What is the classical electron radius?

The classical electron radius is r_e = 2.8179403262e-15 m (uncertainty ±1.3e-24), about 2.82 femtometres.

Key facts

Frequently asked questions

What is the value of the classical electron radius?

r_e = 2.8179403262e-15 m, about 2.82 fm, derived by equating electrostatic self-energy to the electron rest energy.

Is the classical electron radius the actual size of an electron?

No. The electron is treated as point-like; r_e is a useful classical scale, e.g. in the Thomson cross section.

How is r_e defined?

r_e = e^2/(4πε₀·m_e·c^2), combining charge, permittivity, electron mass, and the speed of light.

Related pages

• Speed of light
• Planck constant
• Reduced Planck constant
• Avogadro constant
• Boltzmann constant
• Molar gas constant
• Elementary charge
• Gravitational constant

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