Age Calculator
Determine exact age from a birth date, or years between two dates. Years and months follow the calendar, including leap years and shorter months.
Worked examples
Example 1
15 March 1990 to 15 October 2026
15 March 1990 to 15 October 2026 is 36 years, 7 months, 0 days. That is 439 completed months, 1909 completed weeks, and 13363 total days.
Example 2
29 February 2000 to 28 February 2021
29 February 2000 to 28 February 2021 is 21 years, 0 months, 0 days. That is 252 completed months, 1095 completed weeks, and 7670 total days.
Example 3
31 January 2024 to 1 March 2024
31 January 2024 to 1 March 2024 is 0 years, 1 month, 1 day. That is 1 completed month, 4 completed weeks, and 30 total days.
Common questions
What happens to a 29 February birthday in a non-leap year?
The birthday is observed on 28 February, the last valid day of the month. On 28 February the age is an exact number of years. On 1 March it is one day past that anniversary. In the next leap year, the birthday returns to 29 February.
Are months treated as 30 days and years as 365 days?
No. Years and months follow the calendar. A month is complete only when the same day of the month arrives, or the last valid day when that day does not exist. Total days are the exact number of calendar days between the two dates.
What do completed months and completed weeks mean?
Completed months are full calendar months already reached. Extra days stay in the day count and are not rounded up to another month. Completed weeks are groups of 7 completed days, so 10 days is 1 completed week, not 2.