In this example and calculator, for both rectangles, enter the number of inches for each width side... Enter the number of inches for the length side; see our default information and graphic below. (Please keep in mind that the width of the number 2 rectangle joins into number 1 vertical length, though not the TOTAL length.) Also enter the number of inches high each side is (8 inches by default); and press the Calculate button. (Each rectangle's height can be different to compensate for sloped ground.) The approximate volume of filling material is in cubic inches, cubic feet and cubic yards for your convenience.