Age Calculator

Enter a date of birth to see the exact age — years, months, days, and how long until the next birthday.

—Years / months / days
—Total days
—Total hours
—Next birthday in

How age is calculated

Age is counted the way calendars work: full years first, then full months, then leftover days. For example, from 2000-03-15 to 2026-09-06 is 26 years, 5 months and 22 days. A person is legally considered to reach their next age on the anniversary of their birth date, which is why the "next birthday" countdown matters for everything from school enrollment to retirement planning.

Frequently asked questions

How does it handle leap years and month lengths?

Properly. Months of different lengths and February 29 birthdays are handled by calendar rules — someone born on Feb 29 has their birthday counted on Mar 1 in non-leap years for the countdown.

Can I calculate someone's age on a past or future date?

This tool measures from birth to today. For any other target date, use our Date Difference Calculator.