The fraction 
of a volume filled by a given collection of solids.
Packing Density
See also
Cubic Close Packing, Hexagonal Close Packing, Hypersphere Packing, Kepler Conjecture, Kepler Problem, Packing, Sphere PackingExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Packing Density." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/PackingDensity.html