Proton mass: mass of a nucleon

protonMass is the rest mass of a proton, commonly used in atomic, nuclear, and particle calculations. It is close to, but not equal to, the neutronMass and far larger than the electronMass.

Use and caveats

Use it in SI mass calculations or convert through speedOfLight for rest energy. Atomic mass includes binding effects, so do not replace it blindly with atomicMass.