Find completed years
Subtract the birth year from the selected year, then subtract one if the birthday has not yet occurred in that selected year. Someone born August 10, 1990 is 36 on October 23, 2026.
Age on a Date Calculator
Find someone’s age in completed years on a date you select, plus the total number of calendar days between the dates.
Age on a Date Calculator
Free · No signupUNDERSTAND YOUR ANSWER
How to use this calculator
Use a selected date instead of today
Enter an event date, a past date, or another future date. The answer is tied to that date, not your device’s current date. A selected date before the birth date is rejected.
Know the leap-day convention
For a February 29 birth, this calculator treats February 28 as the anniversary in a non-leap year. Different institutions may use a different convention. The calendar-day total still counts actual dates, including any February 29 within the interval.
Interpret the day total
Total days is the number of elapsed calendar days from birth to the selected date. It does not include a time of birth or time zone, and it is not a legal age or eligibility determination. Use the completed-year result for everyday reference.
A LITTLE MORE CLARITY
Common questions
Does the result include months and days of age?
This tool reports completed years and total elapsed calendar days. It avoids ambiguous month-length borrowing.
Is my birth date stored?
The tool calculates locally in your browser and does not submit the dates you enter. Clearing or leaving the page removes the form state.
About this tool
Created by Marchelle Cook at Roof & Ratio. These calculations run in your browser; entered values are not uploaded or saved by the calculator. Report a calculation issue with an example so we can review it.
Guide updated October 23, 2026. Displayed decimal results may be rounded; exact fraction and integer results are identified in the answer.