Escape Velocity Calculator
Works out the speed something needs to get away from a planet or star and never fall back.
Escape velocity
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In km/s — km/s
Circular orbit speed at that height —
Gravity at that height — m/s²
Assumes —
The formula
v = √(2GM ÷ r)
At this speed, kinetic energy exactly matches the energy needed to climb out of gravity. It is √2 times the circular orbit speed at the same height, in any direction clear of the body.
What to watch out for
A rocket does not have to reach this speed all at once. It applies to something coasting with no more thrust.
Frequently Asked Questions
What is the escape velocity of Earth?
About 11.2 km/s, or 40,270 km/h.
What is it for the Moon?
About 2.38 km/s, less than a quarter of Earth’s.