores the time of day you were born.

Worked example

Born 15 January 1990, measured on 5 October 2026:

• Years: 2026 − 1990 = 36. Months: October is 9 months after January. Days: 5 − 15 = −10, so one month is borrowed. September has 30 days, which gives 20 days and 8 months.
• Age: 36 years, 8 months, 20 days.
• Total days lived: 13,412.
• Next birthday: 15 January 2027, which is 102 days away.
• Day of birth: Monday.

Edge cases

• Born on 29 February. In years that are not leap years there is no 29 February. This calculator treats 1 March as the birthday in those years. Legal conventions differ by country; some treat 28 February as the birthday for legal purposes, so check the rule that applies if the exact date matters.
• Different month lengths. "One month" is not a fixed number of days. From 31 March to 1 May is counted as 1 month 0 days by this tool. Other tools may count it differently.
• Age on a future or past date. Use the second date to check an age on a cut-off date, such as a school intake date or the date of a visa application. The second date must not be earlier than the date of birth.
• Birthday today. The "next birthday" box shows a birthday message on the day itself.

Where an exact age matters

School and nursery cut-off dates, age limits on forms and competitions, retirement and pension ages, insurance and some visa categories all depend on age on a stated date, not on the year of birth alone. Rules also differ between countries on how age is counted. In some East Asian traditions, for example, a person is considered one year old at birth, so always confirm which method an official form uses. Parents often want a child's age in months for a doctor's visit, and the total-months figure covers that.