Escape Velocity Calculator

In short Escape velocity is the speed at which an object's kinetic energy exactly equals the gravitational energy binding it, so it can coast away and never fall back: v = √(2GM/r). From Earth's surface that is 11.186 km/s, or about 40,300 km/h. The circular orbital velocity at the same radius is 7.910 km/s, and the ratio between them is exactly √2 — not approximately. Escaping needs twice the kinetic energy of circling, and energy goes as v², so the speed ratio is the square root of two. The page prints that ratio so you can watch two separate calculations produce one exact relationship. Escape velocity does not depend on the mass of the thing escaping: a pebble and a rocket need the same speed. What differs is the fuel needed to reach it. And no rocket actually launches at this speed — a rocket climbs under continuous thrust and never needs it in one go, which is why the figure matters for asteroid impacts and for whether a planet can hold on to an atmosphere rather than for spaceflight. This page stores only two numbers per body, GM and a mean radius; surface gravity, escape velocity and orbital velocity are all derived, so the table cannot quietly disagree with itself.