How to use this tool
Enter the Gregorian birth date and the date on which age should be measured. The result gives completed years, whether this year's birthday has passed, and the next anniversary with its countdown. The reference date defaults to today in the selected region and can be changed.
Rules and supported dates
Age increases on the anniversary. For 29 February, this tool uses 1 March in common years; this is not a legal eligibility decision.
Supported dates: 1900-01-01 to 2199-12-31
Worked example
Someone born on 2000-10-25 is 23 on 2024-10-24 and 24 on 2024-10-25. Subtracting only the years overstates age before the birthday.
Common question
Is this completed age or traditional nominal age?
It is completed age, rather than a system that starts at one and increments at New Year. For 29 February births, the common-year anniversary is 1 March here. Formal eligibility depends on the relevant institution's rules; this calculator gives a date result under an explicit convention.