Space · Gravity
Escape velocity calculator.
Pick a world or enter a mass and radius to see how fast you must travel to escape its gravity.
Inputs
Escape velocity
Enter mass and radius.
How escape velocity is calculated
Escape velocity is the speed at which an object's kinetic energy equals the energy needed to climb out of a body's gravity, ignoring air drag: v = √(2GM / r). G is 6.6743 x 10-11 m³ kg-1 s-2 (CODATA), M is the body's mass and r is the distance from its centre. It does not depend on the mass of the escaping object.
Worked example. Earth: M = 5.97 x 1024 kg, r = 6378 km. v = √(2 × 6.6743 x 10-11 × 5.97 x 1024 / 6,378,000) = 11.18 km/s (40,241 km/h). NASA lists 11.2 km/s. The Moon gives 2.38 km/s (NASA: 2.4) and Jupiter at the 1 bar level 59.5 km/s (NASA: 59.5).
The speed is for leaving from the surface with no further propulsion. Rockets do not need to reach it at once because they keep thrusting, and it is lower the further from the centre you start.
Frequently asked questions
What is the escape velocity of Earth?
About 11.2 km/s, roughly 40,241 km/h. NASA lists 11.2 km/s.
Does escape velocity depend on the object’s mass?
No. A feather and a spacecraft need the same speed in the ideal case, ignoring air.
Is escape velocity the same as orbital velocity?
No. Escape velocity is the square root of 2 (about 1.41) times the circular orbital speed at the same distance.
Why does the result differ slightly from NASA’s numbers?
NASA’s fact sheet masses are rounded to three significant figures, and gas-giant values are taken at the 1 bar level. The gravity cell is GM/r² and ignores rotation; NASA’s listed gravities include rotation, so they are lower for fast-spinning gas giants (Jupiter 23.1 m/s² against about 24.8 here).
Sources
Checked
- NIST CODATA: Newtonian constant of gravitation
- NASA NSSDCA: Planetary Fact Sheet (metric)
- NASA NSSDCA: Moon Fact Sheet
- NASA NSSDCA: Sun Fact Sheet
- NASA NSSDCA: Pluto Fact Sheet
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Scope
Ideal escape speed from a body’s surface, ignoring air drag, rotation and other bodies. It is not a spaceflight planning tool.