Multiply the volume by 3. For example, suppose the volume of the sphere is 100 cubic units. Multiplying that amount by 3 equals 300.
Divide this figure by 4π. In this example, dividing 300 by 4π gives a quotient of 23.873.
Calculate the cube root of that number. For this example, the cube root of 23.873 equals 2.879. The radius is 2.879 units.