Age calculator in years, months and days
Enter a date of birth and a reference date. The calculator counts completed calendar years and months, the remaining days and the total number of calendar days. It does not use a time of birth or time zone.
Calculate calendar age
Worked example
From 15 March 1990 to 20 May 2026, the result is 36 years, 2 months and 5 days. The reference date is an example, not today’s date.
How months of different lengths are counted
The calculator counts completed calendar anniversaries. If the original day does not exist in a target month, it uses that month’s last day. Under this rule, 31 January to 28 February counts as one month; 29 February 2024 to 28 February 2025 counts as one completed year.
How to avoid unexpected results
- Check the reference date; its initial value comes from the device calendar.
- The reference date must be the same as or later than the birth date.
- Times of day and time zones are not included.
- Contracts, benefits and registration systems may define age cutoffs differently; check the rules of the relevant service.
Dates are processed in this page in your browser. For a general date interval, use the date-difference calculator.
Frequently asked questions
Does this use the exact time of birth?
No. It compares calendar dates only. Hours, minutes and the time zone of an event are not part of the calculation.
Why can one month be 28, 29, 30 or 31 days?
Calendar months have different lengths. This calculator counts full calendar anniversaries and clamps a missing day to the last day of that month.
Can this determine eligibility for a benefit or contract?
It provides a calendar calculation, not an official eligibility decision. The organization or applicable rules may use a specific cutoff method.