How to Calculate Days by Subtracting Two Dates in Excel

1. Launch Microsoft Excel and open a new worksheet. Type the date in one cell. For example, type '1/1/2010' in cell A1.
2. Type your first date in cell A1. For example, input the date '1/1/2010.'
3. Type your second date in cell B1. For example, input the date '3/14/2011.'
4. Select the cell C1, type '=' and click the date in cell B1. Then type '-', click the first date and press 'Enter.' Cell C1 now shows 438, the number of days between the two dates you input.