The HOUR function in Excel returns a whole number between zero and 23 as an indication of the hour associated with a time value. Zero is the period from 12am - 1am and then increases in whole numbers through to the period from 11pm to 12am which will return 23. The HOUR function "Returns the hour as a number from 0 (12:00AM) to 23 (11:00PM)" The function only requires one argument, a cell or an input that includes a time element. This could be of the format dd/mm/yy hh:mm or just a time reference of hh:mm. In this example, I've created a list of random times which I'll then combine with the HOUR function to return an interfere number that indicates the time associated with the input. The formula is simply =Hour(D2) which I've then filled down to assess the time associated with each value in the range. As you can see from the example, the output of the function is an integer number that varies with each of the times in the source cells.