Proton Mass Energy

The proton's rest energy, 938.272 MeV — the yardstick of nuclear physics.

Specifications & Metrics

symbol

mpc²

status

Measured — CODATA 2022 adjustment

value

938.27208943 ± 2.9 × 10⁻⁷ MeV

Relative Scale in Constants

Core Principles & Analysis

• Almost 99% of it is QCD binding energy, not the three quarks' bare masses.
• Hydrogen fusion converts 0.7% of it to sunlight.
• The mass gap between it and the electron makes chemistry possible at all.