I have an Excel sheet that's calculating the difference between two times. Its very simple calculation that does not go past midnight.

The formula I'm using is =INT((B1-A1)*24)

This seems to work for most of the calculations, but when I use it against a time from 17:00 to 18:00 it will not calculate the difference. If the time is 16:00 to 17:00 it returns 1, If I use 18:00 to 20:00 it will return an answer of two. The input is formatted as time [hh]:mm, the output is formatted as General.

Any help is greatly appreciated.