Geometry
Surface area of a sphere
Four great circles. The radius must be squared, and the result is in square units.
The Formula
A = 4 x pi x r^2
Four great circles. The radius must be squared, and the result is in square units.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| A | Surface area | square metres | Total area of the curved surface. |
| r | Radius | metres | Centre to surface distance. |
What Each Symbol Means
Asquare metres
Surface area
Total area of the curved surface.
rmetres
Radius
Centre to surface distance.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate the surface area of a sphere page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate The Surface Area Of A Sphere, filed under Math. Every number the guide produces comes from substituting into this one line.