Working out an exact age sounds trivial until you account for leap years and months of different lengths. This calculator does it precisely, and shows your age several different ways.
How age is counted
Age is normally expressed as completed years, months and days. To compute it, we compare the day and month of the reference date against your birth date, borrowing a month or a year when the current day or month is smaller — exactly how you'd do it by hand, but without the arithmetic slips.
Why leap years matter
A common shortcut is to multiply years by 365, but that ignores leap days. Over a long life this adds up to weeks of difference. Counting the real calendar days between two dates is the only accurate approach, and it's what this tool does.
Frequently asked questions
We count the full years between your birth date and the reference date, then the leftover months, then the leftover days — borrowing from months and years where needed, and accounting for leap years and different month lengths.
Because of leap years. Roughly every four years has 366 days, so multiplying years by 365 undercounts. This calculator counts the actual calendar days between the two dates.
Yes. Enter any date in the 'Age at date' field — past or future — to see the age (or time elapsed) on that day.