How to Add 12 Weeks to a Date in Excel

1. Open Microsoft Excel.
2. Write the start date in cell A1 using the familiar format month/day/year and press 'Enter.' As an example, to enter January 1, 2010, you would enter '1/1/2010' in cell A1. Alternatively, enter the function '=today()' to enter the current date.
3. Type '=A1 84' in cell B1 and press 'Enter' to calculate the date exactly 12 weeks from the start date. Alternatively, enter '=A1 (7*12)' to break up the number of days in the week times the number of weeks. This allows you to easily change the number of weeks. You can even reference the number of weeks entered in another cell, such as A2, by changing the formula to '=A1 (7*A2).'