Age Difference Calculator

The earlier birth date is identified, then completed years, months and remaining days are counted on the calendar (no dividing by 365 or 365.25). If the earlier day does not exist in a month, that month’s last day counts — so January 31 to February 28 is 1 month, and February 29 reaches its anniversary on February 28 in common years. Total days are the elapsed difference between dates. The optional percentage compares full gap years with the younger person’s completed years as of today; it changes over time and is not a measure of compatibility.

The gap is fixed regardless of who is entered first; equal dates have no older person. Other tools may treat month ends or February 29 differently (for example, using March 1); total days are unambiguous. Dates are plain calendar dates — birth times and time zones are not included. Reset clears both dates.