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Crown Tools Vault · Free utility

Age & Date Difference Calculator

Calculate an age on a chosen date, or the calendar duration between two dates.

Runs in your browser · No signup

Age on a date

Choose a birth date and the date to calculate age on.

Date difference

Measure the duration from a start date to an end date.

Gregorian calendar, years 0001–9999. Dates are compared without times or daylight-saving shifts. End date must be on or after start date; birth date cannot be after the age-on date. A February 29 anniversary falls on February 28 in a non-leap year. Calendar duration counts whole years, then whole months anchored to the original day of the month, then remaining days. Each anniversary or month candidate clamps to its last valid day. This is a calculation convention, not a legal age determination.