Enter radius or diameter, select a unit, then click Calculate.

A sphere is a perfectly round three-dimensional shape where every point on its surface is equidistant from the center. The radius (r) is the distance from the center to the surface, and the diameter (d) is twice the radius. The volume of a sphere is the amount of space enclosed, calculated as V = 4/3 × π × r³. The surface area is the total area of the sphere's surface, calculated as A = 4 × π × r². The circumference (great circle) is the distance around the sphere through its center, C = 2 × π × r. The cross-section area is the area of a circle formed by cutting the sphere through its center, A_c = π × r². This calculator is essential for geometry, physics, engineering, and everyday applications like calculating tank capacities or ball sizes.

1. Enter either the Radius or the Diameter of the sphere.
2. Select the Unit (meters, centimeters, millimeters, inches, or feet).
3. If you enter one value, the other is automatically calculated.
4. Click Calculate to compute all sphere properties.
5. The result shows volume, surface area, circumference, and cross-section area.
6. Click Reset to restore default example values.