Convert Inch (in) to Earth's Equatorial Radius (R⊕) 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.
Earth's Equatorial Radius (R⊕)
The Earth's equatorial radius is approximately 6,378.1 km. This distance represents the radius measured along the equator, where Earth's rotational bulge makes it slightly larger than the polar radius. Geodesists, cartographers, and astronomers use the equatorial radius for mapping, satellite positioning, and calculating gravitational effects. It is fundamental to defining the shape of the Earth as an oblate spheroid rather than a perfect sphere. Precise knowledge of R⊕ enables accurate navigation, climate modeling, and orbital calculations, forming the basis for modern geodesy and Earth observation systems.