The Mass or Weight of a Sphere calculator computes the mass or weight of a sphere based on the radius (r) and the mean density (ρ).
INSTRUCTIONS: Choose units and enter the following:
Mass of Sphere (m) : The calculator returns the mass of the sphere in kilograms (kg). However, this can be automatically converted to other mass or weight units (e.g., pounds, tons) via the pulldown menu next to the answer. NOTE: To find the mean density (ρ) of many common substances, elements, liquids and materials, CLICK HERE (e.g., the density of water is 1,000 kg/m³).
Common Mean Densities 
Metals

Fluids

The formula for the mass of a sphere:
M = 4/3⋅π⋅r³⋅mD
where:
The mass of a sphere calculator first computes the volume of the sphere based on the radius. With the computed volume, this formula then executes the simple equation below to compute the approximate mass of the object.
See the mean density (ρ) of many common substances
Above the formula for mass and volume of a sphere are combined.
Converting from mass to weight is trivial under the right conditions. Fortunately those conditions are generally true anywhere on the surface of the Earth, so the conversions built into the vCalc unit conversion engine can be assumed to be fairly accurate unless you require weight at very high altitudes or in space.