A common calculation in precast concrete manufacturing is determining the volume of a round block-out in a manhole wall. A round blockout is a hole either cast or cored into the side of a manhole wall. Mathematically, there are several methods to calculate this volume, ranging from a simple geometric formula to the theory-intense calculus method. The complex shape made by the block-out requires the use of upper-level mathematics and/or 3D CAD, which are two of the few means for precisely calculating the volume of the block-out. Even armed with the calculus formula or 3D CAD, a specialized computer program or calculator that can solve integrals will be needed to calculate the final value. They key word in this approach is calculating “precisely”.