Sphere surface area calculator
Calculate a sphere’s surface area from its radius using 4πr². Includes a worked example and square-unit results.
Enter a positive radius. If you know the diameter, divide it by two before entering the value.
Result
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How to use this calculator
Enter a positive radius. If you know the diameter, divide it by two before entering the value.
Formula and method
S=4πr². A sphere’s surface area is four times the area of its great circle.
Worked example
A radius of 3 gives a surface area of 36π≈113.097335529 square units. A diameter of 6 gives the same radius.
Limits and interpretation
This is the external area of a whole sphere, not its volume or a hemisphere’s area. Radius units become squared units.
Frequently asked questions
How should I interpret the result?
A radius of 3 gives a surface area of 36π≈113.097335529 square units. A diameter of 6 gives the same radius.
What inputs and assumptions are required?
This is the external area of a whole sphere, not its volume or a hemisphere’s area. Radius units become squared units.