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

The calculator counts the number of full years between the two dates, then the number of full months remaining, then the number of days remaining — carrying over from the previous month or year whenever the day or month hasn't been reached yet.

Does the calculator account for leap years?

Yes. Because it works with actual calendar dates rather than a fixed 365-day year, leap years (like February having 29 days) are automatically handled correctly.

Can I calculate the age difference between two people?

Yes — enter one person's birth date as the "birth date" and the other person's birth date as the "as of" date to see the exact difference between them.

Age Calculator

Find your exact age in years, months, and days, plus your total days, weeks, and months lived, from your date of birth.

Date of birthAge as of

Enter both dates to calculate age.

How It Works

Counting full years, months, and days

The calculator compares your birth date to the target date and counts the number of complete years, then complete months, then remaining days between them.

Handling different month lengths

Because months have different numbers of days, the calculator accounts for month length (including leap years) when counting full months and days.

Example Calculation

Someone born on June 15, 1990 is, as of September 4, 2026, exactly 36 years, 2 months, and 20 days old.

Common Mistakes

Assuming every year has exactly 365 days, which throws off manual day-count calculations during leap years.
Forgetting that someone's "age in years" doesn't increase until their birthday has actually passed in the current year.
Manually subtracting month numbers without borrowing correctly when the day-of-month for the birth date hasn't been reached yet.

Frequently Asked Questions

How is age in years, months, and days calculated?: The calculator counts the number of full years between the two dates, then the number of full months remaining, then the number of days remaining — carrying over from the previous month or year whenever the day or month hasn't been reached yet.
Does the calculator account for leap years?: Yes. Because it works with actual calendar dates rather than a fixed 365-day year, leap years (like February having 29 days) are automatically handled correctly.
Can I calculate the age difference between two people?: Yes — enter one person's birth date as the "birth date" and the other person's birth date as the "as of" date to see the exact difference between them.