List of shapes with known packing constant

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.^[2] Therefore, any such body for which the lattice packing constant was previously known, such as any ellipse, consequently has a known packing constant. In addition to these bodies, the packing constants of hyperspheres in 8 and 24 dimensions are almost exactly known.^[3]

Image	Description	Dimension	Packing constant	Comments
	All shapes that tile space	all	1	By definition
	Circle, Ellipse	2	π/√12 ≈ 0.906900	Proof attributed to Thue[4]
	Smoothed octagon	2	$\eta_{so} = \frac{ 8-4\sqrt{2}-\ln{2} }{2\sqrt{2}-1} \approx 0.902414 \, .$	Reinhardt[5]
	All 2-fold symmetric convex polygons	2		Linear-time (in number of vertices) algorithm given by Mount and Silverman[6]
	Sphere	3	π/√18 ≈ 0.7404805	See Kepler conjecture
	Bi-infinite cylinder	3	π/√12 ≈ 0.906900	Bezdek and Kuperberg[7]
	All shapes contained in a rhombic dodecahedron whose inscribed sphere is contained in the shape	3	Fraction of the volume of the rhombic dodecahedron filled by the shape	Corollary of Kepler conjecture. Examples pictured: rhombicuboctahedron and rhombic enneacontahedron.

References

1. Bezdek, András; Kuperberg, Włodzimierz (2010). "Dense packing of space with various convex solids". arXiv:1008.2398v1 [math.MG].
2. Fejes Tóth, László (1950). "Some packing and covering theorems". Acta Sci. Math. Szeged 12.
3. Cohn, Henry; Kumar, Abhinav (2009). "Optimality and uniqueness of the Leech lattice among lattices". Annals of Mathematics 170 (3): 1003–1050. doi:10.4007/annals.2009.170.1003.
4. Chang, Hai-Chau; Wang, Lih-Chung (2010). "A Simple Proof of Thue's Theorem on Circle Packing". arXiv:1009.4322v1 [math.MG].
5. Reinhardt, Karl (1934). "Über die dichteste gitterförmige Lagerung kongruente Bereiche in der Ebene und eine besondere Art konvexer Kurven". Abh. Math. Sem. Univ. Hamburg 10: 216–230. doi:10.1007/bf02940676.
6. Mount, David M.; Silverman, Ruth (1990). "Packing and covering the plane with translates of a convex polygon". Journal of Algorithms 11 (4): 564–580. doi:10.1016/0196-6774(90)90010-C.
7. Bezdek, András; Kuperberg, Włodzimierz (1990). "Maximum density space packing with congruent circular cylinders of infinite length". Mathematika 37: 74–80. doi:10.1112/s0025579300012808.