Age Calculator
Find how many years, months, and days have passed from a birth date to an as-of date. Dates only, no time needed.
Age
How it works
The tool compares two calendar dates and counts the whole years, months, and days between them. It uses calendar months, so a birthday on the 29th, 30th, or 31st is counted on the last day of that month when the month is shorter.
Examples
- Born February 29, 2000 and measured on February 28, 2023 gives an age of 23 years.
- Born May 15, 1990 and measured on August 23, 2026 gives an age of 36 years, 3 months, and 8 days.
Need a week or a span already in mind? Try the Weeks Between Dates tool.
Frequently asked questions
How are leap-day birthdays handled?
A person born on February 29 turns a year older on February 28 in years without a February 29.
Does the tool need the time of birth?
No. Age is counted by calendar dates only, so a birth time is not needed and does not change the result.
What does the as-of date mean?
It is the date you want the age measured against. It starts today but you can change it to look forward or back.
Why does an end-of-month birthday sometimes land on a different day?
A birthday on the 29th, 30th, or 31st of a month is counted on the last day of that month when the month is shorter.
Is age the same as calendar days since birth?
Not exactly. Age is expressed in whole years, months, and days using calendar months, so the result can differ from a plain total of days.