This concrete calculator can assist you in determining the amount of bags of QUIKRETE (r) Concrete Mix, Mortar Mix, or Fast-Setting Concrete required for the following projects: (All calculations are rounded to the nearest entire bag.) Use this calculator to determine how much concrete you will need for your project. Enter the number of yards required and then click on the Calculate button. The result will be displayed in the text box below. For example, if you want to make a driveway that is 20 feet long by 8 inches wide, enter 20 into the Length field and 8 into the Width field. Then click the Calculate button. You now know how much concrete you will need.