Calculate age on a particular date
Use Date of birth for the birth date and Age as of for the reference date. This is useful when you need completed years on an application date or another specified date rather than today.
The result includes complete years, days since the last birthday and total days. It does not display an age in months and days. February 29 birthdays use February 28 in non-leap years under this tool’s convention.
What is this calculator?
Calculate completed years of age, days since the last birthday and total days between birth and a reference date.
What can you use it for?
Use it for practical planning, conversions, measurement or checking the result described here. Calculate completed years of age, days since the last birthday and total days between birth and a reference date.
How to use it
- Enter date of birth.
- Enter age as of.
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
Only completed years are counted. Leap-day birthdays are treated as February 28 in years without February 29.
Worked example
Date of birth: 2000-01-01, Age as of: 2026-10-08. The result is 26 years (completed years of age).
Assumptions and limits
Use the units and formats shown in the input labels. Actual conditions and applicable standards may differ from this simplified calculation.
Frequently asked questions
Does the calculator account for leap years?
It uses calendar dates and reports completed years, days since the last birthday and total days. For a February 29 birth, the birthday is treated as February 28 in a non-leap year.
Can I calculate age on a future date?
Yes. Set the reference date to the date you need. The birth date must not be after the reference date.
What inputs does the Age Calculator need?
Use date of birth, age as of. Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the Age Calculator?
Use the units and formats shown in the input labels. Actual conditions and applicable standards may differ from this simplified calculation.