Escape Velocity Calculator
Find the speed needed to break free of a body's gravity from its mass and radius.
Escape velocity is how fast you'd need to launch — with no further push — to break free of a body's gravity for good. It grows with the object's mass and shrinks the farther out you start. Earth's comes out to about 11.2 km/s.
How it works
Escape velocity is the speed at which an object, given one push and no engine afterward, can coast away from a planet or moon forever without falling back. It's the threshold between orbiting and truly leaving.
The formula is v = √(2GM/r), where G is the gravitational constant (6.674 × 10⁻¹¹), M is the body's mass in kilograms, and r is its radius in meters. Bigger mass raises the bar; starting farther from the center lowers it.
Pick a preset for Earth, the Moon, or Mars to auto-fill realistic numbers, or type your own. Earth works out to about 11.2 km/s — roughly 25,000 mph — which is why rockets have to work so hard.
Frequently asked questions
What is Earth's escape velocity?
About 11.2 kilometers per second, or roughly 11,186 m/s. That's the minimum coasting speed to leave Earth's gravity entirely, ignoring air resistance.
Why is the Moon's escape velocity so much lower?
The Moon has far less mass, so its gravity is weaker and the escape speed is only about 2.4 km/s. That's part of why the Apollo lunar module could lift off with such a small engine.
Does escape velocity depend on the launched object's mass?
No. The formula has no term for the escaping object's mass, so a pebble and a spaceship need the same speed to escape. What differs is the energy required to reach that speed.