Escape Velocity Calculator
Calculate the escape velocity for Earth, Moon, Mars or any custom celestial body. Formula: v = √(2GM/R).
About escape velocity
Escape velocity is the minimum speed an object needs to escape the gravitational pull of a body without further propulsion. It is derived from energy conservation: kinetic energy must equal gravitational potential energy.
M = mass of body (kg)
R = radius of body (m)
Frequently asked questions
What is escape velocity of Earth?
Earth's escape velocity is approximately 11.2 km/s (about 40,320 km/h or 11,200 m/s). This is the speed a rocket must reach to completely leave Earth's gravitational influence, ignoring air resistance and assuming no further thrust after launch.
Does escape velocity depend on the direction of launch?
No — escape velocity is the same in any direction, assuming no air resistance. Whether you launch vertically or at an angle, you need the same speed. In practice, rockets launch eastward to gain boost from Earth's rotation (up to 0.46 km/s at the equator) and at an angle to reach orbital velocity first.
What is the difference between orbital velocity and escape velocity?
Orbital velocity is the speed needed to maintain a circular orbit at a given altitude, while escape velocity is the speed needed to completely leave the gravitational field. Escape velocity is exactly √2 times the circular orbital velocity at the same radius. For Earth at the surface: orbital velocity ≈ 7.9 km/s, escape velocity ≈ 11.2 km/s.
Why can the Moon not hold an atmosphere?
The Moon's escape velocity is only 2.38 km/s. Gas molecules in an atmosphere have thermal speeds that depend on temperature and molecular mass. On the Moon, light molecules like hydrogen and helium, and even heavier ones like nitrogen and oxygen at lunar temperatures, have thermal speeds comparable to the escape velocity and gradually leak into space over geological time.
What is the escape velocity of a black hole?
A black hole is defined by having an escape velocity equal to or greater than the speed of light (c ≈ 3×10⁸ m/s). The boundary at which escape velocity equals c is called the event horizon or Schwarzschild radius: r = 2GM/c². Nothing — not even light — can escape from within the event horizon.