Age Calculator
Free age calculator. Enter a date of birth and get an exact age in years, months and days, the total in weeks and hours, and how long until the next birthday.
What it does
Your age is the number of complete years, months and days between your birth and a chosen day. It sounds like simple subtraction and is not: months have different lengths, so the answer depends on which month you borrow from. This calculator counts whole months first and measures the remainder in days, which is why it gives a sensible answer for people born on the 31st or on 29 February.
How to use it
- Type your date of birth.
- Leave the second date as today, or change it to work out an age on any other day.
- Read the age, the totals in other units, and the countdown to the next birthday.
The arithmetic runs in your browser. Nothing you type is sent anywhere and nothing is stored, so you can use these with real numbers.
Frequently asked questions
How is someone born on 29 February treated?
They complete a year on 28 February in common years and on 29 February in leap years, which is the convention in most countries. This calculator follows it, so the age never jumps a day back and forth.
Why do other calculators disagree by a day?
Usually time zones. A date typed as text is often read as midnight UTC, which is the previous day in the Americas, so the age comes out one day short. This page does calendar arithmetic with whole numbers and never touches a clock.
What happens when the birth day does not exist in the target month?
Someone born on 31 January has no 31st in February. The month is counted as complete on the last day of that month, so 31 January to 1 March is one month and one day, not a negative number of days.
Can I use it to work out how long until a date?
For a past date, yes — put it in the first field. For a future date use the date calculator, which is built for intervals in both directions.
Wikipedia — Age
Wikipedia — Leap year
Wikipedia — February 29
Wikipedia — Gregorian calendar