To use Excel's total hour formula, perform the preliminary steps to calculate the time difference between two cells and adjust the cell format to hours, and then use the formula "=INT((B2-A2)*24)", and press Enter. The function INT counts the hours that pass between two times and rounds the total down to the nearest hour.
To calculate the time difference between two cells before calculating the total hours, put the title "In" into cell A1 and "Out" into cell B1. Type the start time into cell A2 and the end time into cell B2, and place the phrase "Total Hours" into cell C1. Click on cell C2, type "=B2-A2" into cell C2, and press the Enter key. This completes the calculation for the time difference between two cells. These cell positions are set for the common Excel spreadsheet; adjust the formulas if you use a spreadsheet that places the cells in different positions.
Alter your cell's format to hours by clicking on the cell and selecting the arrow next to Number in the Home tab. Enter into the custom options, navigate to the Type field, and type the letter "h" into it. This changes the particular cell's format to hours. If you want to change the cell hours directly within the formula, type the formula "=TEXT(B2-A2,"h")".