Have you ever wanted to know how old you were on a certain date? Or how old you'll be on some date in the future? Are you writing a story and need to know what age a character is on a particular date? Just enter the dates here and click the button that says 'Calculate' to see the answer. These Javascript routines I wrote give the elapsed time in days between any two dates, and if the first date is a birthday, the person's age on the second date.
The logic assumes the Gregorian calendar, so it won't tell you anything useful about dates before 10/15/1582.