Convert Inch (in) to Electron Radius (re) instantly.
About these units
Inch (in)
An inch is defined as exactly 25.4 millimeters, a precise metric-based definition that preserves its usefulness within imperial systems. Historically, the inch was based on the width of three barleycorns placed end-to-end, a charming relic of medieval measurement practices. Today, the inch is vital in manufacturing, woodworking, consumer electronics (e.g., screen sizes), and tooling standards across the US and partially in the UK. Its size is small enough to offer usable precision yet large enough to avoid unwieldy fractions for many everyday objects. Even in predominantly metric industries, certain products—such as plumbing parts, bicycle rims, and camera mounts—retain inch-based standards for compatibility. This persistence shows how technological ecosystems can outlive their measurement origins.
Electron Radius (re)
The classical electron radius, approximately 2.818 × 10⁻¹⁵ meters, is a theoretical value derived from classical electromagnetic theory rather than an actual measured size. It represents the radius a charged sphere would need to have in order for its electrostatic self-energy to equal the electron's rest energy. Although electrons are now understood to be point-like or extremely small compared to this radius, the classical electron radius remains useful in scattering theory, especially in calculations involving Thomson scattering — the elastic scattering of electromagnetic radiation by free electrons. Thus, while not a physical dimension of the electron, the classical radius serves as a meaningful parameter in specific areas of physics and retains importance in radiation modeling and plasma physics.