Case 1
- Radius
- 5
314.159265
Open with these valuesSphere Surface Area Calculator
314.159265units²
Result: 314.159265 units²Four π times the radius squared — exactly four times the area of the circle you would see looking at the ball. A sphere of radius 5 has 100π, about 314.16 square units. Enter the radius, not the diameter.
Worked examples
How it's calculated
A = 4 × π × r²
- StepMeasure the radius — half the width across the middle.
- StepEnter it in any single length unit.
- ResultRead the area in the square of that unit.
Reference table
| Radius | Exact | Surface area |
|---|---|---|
| 0.5 | π | 3.141593 |
| 1 | 4π | 12.566371 |
| 2 | 16π | 50.265482 |
| 5 | 100π | 314.159265 |
| 10 | 400π | 1256.637061 |
Questions
How do you find the surface area of a sphere?
Square the radius and multiply by 4π. A radius of 5 gives 100π, about 314.16 square units.
Why four times the circle?
The shadow a ball casts is a circle of area πr². The curved skin is exactly four of those — a result Archimedes proved, and the reason the formula has no awkward constant.
How much paint or material do I need?
This area, plus whatever your material wastes on curvature. A flat sheet cannot wrap a sphere without cutting, so allow more than the bare number.
What about a hemisphere?
Half the curved skin is 2πr², but a solid half-ball also has a flat circular face of πr², giving 3πr² in total.
Sources and last check
Information, not professional advice.