How is age in years, months, and days computed?

The tool counts complete calendar years first, then complete months, then leftover days — the same way ages are stated officially. Varying month lengths and leap years are handled by the calendar arithmetic.

What if the birthday is February 29?

In non-leap years the birthday is treated as March 1 for the countdown, which matches the most common legal convention.

Age Calculator

Calculate someone's exact age from their date of birth: full years, remaining months and days, and the total number of days lived. You can compute age as of today or as of any date you choose (useful for forms and official documents), and the tool also counts down the days to the next birthday.

Calculators

Date of birth

Age as of

Defaults to today

Private by default

This tool runs entirely in your browser. Your data is never uploaded to a server.

How to use

3 clear steps.

Enter the date of birth.
Optionally change the "as of" date (defaults to today).
Read the exact age in years, months, and days, and the days until the next birthday.

Good to know

Frequently asked questions

How is age in years, months, and days computed?: The tool counts complete calendar years first, then complete months, then leftover days — the same way ages are stated officially. Varying month lengths and leap years are handled by the calendar arithmetic.
What if the birthday is February 29?: In non-leap years the birthday is treated as March 1 for the countdown, which matches the most common legal convention.