Age Calculator

Your exact age is computed by subtracting your date of birth from the target date using calendar arithmetic. The calculation accounts for varying month lengths and leap years: first the day difference is computed (borrowing days from the previous month when needed), then the month difference (borrowing 12 months from years when needed), giving a precise count of years, months, and days.

Your total days alive is the difference between the target date and your birth date in milliseconds, divided by the number of milliseconds in a day (86,400,000). This gives an exact count regardless of leap years and daylight saving changes, because the calculation uses UTC midnight timestamps.

The calculator finds your next birthday by taking your birth month and day and projecting them onto the current year. If that date has already passed (or is today), it advances to the following year. The number of days until that future date is the difference from the target date, rounded up to the nearest whole day.