Set up the area formula. volume = 5 sq ft × 2 ft. volume = 10 cu ft. To calculate cubic feet based upon a square feet figure requires us to know an extra dimension: height/depth. As we know, the volume can be calculated using area and height by multiplying the both, to find cubic footage, simply multiply your square feet by the height in feet. Picture a swimming pool - it could be very long, wide and shallow. The volume in cubic feet is equal to the area in square feet times the height in feet. Since you just need length and width for square footage, eliminate the height and just note the length and width of the surface area. Example: Calculate the cubic feet of a 4 meter high, 8 square foot area. For example, let’s calculate the cubic footage of a 5 square foot area that is 2 feet high. Substitute the actual length and width in the formula. Try our square footage calculator to find the area. You could, in theory, fit many different measurements of square feet into a cubic foot. The formula for cubic feet of a typical square or rectangular object is length multiplied by width multiplied by height. How to Calculate Cubic Feet with Square Feet? Or, it could be shorter in length and width and be very deep.