How to calculate your exact age in years and days

Updated 2026-11-13

Quick answer

Subtract your date of birth from the date you want, year by year, month by month and day by day. Born on 15 June 1995 and measured on 1 January 2026, you are 30 years, 6 months and 17 days old.

Steps

Write down your date of birth and the date you are measuring to, which is usually today. Here: 15 June 1995 and 1 January 2026.
Count the whole years: from 15 June 1995 to 15 June 2025 is 30 years.
Count the whole months after that: 15 June 2025 to 15 December 2025 is 6 months.
Count the days left: 15 December 2025 to 1 January 2026 is 17 days.
Or enter the dates in the age calculator, which also gives your total days and weeks and your next birthday.

When the day of the month is bigger than the month is long

If you were born on the 31st, the month count has to deal with shorter months. Born on 31 January 1990 and measured on 1 March 2026, you are 36 years, 1 month and 1 day old: 31 January plus one month lands on the last day of February, the 28th, and one more day takes you to 1 March.

The usual method is to count whole months first, using the last day of a shorter month when the date does not exist, and then count the days that remain.

Leap-day birthdays

A birthday on 29 February happens only in leap years. The calculator treats a 29 February birthday as falling on 1 March in other years. Someone born on 29 February 2000 is 0 years, 11 months and 30 days old on 28 February 2001, and turns 26 on 1 March 2026. Some places use 28 February instead, so use the rule that your official documents follow.

What else the date of birth tells you

The age calculator also shows the weekday you were born on, the total days and weeks you have lived and the days until your next birthday. Change the second date to find your age on a future or past date, which is useful for age limits on forms, exams and policies.

Common questions

How do I calculate age from date of birth?

Subtract the birth date from the later date in years, months and days, borrowing from the previous unit when a part comes out negative.

How do I find my age on a future date?

Change the second date in the age calculator to the date you want.

How is a 29 February birthday handled?

In non-leap years the calculator counts the birthday on 1 March. Check which rule your document uses.

How many days old am I?

The age calculator shows the total days and weeks lived, as well as years, months and days.