Age Difference Calculator

Calculating Age Differences

Exact vs Approximate

An age difference in years only is an approximation. This calculator gives the exact difference down to days, accounting for leap years and varying month lengths. Two people born on the same date in different years always have an exact whole number difference in years.

Uses

Age difference between siblings, parents and children, couples, or colleagues. Time elapsed since an event — a project start date, anniversary, or historical event. Days until a future date — a deadline, holiday, or birthday.

Leap Years

A year is a leap year if divisible by 4, except for century years which must be divisible by 400. So 2000 was a leap year, but 1900 was not. Anyone born on February 29 has a 'real' birthday only every 4 years — this calculator handles these correctly.