Cal2Num calculates the difference between two dates in number of days.

Select your desired reference date using one of the presets, or pick your own custom reference date. Then spin the wheel to pick a compare date and calculate the elapsed number of days. You can also type in the number of elapsed days to calculate the date, which will be shown on the wheel.

You can use this tool to calculate the length of days between any two dates. It can also be useful for calculating date values for operating systems or programming languages, such as Unix or SAS, that represent dates as the elapsed time since a reference date.