How to Calculate Age from Date of Birth

To calculate age, compare the date of birth with the target date and adjust for whether the birthday has passed.

Basic Method

Subtract the birth year from the target year. Then check whether the birthday has already happened in the target year.

Example

If someone was born on 10 January 2000 and the target date is 10 January 2026, the age is 26 years.

Common Mistake

Many people subtract years only and forget to check whether the birthday has already passed.