For heavy nuclei, it is close to the nuclear saturation density
nucleons/fm3, which minimizes the energy density of an infinite nuclear matter.
The nuclear density of a typical nucleus can be approximately calculated from the size of the nucleus, which itself can be approximated based on the number of protons and neutrons in it.
The radius of a typical nucleus, in terms of number of nucleons, is
The proton is not a fundamental particle, being composed of quark–gluon matter.
Using deep inelastic scattering, it has been estimated that the "size" of an electron, if it is not a point particle, must be less than 10−17 meters.
[citation needed] This would correspond to a density of roughly 1021 kg/m3.
There are possibilities for still-higher densities when it comes to quark matter.
In the near future, the highest experimentally measurable densities will likely be limited to leptons and quarks.