How to get the concrete estimate out

> First we need to find out the concrete work volume Hold on, Length = 40 feet Width = 20 feet Thinness = 5 inches Wet volume = (40 * 20 * 5/12) or 333.33 cubic feet [To split in inches to be shared by 12] > Wet size will be multiplied by 1.55 times to get wet size. Dry size = (333.33 * 1.55) or 516.66 cubic feet > Now the sum of the concrete mixing ratio is to be found. Hold on, Ratio = 1: 2: 4 Sum = (1 + 2 + 4) or 7