How it works
Completed years = difference in calendar years, minus one if the birthday has not yet occurred.
A worked example
Someone born 15 June 1990 is 36 completed years old on 23 September 2026.
What to keep in mind
Uses calendar dates in UTC to avoid daylight-saving offsets. A 29 February birthday reaches the next age on 1 March in non-leap years. Legal rules can differ.
A common question
Can I calculate age on a future date?
Yes. Choose any reference date on or after the date of birth.
Results use the assumptions above. Check critical measurements and dates independently.