Date Calculator provides a number of useful date features. Use the Convert feature to convert a short date (i.e. 13/12/1825) to a long date (i.e. Tuesday, 13 December 1825). Use the Calculate feature to calculate the difference between two dates in days, weekdays, weeks, fortnights, months and years. Learn what day you were born and exactly how long ago it was! NOTE: All calculations in this version are based on the Gregorian calendar.