If the diameter is known then divide the diameter by 2 to get the radius. To get proper results use one unit consistently throughout the whole computation. Find the volume of the cylinder using the formula pr²h.
Keep in mind that inches are smaller units so there will be fewer cubic feet than cubic inches.
R cylinder radius h cylinder height To calculate the volume of a cylinder we need to know the radius of the circular cross-section of the cylinder - this is the measurement from the centre of the circle to the outer-edge. Cylinder volume p radius² height. Divide both sides by one of the sides to get the ratio in its simplest form. Find the volume of your object in cubic feet.