Circle Formulas

For a circle, sphere and cylinder calculator click here.
For a right circular cone calculator click here.

Circumference   =   2 • π • radius   =   π • diameter

Circle Area   =       π • r²     =     ¼ • π • d²

Sphere Formulas

Sphere Surface Area     =     4 • π • r²     =     π • d²

Sphere Volume   =   4/3 • π • r³     =     ( π •d³)/6

Click here or here for partially-filled sphere calculators.

Cylinder Formulas

Surface Area = (2 • π • r²) + (2 • π • r • height)

Where (2 • π • r²) is the surface area of the “ends” and (2 • π • r • height) is the lateral area (the area of the “side”).

Volume   =   π • r² • height   =   ¼ • π • d² • height

If you need a cylinder calculator click here.