Starlight Tools

Escape Velocity Calculator

Earth escape velocity at the surface is 11.186 km/s, about 25,020 mph or 40,270 km/h. Use the calculator below for any mass, radius, altitude, planet, moon, or custom gravitational parameter.

11.186 km/sEarth surface escape speed
25,020 mphSame speed in miles per hour
40,270 km/hSame speed in kilometers per hour

Inputs

Results

Escape velocity (vesc)
–
Circular speed (vcirc) at same radius
–
Extra speed from circular orbit to escape
–
Relationship
vesc = √2 · vcirc
Gravitational acceleration (g) at radius
–
Radius from center
–
Specific escape energy
–
Inverse result (if target set)
Enter a target escape velocity to compute required altitude.

Escape Velocity Formula

Escape velocity is the ideal speed a coasting object needs so its total mechanical energy reaches zero instead of remaining gravitationally bound. With mass input, the calculator uses:

vesc = √(2GM / r)     with   r = R + h

With the advanced μ input, it uses the equivalent form vesc = √(2μ / r). Circular orbital speed at the same radius is vcirc = √(μ / r), so escape speed is always √2 times circular speed in this ideal model.

Worked example: Earth surface

  1. Use G = 6.67430 × 10-11 m³/(kg·s²), M = 5.9722 × 1024 kg, and R = 6,371,000 m.
  2. Set altitude h = 0, so r = 6,371,000 m.
  3. Compute v = √(2GM/r) = √(2 × 6.67430e-11 × 5.9722e24 / 6,371,000).
  4. The result is about 11,186 m/s, or 11.186 km/s.
  5. Convert to miles per hour: 11.186 km/s × 2,236.936 ≈ 25,020 mph.

Worked example: 400 km above Earth

  1. Use the same Earth mass and G, but add altitude: r = 6,371,000 m + 400,000 m = 6,771,000 m.
  2. Compute v = √(2GM/r) with the larger radius from Earth's center.
  3. The ideal escape speed is about 10.85 km/s, or 24,270 mph.
  4. The circular speed there is about 7.67 km/s, so the extra speed from circular orbit to escape is about 3.18 km/s.

Solar System Escape Velocity Comparison

Sort the table or load any preset into the calculator.

Use
Earth6,371 km398,600.4 km³/s²9.82 m/s²11.18625,023
Mercury2,439.7 km22,031.9 km³/s²3.702 m/s²4.259,507
Venus6,051.8 km324,858.6 km³/s²8.87 m/s²10.36123,178
Moon1,737.4 km4,902.8 km³/s²1.624 m/s²2.3765,314
Mars3,389.5 km42,828.4 km³/s²3.728 m/s²5.02711,245
Ceres473 km62.628 km³/s²0.28 m/s²0.5151,151
Jupiter69,911 km126,686,534 km³/s²25.92 m/s²60.202134,667
Io1,821.6 km5,959.9 km³/s²1.796 m/s²2.5585,722
Europa1,560.8 km3,202.7 km³/s²1.315 m/s²2.0264,532
Ganymede2,634.1 km9,887.8 km³/s²1.425 m/s²2.746,129
Callisto2,410.3 km7,179.3 km³/s²1.236 m/s²2.4415,460
Saturn58,232 km37,931,207.8 km³/s²11.186 m/s²36.09480,740
Titan2,574.7 km8,978.1 km³/s²1.354 m/s²2.6415,907
Uranus25,362 km5,793,939 km³/s²9.008 m/s²21.37547,815
Neptune24,622 km6,836,529 km³/s²11.277 m/s²23.56552,714
Triton1,353.4 km1,427.6 km³/s²0.779 m/s²1.4523,249
Pluto1,188.3 km871 km³/s²0.617 m/s²1.2112,708
Sun695,700 km132,712,440,041.9 km³/s²274.2 m/s²617.6751,381,699

Sources and Constants

Last reviewed for this page: June 23, 2026.

  • G: 6.67430 × 10-11 m³/(kg·s²), CODATA recommended value.
  • Earth μ: 398600.4418 km³/s²; Moon μ: 4902.800066 km³/s²; Mars μ: 42828.375214 km³/s².
  • Preset radii and planetary values: NASA Planetary Fact Sheet and NASA/JPL accepted gravitational parameters.
  • Major moon and dwarf planet values: NASA Solar System Exploration and JPL planetary satellite physical parameters, rounded for classroom calculator use.

Escape Velocity FAQ

What is Earth's escape velocity?

Earth's ideal surface escape velocity is about 11.186 km/s, 25,020 mph, or 40,270 km/h. Real launches also deal with atmosphere, gravity losses, steering, and rotation.

How do I calculate escape velocity?

Use v = √(2GM/r). G is the gravitational constant, M is the central body's mass, and r is distance from the body's center. If you have altitude, use r = mean radius + altitude.

Why does the object's mass not matter?

The object's mass appears in both kinetic energy and gravitational potential energy, then cancels. In the ideal equation, location and the central body's gravity set the speed.

What is the difference between escape velocity and orbital velocity?

Circular orbital velocity keeps an object in a circular orbit at that radius. Escape velocity is √2 times larger and puts the object on an escape trajectory in the ideal two-body model.

Do rockets need to reach escape velocity instantly?

No. A rocket can keep thrusting and adding energy over time. Escape velocity is the speed a coasting object would need at that location without further propulsion.

How does altitude change escape velocity?

Escape velocity decreases as altitude increases because the object starts farther from the body's center. At 400 km above Earth, the ideal value is about 10.85 km/s.

How fast is escape velocity in mph?

For Earth at the surface, it is about 25,020 mph. Use the output selector to show any selected body or custom case in mph, km/s, m/s, or ft/s.

5 Fun Facts about Escape Velocity

Earth gives you a push

Launch eastward near the equator and Earth’s spin hands you ~0.46 km/s of sideways speed—almost 4% of the surface escape velocity for free.

Spin assist

Jumping off asteroids

Small asteroids like Bennu have escape speeds under 0.2 m/s. A gentle hop could launch you into space unless you’re tethered down.

Microgravity

The √2 relationship

No matter the planet, escape speed is always √2 times faster than a circular orbit at the same altitude—so a 3 km/s circular orbit means a 4.24 km/s escape burn.

Elegant math

Energy climbs fast

Kinetic energy scales with v², so doubling escape velocity would need four times the energy per kilogram—one reason super-heavy worlds are so unforgiving.

Energy cost

Black holes obey the rule

The “black” in black hole means the escape velocity at the event horizon exceeds the speed of light, so not even photons can reach infinity.

Extreme limit

Explore more tools