Escape velocity calculator
Escape velocity is the lowest speed an object needs to leave a body's gravity without further thrust. Pick a body or enter your own mass and radius.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter body, height above surface, mass (custom body) and radius (custom body).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
v = √(2GM ÷ r), where GM is the gravitational parameter and r is the mean radius plus the height. GM and radius come from the NASA fact sheets.
Example
Inputs: Body = Earth, Height above surface = 0 km. Result: Escape velocity: 11.186 km/s; In metres per second: 11,186 m/s; In kilometres per hour: 40,270 km/h.
Limits and caveats
- Air drag and the body's rotation are ignored, so a real launch needs more speed.
- The mean radius is used; values at the equator or poles differ slightly.
Questions about this tool
What is Earth's escape velocity?
About 11.19 km/s at the surface, roughly 40,270 km/h.
Does escape velocity depend on the rocket's mass?
No. It depends only on the body's mass and the distance from its centre.
Why does escape velocity drop with height?
Gravity weakens farther from the centre, so less energy is needed to escape.