To calculate the volume of a sphere, the following formula is used, where V = volume and r = radius:

Notice that the 4/3 fraction and pi are numerical constants. That means that the formula can be simplified to approximately the following:

## Calculating a Sphere’s Radius from Volume

By rearranging the formula for a sphere’s volume, it is possible to find the radius of a sphere with a known volume. The following is the formula used to calculate the radius of a sphere:

Again, the 3, 4, and pi are constants. The formula for a sphere’s radius can be simplified using the following approximate formula: