Age Calculator
Enter a date of birth and calculate age in years, months and days.
An age calculator determines the elapsed calendar age between a date of birth and a reference date. It can also show the total number of days elapsed.
Enter the date of birth, optionally change the reference date, and calculate the result.
Enter the values you want to compare or calculate, then use the result as a practical reference. The calculator runs in your browser and does not require an account.
This tool also fits into a wider set of practical utilities. Depending on what you are trying to calculate or measure next, you can continue with Days Between Dates Calculator, Date Difference Calculator, Day of the Week Calculator and Days Until a Date Calculator. For the complete collection, visit the utility tools homepage and choose another tool when your task changes.
How to use this calculator
- Enter your values. Select the dates or numbers required by the calculator.
- Check the inputs. Make sure the dates are in the order and range you intend to calculate.
- Calculate the result. The result appears instantly in the calculator above without submitting a form.
- Use the result. Apply the result to your schedule, deadline, planning or date calculation.
How the calculation works
Enter the values you want to compare or calculate, then use the result as a practical reference. The calculator runs in your browser and does not require an account. The calculation is performed locally in your browser, so the page can return a result immediately after you change the inputs.
Things to know about date calculations
Calendar calculations can differ depending on whether a result is treated as an elapsed interval or an inclusive count. This site uses clear calendar-date rules and explains important assumptions where they affect the result. Business-day calculations on this page exclude weekends but do not automatically remove public holidays.
Frequently asked questions
How is age calculated?
Age is calculated from the calendar difference between the date of birth and the selected reference date, accounting for months and days.
Can I calculate age on a specific date?
Yes. You can enter a reference date instead of using today.