How this calculator works
A sphere’s volume grows with the cube of its radius: doubling the radius multiplies the volume by eight. The surface area grows with the square of the radius. At radius 3 the two happen to coincide numerically, since (4/3)π × 27 equals 4π × 9, both being 36π. Negative radii are rejected; zero gives zero.
Formula
V = (4/3)πr³; Surface area = 4πr².
Worked example
A radius of 3 gives V = 36π ≈ 113.097 and surface area 36π ≈ 113.097. A radius of 0.5 gives V ≈ 0.5236 and surface area π ≈ 3.1416.
Advertisement
Frequently asked questions
Can I use the diameter or circumference?
Divide the diameter by 2, or divide the circumference by 2π, to get the radius this calculator needs.
Why do volume and surface area match at radius 3?
It is a coincidence of that one radius: (4/3)r³ equals 4r² exactly when r is 3, so both formulas evaluate to 36π.
How do I find the volume of a hollow ball?
The result is the solid interior. For a shell, subtract the inner sphere volume from the outer one; wall thickness is not an input here.