Age Calculator

An age calculator works out exactly how old someone is from their date of birth — not just in years, but in months, weeks, and days. Enter a birth date and, optionally, the date you want the age measured on, and you get a precise breakdown instantly. It is the fast way to answer “how old am I?” without counting on your fingers or fighting with a calendar.

Calculating age by hand is deceptively tricky because months have different lengths and leap years add a day every four years. People routinely get it wrong by a day or two. This tool handles month boundaries and leap years correctly, so the result is accurate whether the birth date is last year or eighty years ago.

Because it runs in your browser, the dates you enter are never sent anywhere. It is just as happy calculating your own age as a child's age for a form, a pet's age, or the gap between any two dates.

Your age in years is the number of complete years between your birth date and the target date — you do not turn a year older until your birthday actually passes. The months and days are the remainder after those full years are counted. This calculator subtracts the dates day-by-day, borrowing from months and years the way you would in long subtraction, which is what keeps the days component honest across months of different lengths.

Leap years are the part people forget. February gains a 29th day in years divisible by four (with a century-year exception), so a simple “multiply years by 365” shortcut drifts over time. By working from the real calendar, the totals you see for days and weeks reflect those extra leap days exactly.

The same logic powers a date-difference calculation: because you can set both the start and end date, the tool doubles as a quick way to measure the span between any two events — useful for deadlines, anniversaries, project timelines, and eligibility cut-offs.