Age Calculator: Your Exact Age in Years, Months, and Days
Age in whole years hides the detail. Working out months and days as well gives the exact age on any date, with proper borrowing across months.
What is the Age Calculator?
Enter a birth date and the date to calculate the age at, and the tool works out the exact age with proper borrowing across months. The default as-of date is 1 November 2026, so you can check an age on a fixed date as well as today.
How to use it
- Enter the birth date as YYYY-MM-DD.
- Enter the date to calculate the age at.
- Click Calculate Age for years, months, and days.
Worked example
Born on 15 May 1990, a person is 36 years, 5 months, and 17 days old on 1 November 2026.
Why does the month count sometimes borrow days?
Because months have different lengths. If the as-of day is earlier in the month than the birth day, a month is borrowed and its days are added.
Frequently asked questions
Can I calculate an age in the past?
Yes. Set the as-of date to any date on or after the birth date.
What does total days lived mean?
The whole number of days between the two dates, ignoring the years-months-days split.