The packing constant of a geometric body is the largest average density achieved by packing arrangements of congruent copies of the body.
For most bodies the value of the packing constant is unknown.
[1] The following is a list of bodies in Euclidean spaces whose packing constant is known.
[1] Fejes Tóth proved that in the plane, a point symmetric body has a packing constant that is equal to its translative packing constant and its lattice packing constant.
In addition to these bodies, the packing constants of hyperspheres in 8 and 24 dimensions are almost exactly known.