Age Calculator: What It Calculates
Age Calculator works from exact calendar dates rather than estimates. Entering the correct dates is essential because the number of days in a month and leap years are part of the calculation.
The Formula or Method
Age is determined from the birth date to the target date, accounting for whether the birthday has occurred in the target year.
Avoid date-entry errors
Check the day, month, and year before calculating, especially when comparing dates from different formats.
Using Age Calculator
Enter the two dates using the displayed format. Check the year as well as the month and day, then compare the resulting age or interval with the calendar dates you entered.
- Enter the first relevant date.
- Enter the comparison or target date.
- Calculate the elapsed age or interval.
- Check the result against the calendar before relying on it.
Worked Example
A person born on June 15, 2000 is 26 on September 8, 2026.
Checking the Result
For an exact calendar result, use the actual dates rather than approximate year counts. A date-based answer can differ from a simple subtraction of years because birthdays and month lengths matter.