Whether you are working on a project with numerous tasks or want to keep track of when your bills are due each month, you can set up Excel to calculate due dates for you. Excel is known for its ability to create complex formulas and equations, but you can use the same capability to calculate dates as well. To calculate due dates, you will need to know starting dates.
Open an Excel spreadsheet you will be using to calculate due dates.
Create a column for current dates or starting dates. For example, if you have a number of tasks for which you want to find due dates, enter a heading such as "Start Date" in cell "A1."
Enter your start dates in the rows below your heading. For example, if your first task starts on June 1, 2011, you would enter "6/1/2011" into cell "A2."
Create a second column heading called "Due Date" in column B or next to the first column.
Enter your due date formula in the first empty cell under the "Due Date" heading. Enter an equal sign, then click the cell that has the start date, enter a plus sign and finally, the number of days you want to add. Press "Enter." For example:
In this example, you are adding 30 days to the date in cell "A2." Excel displays "7/1/2011" as the due date.
Copy the due date formula to the other cells in the "Due Date" column to have Excel calculate due dates for all your starting dates using the same number of days.
If your dates are not showing up as dates, select your columns, then click the “Home” tab on the ribbon, then click the down arrow next to “General” in the format number window in the "Number" group. Select “Short Date” or “Long Date” to have Excel display the cell as a date.