- 1). Draw the cone on a sheet of paper if it helps you to visualize the problem. Mark the radius and height on your drawing. The radius is the distance from the center of the cone's circular base to its perimeter. The height is measured from the base to the cone's vertex. For example, say the radius is 6 inches and the height is 14 inches.
- 2). Square the radius. You can multiply the radius by itself, which in the example is 6 x 6 = 36 square inches. Alternatively, use the "x squared" key on a calculator. On the Web2.0Calc calculator, enter "6" click on the "x squared" key (fourth row, first column) and press the "=" key to read an answer of 36.
- 3). Multiply your result from Step 2 by pi. In the example, using the Web2.0Calc calculator, click on the "x" key to the right of the number pad, click on the "pi" key (first row, first column) and press "=" to see a result of 113.097 square inches. Alternatively, multiply 36 x 3.14.
- 4). Multiply by the height. In the example, multiply 113.097 square inches x 14 inches = 1,583.36 cubic inches.
- 5). Divide by 3. In the example, 1,583.36/3 = 527.79 cubic inches.
- 6). Check your answer at an online cone calculator. For example, visit the Calculator Free Online Right Circular Cone Calculator. Enter "6" next to "r," enter "14 next to "h," set the "units" drop-down to "inches," click on the "Calculate" button and read the answer of 527.78757 cubic inches, which is the number you calculated, before rounding.
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