How to use this age calculator
This age calculator works with calendar dates rather than using an average number of days per year. That makes the year, month, and day result easier to understand.
Choose today or another comparison date to calculate age at a specific point in time.
Formula
Age is calculated as the calendar difference between the birth date and the selected comparison date.
Worked example
A person born on 10 January 2000 is 26 years old on 10 January 2026.
Step-by-step
- Enter the date of birth.
- Choose the date to calculate age on.
- Calculate to see years, months, days, and total days.
Frequently asked questions
Does the calculator include leap years?
Yes. It uses real calendar dates, including leap years.
Can I calculate age on a past date?
Yes, as long as the comparison date is not before the birth date.
Why can total days differ from years multiplied by 365?
Calendar years have different lengths because of leap years.