How the Age Calculator works
Enter a date of birth and, optionally, the date you want the age for. The calculator counts full years first, then full months, then the remaining days — the same way people state their age. It also shows the age as total months, total weeks, total days and approximate hours, the day of the week the person was born and how many days remain until the next birthday.
Counting years, months and days
Someone born on 20 May 1990 is 36 years old on 20 May 2026. On 16 October 2026 they are 36 years, 4 months and 26 days old: four full months take them to 20 September, and 26 more days take them to 16 October. Months have different lengths, so the day count always restarts from the same day of the month as the birthday.
Birthdays on 29 February
People born on 29 February have a real birthday only in leap years. In other years this calculator treats 28 February as the birthday for the countdown, which is the convention most often used for everyday purposes. Legal rules on when a leap-day birthday counts can differ between countries.
Age on a specific date
Use the optional “Age on this date” field to find someone’s age at a past event, on a form’s cut-off date, for a school entry date or for an upcoming trip. The result is the completed years, months and days on that date.
Chronological age vs corrected age
This is chronological age — time since birth. For babies born prematurely, doctors often use corrected age for development checks; use the Corrected Age Calculator for that. To see the conception date and other facts from a birthday, try the Birth Date Calculator.