About the Age Calculator
What is this?
Age calculation seems simple, but precise age — in years, months, and days — requires accounting for leap years and months of different lengths. This calculator gives your exact age from a birth date to any reference date, useful for official forms, eligibility checks, and celebrating milestones.
How it is calculated
Exact age is calculated by subtracting the birth date from the target date. If the day of the target is earlier than the day of birth, a month is "borrowed" (and the days in that month are added), just as in column subtraction. Years are adjusted similarly if the target month is earlier than the birth month.
Reference ranges
Frequently asked questions
How is exact age calculated?
By subtracting the birth date from the target date, borrowing months and days when needed — the same principle as column subtraction in arithmetic. Leap years are handled automatically.
Why does my age change at different times in different cultures?
The Western system increments age on the birthday. Some East Asian traditions increment on the lunar new year, meaning everyone in a given year-group is considered the same age.
Is age calculated from conception or birth?
Legal age is almost universally calculated from birth. Some medical contexts (such as pregnancy) use gestational age, counted from the first day of the last menstrual period.
Age & Date Calculator
Calculate exact age in years, months, and days, or find the number of days between two dates.