Age Calculator

An Age Calculator works out exactly how old someone is from their date of birth, expressed in years, months, and days rather than a single rounded number. Most people know their age in years, but there are many situations where the precise figure matters: job applications with strict age limits, school and university admissions, passport and visa forms, insurance quotes, pension eligibility, sports age categories, and legal documents that hinge on an exact date.

Calculating this by hand is deceptively easy to get wrong because months have different lengths and leap years add an extra day every four years. Counting back from today across those irregular boundaries produces errors surprisingly often. This calculator handles the calendar arithmetic for you and also shows your age expressed in total months, weeks, days, and even hours, which is useful for milestone tracking and for forms that ask for age as of a specific future date.

The calculator compares two calendar dates rather than simply dividing a number of days by 365. It starts by subtracting the birth year from the target year to get a provisional age in years. It then checks the month and day. If the target date falls before the birthday in that year, one year is subtracted and the remaining months are counted forward from the birth month, borrowing days from the previous month where needed.

Leap years are handled automatically. February gains a twenty ninth day in years divisible by four, except century years that are not divisible by four hundred. Because the calculation walks the real calendar instead of using an average year length, the result stays accurate across any span of dates, including births on 29 February, which are conventionally treated as 28 February in non leap years for age purposes.