What is an age calculator?
An age calculator works out a person's exact age from their date of birth to today or to a selected date. It shows age in calendar years, months and days, plus total days, weeks, months and next birthday details.
How to calculate age
Start with the calculation date and subtract the birth date. If the birthday has not passed in the calculation year, subtract one year, then count the remaining calendar months and days.
Why exact age uses calendar dates
Exact age should use real calendar dates because months do not all have the same length. February, April and January cannot be treated as identical 30-day periods when you need an accurate age.
How leap years affect age
Leap years add an extra day in February, which affects total days lived and birthdays near the end of February. The calculator accounts for leap years and different month lengths automatically.
How 29 February birthdays are handled
If someone was born on 29 February and the target year is not a leap year, this calculator treats their birthday as 28 February for next birthday calculations.
How many days old am I?
Total days old is the number of calendar days between the date of birth and the calculation date. Total weeks is the whole number of seven-day periods inside that total.
How to calculate age on a future or past date
Choose a custom calculation date to see age on a future or past date. For example, born 1 January 2000 means 26 years old on 1 January 2026. Born 15 June 1990 means 35 years, 10 months and 15 days on 30 April 2026. Being 18 years old means the 18th birthday has passed.