Enter a date of birth and an as-of date to calculate completed calendar age and elapsed totals without assuming a fixed-length year.
Calculate with the Age Calculator
Dates are validated as calendar components before calculation.
Age Calculator results
How to use the Age Calculator
- Enter the required calendar dates, times, or rule values.
- Choose the counting convention or mode where offered.
- Select Calculate or press Enter.
- Review the result, basis, and limitations before using it.
Worked example
1 August 2000 to 1 August 2026 is exactly 26 years.
Assumptions
Date-only calculations use the proleptic Gregorian calendar and ignore clock time. Elapsed-time calculations and selected-zone conversions state their time basis separately.
Limitations
- A future date of birth is rejected.
- A 29 February birthday is observed on 28 February in non-leap years for next-birthday calculations.
Frequently asked questions
What date basis does the Age Calculator use?
The result uses calendar dates unless the page explicitly describes elapsed time or a selected time zone.
Can daylight-saving time change calendar-day totals?
No. Date-only calculations use normalized UTC day numbers. Elapsed timestamp and time-zone calculations are explicitly handled separately.
Are entered dates stored?
No. Calculations run in your browser and the entered dates are not saved or sent anywhere.