Radius input
Radius is the distance from the center of the sphere to its surface. Diameter is twice the radius.
Example
For a sphere with radius 5, surface area is 4 x pi x 25, or about 314.16 square units.
How to use the result
Surface area is useful for estimating coating, covering or exposure on a sphere. Volume is the better measure when you need capacity or the amount of space inside.
Limitations
The formula assumes a perfect sphere. Real objects such as tanks, domes or balls may have seams, flattened areas or fittings that change the usable surface.
Last reviewed: 2026-05-17