Your result
How this calculation works
Age is calculated by comparing calendar dates and subtracting a year when the birthday has not yet occurred on the selected date.
Choose a date of birth and the date to calculate against. The calculator compares calendar dates and can also show when the next birthday occurs.
How to use this calculator
- Enter or choose date of birth.
- Enter or choose calculate age on.
- Select Calculate and review the result and assumptions.
Worked example
A person born on May 10, 2020 is 5 years, 1 month, and 2 days old on June 12, 2025. This is calendar age, not an estimate based on an average year length.
Frequently asked questions
Can I calculate age on a date in the past?
Yes. Choose any date on or after the date of birth in the “Calculate age on” field.
How are leap-day birthdays handled?
The age is based on completed calendar years. The next-birthday display follows the browser calendar date rules for the selected year.