Escape Velocity Calculator
Calculate the minimum speed needed to break free from a planet or moon’s gravity (ignoring atmosphere and rotation).
What Is Escape Velocity?
Escape velocity is the minimum speed an object needs to move away from a celestial body and never fall back, assuming no propulsion after launch and no atmospheric drag. It depends only on the body’s mass and your distance from its center.
For Earth at the surface, this value is about 11.2 km/s. That number sounds huge, but real rockets don’t instantly jump to 11.2 km/s straight up. They accelerate over time, follow curved paths, and deal with air resistance and gravity losses.
How the Formula Works
The Equation
ve = √(2GM/R)
- ve = escape velocity (m/s)
- G = gravitational constant (6.67430 × 10-11 m3 kg-1 s-2)
- M = mass of the body (kg)
- R = distance from center of mass (m)
Mass and Radius Matter Most
Bigger mass increases gravity, so escape velocity rises. Larger radius (for the same mass) spreads that mass out and lowers surface gravity, reducing escape speed.
How to Use This Escape Velocity Calculator
- Select a preset body for instant values, or choose Custom values.
- Enter mass in kilograms and radius in kilometers.
- Click Calculate Escape Velocity.
- Read the result in m/s, km/s, km/h, and mph.
Example Values You Should Expect
- Moon: ~2.38 km/s
- Mars: ~5.03 km/s
- Earth: ~11.19 km/s
- Jupiter: ~59.5 km/s
- Sun (at photosphere): ~617.7 km/s
Important Notes and Limits
Atmosphere Is Ignored
This calculator uses the ideal vacuum formula. In reality, thick atmospheres (like Earth’s) require extra energy due to drag and heating.
Rotation Is Ignored
Launching eastward from a rotating planet gives a free speed boost. Earth’s rotation can reduce required rocket delta-v depending on latitude.
Escape Velocity Is Not “Rocket Requirement”
Rockets are governed by delta-v budgets, staging, engine efficiency, and flight profile. Escape velocity is still a foundational benchmark for gravitational strength.
Why This Matters
Escape velocity appears across astronomy, astrodynamics, and mission design. It helps compare how hard it is to leave different worlds and explains why tiny moons are easier to depart than massive planets.