Escape Velocity Calculator
The speed needed to break free of a world's gravity, from its mass and radius — in Earth units, so any planet works.
- Escape velocity (km/s)11.19
- Escape velocity (km/h)40,270
- Compared with Earth100%
Inputs used
- Mass (Earth = 1)1
- Radius (Earth = 1)1
About this calculator
Escape velocity is the speed at which an object's kinetic energy exactly matches the gravitational energy holding it down: v = √(2GM/r). Launch faster than that (ignoring air resistance) and you never fall back.
Entering mass and radius as multiples of Earth's makes the formula friendly: Earth itself (1, 1) gives 11.19 km/s. The Moon (0.0123 Earth masses, 0.273 Earth radii) needs just 2.4 km/s — why a small ascent stage could lift Apollo crews home. Mars (0.107, 0.532) needs 5.0 km/s, and Jupiter (317.8, 10.97) a brutal 60.2 km/s. It also works for exoplanets straight from discovery papers, which usually quote both values in Earth units.
Note that rockets don't actually need to hit this speed instantly — they thrust continuously — but escape velocity still sets the energy bill for leaving, which is why launching from Earth is expensive and launching from the Moon is easy.
Frequently asked questions
What is Earth's escape velocity?
About 11.19 km/s, or roughly 40,270 km/h — around 33 times the speed of sound. That's the speed a projectile at the surface would need to coast away from Earth forever without further thrust.
Why is the Moon so much easier to launch from?
With 1.2% of Earth's mass in a body a quarter the size, the Moon's escape velocity is only 2.38 km/s — about a fifth of Earth's. Since fuel needs grow drastically with target speed, leaving the Moon took a lander-top ascent engine rather than a 100-metre rocket.
Does escape velocity depend on the object's mass?
No — a feather and a battleship need the same speed. The object's mass appears on both sides of the energy balance and cancels; only the world's mass and radius (and your distance from its centre) matter.
Results are informational only — not financial, medical or legal advice.