Escape Velocity Calculator
Compute the theoretical minimum speed an object needs to escape a planet, moon, or asteroid without additional propulsion. Enter the body's mass and radius, and the calculator applies the classical escape velocity formula using the gravitational constant 6.674×10⁻¹¹ N·m²/kg².
Idealized calculation; actual escape speeds vary with conditions.
Examples
- Earth (5.972×10²⁴ kg, 6.371×10⁶ m) ⇒ 11,186 m/s.
- Moon (7.35×10²² kg, 1.737×10⁶ m) ⇒ 2,376 m/s.
- Mars (6.39×10²³ kg, 3.389×10⁶ m) ⇒ 5,027 m/s.
FAQ
What is escape velocity?
The speed needed to break free from a body's gravity without further propulsion.
Does rotation matter?
This simple model ignores planetary rotation and atmosphere.
How do spacecraft actually achieve escape speed?
Rockets accelerate gradually, often using multiple engine burns and gravitational assists. They do not need to reach escape velocity instantly from the launch pad.
Can I enter mass in kilograms and radius in kilometers?
No. Use consistent SI units—convert radius to meters before calculating to avoid incorrect results.
Additional Information
- Escape velocity (vₑ) = √(2GM/R), where G is the gravitational constant, M is mass, and R is radius from the center of mass.
- The result is in meters per second. Divide by 1,000 to express in kilometers per second.
- Values assume an ideal vacuum and do not account for atmospheric drag or rotational boost from the planet's spin.
- Raising altitude increases the radius term, which lowers escape velocity—use the distance from the body's center at your launch point.
- Planning atmospheric ascents too? Cross-check flight phases with the ISO 80000-11 [Mach number guide](/units-and-measures/mach-number-ma-compressibility-and-wave-phenomena/) to respect compressibility limits.
- Need the broader similarity context? Pair those results with the ISO 80000-11 [characteristic numbers overview](/units-and-measures/iso-80000-11-characteristic-numbers/) so Reynolds, Froude, and Weber checks stay aligned.