Electron Mass Energy

The electron's rest mass stated as an energy — 0.511 MeV, the unit of gamma-ray and pair physics.

Specifications & Metrics

symbol

mec²

status

Measured — CODATA 2022 adjustment

value

0.51099895069 ± 1.6 × 10⁻¹⁰ MeV

Relative Scale in Constants

Core Principles & Analysis

• Pair production needs two of these: 1.022 MeV minimum photon energy.
• Electron–positron annihilation is the cleanest matter-to-energy conversion known.
• Beta-decay spectra are measured against this scale.