What is a protons relative mass?

The relative mass of a proton measures around 1.0073, "relative" here being defined with respect to the Atomic Mass unit (or Dalton), a twelfth the mass of a carbon-12 atom in its ground state. So it's convenient to say a proton or neutron's relative mass is roughly 1 (the neutron being just barely heavier).

The relative mass of a substance is much more convenient to use than the actual mass since it is such a tiny fraction of the everyday units of mass.. the approximate number of protons it would take just to get one gram would be about six hundred thousand billion billion!