Date & Everyday
Age Calculator
Calculate completed years of age between a date of birth and a target date.
How to use the age calculator
Calculate completed years of age between a date of birth and a target date. Enter the requested values and select Calculate result. Check the units and options before interpreting the answer.
Formula and calculation method
Completed age is calendar-year difference adjusted if the birthday has not yet occurred.
Worked example
Enter birth date and target date to calculate age on that day.
Limitations and interpretation
Results depend on inputs, assumptions and rounding. Verify results before using them for consequential decisions. Health estimates are not medical diagnoses.
Frequently asked questions
Can I calculate age on a past date?
Yes, if it is on or after the birth date.
How is 29 February handled?
The anniversary is treated as 28 February in non-leap years.