How calendar age works
Age is expressed in complete years, then complete months, then remaining days. That reflects calendar boundaries rather than dividing the total days by a fixed 365-day year.
Choose any comparison date
The second date defaults to today, but you can change it to calculate age on a past or future date. The comparison date must not be earlier than the birth or start date.
Leap years and month lengths
The calculation uses real calendar dates, so February and leap years are accounted for. People born on 29 February may observe birthdays differently depending on local custom or law.
Important uses
This tool is useful for planning and general information. For legal eligibility, benefits, insurance or identity records, confirm the applicable rules and use the date recorded by the responsible authority.