Escape Velocity Calculator
Find the minimum ideal speed needed to escape a spherical body gravity well.
Compute ideal escape speed from mass and radius
Escape velocity is the speed whose kinetic energy equals the gravitational binding energy from a chosen radius to infinity. This calculator evaluates the square root of twice the gravitational constant times body mass divided by center radius. It applies to an ideal spherical mass and provides a compact comparison for planets, moons, asteroids, or hypothetical bodies when mass and radius are known.
Using mass 5.972 times ten to the twenty-fourth kilograms and radius 6.371 million meters gives 11186 meters per second, or about 11.186 kilometers per second. That familiar Earth surface value ignores atmospheric drag and rotation. Because radius is measured from the body's center, entering altitude alone would be incorrect; add altitude to the physical radius first.
Distinguish energy threshold from a flight plan
The result is an instantaneous, unpowered, vacuum energy threshold. A real launch can escape with lower speed at any moment by applying thrust over time, while atmosphere, rotation, other bodies, and changing mass complicate the trajectory. The inputs remain in your browser. Do not treat this two-body idealization as mission guidance or substitute it for numerical orbital analysis.
Frequently Asked Questions
Is escape velocity the same as orbital velocity?
No. At the same radius, ideal escape velocity is the square root of two times circular orbital velocity.
Should radius include altitude?
Yes. Use distance from the body center, so add altitude to the body radius when starting above the surface.
Does a rocket need to reach this speed instantly?
No. Continuous thrust can add energy gradually; escape velocity is the equivalent unpowered vacuum threshold.
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