Age Calculator

Calculate your exact age in years, months, days, and more. Find out how many days until your next birthday.

This calculator turns a birth date into two different kinds of age. The first is calendar age -- Years, Months, and Days -- built the way people actually count it: it starts from the raw difference between today's year, month, and day and the birth year, month, and day, then borrows from the next-higher unit whenever a component goes negative (lines 19-27). If today's day-of-month is earlier than your birth day-of-month, it borrows a month and adds that month's real length (28-31 days, not a flat 30) to the day count; if the month difference is then negative, it borrows a year. The second kind is elapsed time: Total Days Alive is the literal number of days between your birth date and this instant, and Total Weeks Alive and Total Hours Alive are just that figure divided or multiplied (lines 29-30 and 32) -- they are not built from the calendar-age figure at all, so the two views can round differently at the edges. Birth Year has by far the largest effect on Age (Years) of the three inputs, since it sets which calendar year is being subtracted from the current one; Birth Month and Birth Day barely move it, only mattering in the handful of days each year when this year's birthday hasn't happened yet. Days Until Next Birthday works the opposite way: it depends only on Birth Month and Birth Day, never Birth Year, since your birthday lands on the same month and day every year regardless of which year you were born (lines 35-41). If this year's birthday has already passed, the calculator rolls the target forward to next year before measuring the gap. It does not adjust for time zones -- all calculations use the server or browser's local calendar date -- and it does not special-case a February 29 birthday in a non-leap year.