About the Escape Velocity Calculator
Escape velocity is the speed an object needs to break free from the pull of a planet, moon or star without any further push. It depends only on the mass and the radius of the body, not on the mass of the object that escapes. This calculator has the main bodies of the solar system built in, and lets you enter any mass and radius of your own. Type the body, or its mass and radius and the escape velocity appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the Escape Velocity Calculator
- 1Enter the body, or its mass and radius.
- 2Pick the units or options from the menus if the escape velocity tool offers them.
- 3Read the escape velocity in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the escape velocity
Science fans, writers and students use it to understand why rockets are so large, why the Moon has almost no atmosphere and why the giant planets keep their gases. It also shows how small a body can be before it cannot hold a lift-off.
A rocket does not have to reach escape velocity at once; it can climb slowly if it keeps burning, but the figure shows the energy needed. Orbiting needs less speed, about 7.9 km/s at Earth's surface, and escaping needs 41 percent more.
How the escape velocity is worked out
Escape velocity = √(2 × G × M ÷ r), where G = 6.6743 × 10⁻¹¹ N·m²/kg², M is the mass of the body and r is the distance from its centre. From the surface of Earth the escape velocity is 11.19 km/s, about 40,270 km/h. For the Moon it is 2.38 km/s, for Mars 5.03 km/s, and for the Sun's surface it is 617.8 km/s.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- Seven bodies built in
- Custom mass and radius
- km/s, km/h and mph
Mistakes to avoid with escape velocity
The result is for the surface, measured from the centre of the body. At higher altitudes the escape speed is lower. The figure also ignores the atmosphere, which would slow a fast projectile at low height.
On phone and computer
On a phone, type into the boxes one after another and read the escape velocity underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the escape velocity move. The escape velocity calculator works the same on both. Space numbers connect. Use Orbital Period Calculator for circling bodies, Gravitational Force Calculator for the pull, Weight on Other Planets Calculator for surface weight, and Speed Calculator for conversions.
Features
- Independent of the object's mass
- √2 times orbital speed
- Measured from the centre
- Clear messages when the escape velocity inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate escape velocity?
Escape velocity = √(2 × G × M ÷ r), where G = 6.6743 × 10⁻¹¹ N·m²/kg², M is the mass of the body and r is the distance from its centre. From the surface of Earth the escape velocity is 11.19 km/s, about 40,270 km/h. For the Moon it is 2.38 km/s, for Mars 5.03 km/s, and for the Sun's surface it is 617.8 km/s.
What is the formula for escape velocity?
Escape velocity = √(2 × G × M ÷ r), where G = 6.6743 × 10⁻¹¹ N·m²/kg², M is the mass of the body and r is the distance from its centre. The escape velocity calculator applies it exactly and rounds only the displayed answer to six significant figures.
Does escape velocity depend on the object's mass?
No. A grain of sand and a spaceship need the same speed (ignoring the push of an engine).
Why is the Moon's number so low?
Its mass is small and its radius is small, so its gravity is weak: about one sixth of Earth's.
What is the relation to orbital speed?
Escape velocity is √2, about 1.41 times, the speed of a circular orbit at the same distance.
Is this escape velocity calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.