An Escape Velocity Calculator
Escape velocity is the speed at which an object's kinetic energy exactly cancels the gravity holding it down, and it depends only on the body you are leaving.
Escape velocity
11,180.2961
- Escape velocity in km/h
- 40,249.0658
- Escape velocity in km/s
- 11.1803
- Circular orbital speed
- 7,905.6632
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
v = sqrt(2 x g x r), where g is surface gravity and r is the body's radius
- v
- Escape velocity
- g
- Surface gravity
- r
- Body radius
How to check the result by hand
- 1
Convert the radius to metres
The formula needs metres. A radius quoted in kilometres must be multiplied by 1,000, so Earth's 6,371 km becomes 6,371,000 m.
- 2
Double the surface gravity
Multiply g by two. For Earth that is 9.81 times 2, giving 19.62.
- 3
Multiply by the radius
Multiply the doubled gravity by the radius in metres. This gives 19.62 times 6,371,000, which is about 124,998,000.
- 4
Take the square root
The square root of that product is the escape velocity, 11,180 m/s for Earth, or about 11.18 km/s.
For worked examples, common mistakes and the limits of this formula, read the full How To Calculate An Escape Velocity page.