Measure the dimensions of the space. For rectangular spaces, measure the height, width and depth. For cubes, measure either the height, width or depth. For cylinders, measure the height and the diameter of a circle on one end. For cones, measure the height and the diameter of the base. For pyramids, measure the base and height. For sphere-shaped areas, measure the circumference (all the way around the sphere).
Cube the length of one side of a square prism to find the volume. For instance, if the height is 4 inches, the volume is 64 cubic inches.
Multiply the length by the width by the height to find the cubic space of a rectangular prism. For example, if an object is 4 inches long by 2 inches wide by 1 inch deep, the volume would be 8 cubic inches.
Divide the diameter of the end of a cylinder by two to find the radius. Multiply the radius times itself. Multiply this product by the height and then by 3.14 (pi). For instance, if the diameter is 6 inches, divide this by 2 to get 3. Multiply 3 by itself to get 9. If the height is 20 inches, multiply 9 times 20 to get 180. Then multiply 180 by 3.14 to get a cubic space of 565.2 inches.
Find the cubic space of a cone by dividing the base's diameter by 2 to get the radius. Square the radius and multiply it by the height and then by 3.14. Divide your answer by 3. For example, if your cone has a diameter of 5 inches on its base, divide 5 by 2 to get 2.5. Square this to get 6.25. If the height is 10 inches, multiply 6.25 by 10 to get 62.5. Multiply 62.5 by 3.14 to get 196.25. Divide 196.25 by 3 to get 65.417 cubic inches.
Calculate the cubic volume of a rectangular pyramid by first multiplying the length by the width of the base. Then multiply this figure by the height. Finally, divide by 3 for the volume. For example if the base of a pyramid is 10 inches wide by 10 inches long, multiply 10 by 10 to get 100. Then multiply 100 by 30 if the pyramid is 30 inches tall. The product of 100 times 30 is 3,000. Divide 3,000 by 3 to get a volume of 1,000 cubic inches.
Find the volume of a sphere by first dividing the circumference by 3.14. If the circumference is 30 inches, for example, you would divide 30 by 3.14 to get 9.55. This is the diameter of the shape. Divide the diameter by 2 to get the radius. In this example, the radius would be 4.775. Cube the radius (multiply it times itself three times). Then multiply that product by 3.14. In this case, 4.775 cubed is 108.873. You would then multiply that by 3.14 to get 341.861. Multiply your answer by 4 and then divide by 3. In this example, you would multiply 341.861 times 4 to get 1,367.444. Then divide this by 3 to get 455.815 cubic inches.
Divide your answers in cubic inches by 1,728 if you want to convert to cubic feet.