Escape Velocity Calculator

Escape velocity is the minimum launch speed an object needs to break free from a body's gravity and never fall back, ignoring air drag and further propulsion. Reach that speed at the surface and, coasting alone, the object slows forever without stopping.

v = sqrt(2 x G x M / r), where G is the gravitational constant, M is the body's mass and r is the distance from its centre, usually the surface radius. This calculator uses G = 6.674e-11 N m^2/kg^2.

Using the Earth preset (mass 5.972e24 kg, radius 6.371e6 m) the tool returns 11.1857 km/s, or 11185.7 m/s. That matches the familiar textbook figure of about 11.2 km/s.

No. The object's own mass cancels out of the equation, so a pebble and a rocket need the same escape speed from the same point. Only the mass and radius of the body you are leaving matter.

No, not in this idealised form. It is a speed, not a velocity vector, so any direction that clears the surface needs the same magnitude. A planet's spin can give a small real-world assist, but the formula here ignores that.

Mass in kilograms and radius in metres, matching the SI value of G built into the tool. You can type scientific notation such as 1.898e27. The output is shown in km/s and m/s.

Yes. The radius field is simply the distance from the centre, so add your altitude to the surface radius. A larger radius gives a lower escape velocity, since gravity weakens with distance.

The five presets are a convenience for common Solar System bodies, but the tool works for any object. Enter the mass and radius of a dwarf planet, asteroid, exoplanet or a black hole model and it computes the same way.

Yes. Everything runs in your browser with JavaScript, so no mass, radius or result is uploaded to a server. It also keeps working offline once the page has loaded.

Small differences come from the constants. This tool fixes G at 6.674e-11 and uses whatever mass and radius you supply, while references may use G = 6.6743e-11 or a different mean radius, shifting the last digits.