Escape Velocity Calculator
The Speed That Lets You Outrun Gravity
Escape velocity is the minimum speed an object needs, fired straight up with no further propulsion, to break free of a body's gravity permanently rather than falling back or settling into orbit. It has nothing to do with the object's own mass — a pebble and a spacecraft need the identical speed to escape Earth — and everything to do with the mass and radius of the body being escaped. This calculator computes it exactly for known solar system bodies or for any custom mass and radius.
The Formula
Where G is the gravitational constant (6.674 × 10⁻¹&sup9; m³ kg⁻&sup9; s⁻&sup9;), M is the mass of the body, and r is the distance from its center — typically its surface radius. The calculator uses each body's standard gravitational parameter (GM, the product of G and mass) directly, which is known to much higher precision than G and M measured separately.
Why Escape Velocity Matters
- Launch vehicle design — a rocket's required delta-v budget is built directly on top of the escape velocity of the body it's leaving, plus losses from atmospheric drag and gravity turning.
- Explaining thin atmospheres — the Moon and Mars have weak atmospheres largely because their low escape velocities let even moderately fast gas molecules drift away into space over geological time.
- Comparing worlds — lining up escape velocity across bodies makes clear why leaving Jupiter's gravity well is a fundamentally harder engineering problem than leaving the Moon's.
Escape Velocity by Body
| Body | Escape velocity (km/s) | Escape velocity (m/s) |
|---|---|---|
| Earth | 11.186 | 11,186.1 |
| Moon | 2.376 | 2,376.2 |
| Mars | 5.027 | 5,027.0 |
| Jupiter | 60.202 | 60,201.5 |
Values are computed directly from the calculator's own GM and radius constants using v = √(2GM/r); they match the widely published escape velocity figures for these bodies.
How to Use This Calculator
- Choose a mode: "Select Known Body" for Earth, Moon, Mars, or Jupiter, or "Custom Mass & Radius" for any other body.
- In known-body mode, just pick the body from the dropdown.
- In custom mode, enter the body's mass in kilograms and its radius in meters.
- Select Calculate to get the escape velocity in both m/s and km/s.
Related Calculations
Escape velocity is exactly √2 times the circular orbital speed at the same radius — compare the two directly with the Orbital Velocity Calculator, or see how that same gravity affects surface weight with the Planet Weight Calculator.