Age Calculator
Calculate age in years, months and days using a date of birth and a target date. You can use today's date or choose another date for a past or future calculation.
Calculate Your Age
Enter the date of birth and the date on which you want to calculate the age.
What Is an Age Calculator?
An age calculator is a date-based tool that calculates the time between a person's date of birth and another selected date.
Instead of manually counting calendar years and months, the calculator compares the dates and provides an easy-to-read result.
How Age Is Calculated
A basic age calculation starts by comparing the year, month and day of the birth date with the target date. The calculator then adjusts the result based on whether the birthday has occurred in the target year.
Why Month and Day Matter
Simply subtracting birth year from target year is not always enough. If the birthday has not happened yet during the target year, the completed age is one year lower.
Age in Years, Months and Days
An exact calendar-based calculation can provide a result such as:
This is different from simply converting the entire duration into a number of years because calendar months do not all contain the same number of days.
How Leap Years Affect Age Calculations
Leap years include an additional day in February. Because calendar dates can be affected by leap years, date-based calculations need to account for the actual calendar rather than assuming every year contains the same number of days for every purpose.
What Is a Future Age Calculation?
You can choose a future target date to calculate how old someone will be on that date.
For example, a birth date can be compared with a future birthday, an event date or another planned date.
What Is a Past Age Calculation?
You can also select a date in the past to determine how old someone was at that time, provided the target date is not earlier than the person's date of birth.
Common Age Calculator Mistakes
- Entering the wrong birth date.
- Selecting the wrong target date.
- Confusing the date and month fields when entering dates manually.
- Assuming every year or month has the same number of days.
- Subtracting only the birth year without checking the birthday.
When Can an Age Calculator Be Useful?
An age calculator can be useful for general date calculations, planning, educational exercises and checking age on a particular date.
It can also be useful when comparing dates without manually counting the months and days.
Important Note for Official Use
Some legal, administrative, educational or eligibility situations may have specific rules for determining age or an applicable cutoff date.
When the exact legal or administrative definition matters, check the rules of the relevant organization or authority rather than relying only on a general calculator.
Why Correct Dates Matter
The calculator can only calculate from the dates entered. A one-day or one-month error can change the result.
Always review both dates before relying on the result.
Age Calculator FAQ
Common questions about age calculations.
It compares the date of birth with a selected target date and calculates the calendar difference.
Yes. Enter the future date as the target date to calculate the age on that date.
Yes, provided the target date is not earlier than the birth date.
Yes. The date calculation uses the calendar dates entered, including leap-year dates.
Yes. The result is displayed as completed years, months and days.
It is a general date calculation. Official organizations may use specific rules or cutoff dates, so verify their requirements when necessary.