Earth Curvature Calculator

What Is Earth Curvature Drop?

Over a horizontal distance, the Earth's spherical surface falls away from a straight tangent line. The vertical drop is how far below the tangent the surface sits at the far end. Surveyors, long-range photographers, and radio engineers use this to account for line-of-sight and horizon effects.

Curvature Drop Formula

\(d\) is the horizontal distance in meters and \(R = 6{,}371{,}000\,\text{m}\) is Earth's mean radius. For 10 km (\(d = 10{,}000\,\text{m}\)), the drop is about 7.85 m.

Practical Applications

At sea level, the optical horizon is roughly \(\sqrt{2Rh}\) for observer height \(h\). Over long bridges, laser surveys, or coastal sight lines, curvature drop explains why distant objects appear partially hidden below the horizon.