In the Principia, Isaac Newton imagined a cannon on a mountain so high it stood above the air. Fire it gently and the ball falls back. Fire it harder and it lands further away. Fire it hard enough and the ground curves away beneath it as fast as it falls, and it never comes down. Escape Velocity Calculator draws that thought experiment live, for real worlds and real projectiles, with every orbit worked out on your device.
The figures for the planets, moons and asteroids come from NASA’s Jet Propulsion Laboratory and are sourced on every page. Anything that is still an estimate is marked as one. Nothing is fetched and nothing about you is sent anywhere, because the app never goes online.
Features
- The Cannon — choose a world, a charge and a launch height, fire sideways or straight up, and watch the shot fall back, orbit or escape. The view follows the shot, close in for a ball that barely leaves the barrel and drawing back to the whole world for an orbit
- Famous shots — the Paris Gun from Pluto, a rifle on a neutron star, a jump off Deimos, the HARP gun from the Moon, Newton’s own cannon, a cricket ball off Bennu, Jules Verne’s Columbiad, and a cannon hovering beside a black hole
- Thirty-six worlds — the Sun, every planet, the great moons, Pluto and Ceres, asteroids and a comet, a white dwarf, neutron stars, black holes, and the International Space Station, the Great Pyramid and a Saturn V, most with a painted portrait
- Escape speed, gravity, mass, density and your own weight on every world, which projectiles get away, and how slowly a clock runs near the compact ones
- The Ladder — every world on one scale of escape speed, from a pyramid to a black hole, with every projectile drawn across it
- The Rocket — the rocket equation in its Newtonian and relativistic forms, for any engine from kerosene to a photon rocket, with fuel told in Saturn Vs, Earths, Suns and observable universes
- The Forge — build a world, give it a name and a colour, and squeeze it until it becomes a black hole. The Earth does at 8.87 millimetres
- Saved setups, and a shot shared as a composed card rather than a screenshot
- Speeds in metres or kilometres per second, kilometres or miles per hour, Mach, or a fraction of the speed of light
- Universal — on iPad the world fills the screen and the Bodies list sits beside each world’s page
- No account, no subscription, no adverts, no tracking and no analytics
About the Numbers
The escape speeds the app computes for the planets match the Jet Propulsion Laboratory’s own published values to the hundredth of a kilometre per second they are printed to.
The approximations are stated rather than hidden. Every world is treated as a sphere with no air, so a rifle round that would escape Ceres is shown escaping it, and the app tells you where that matters: air would stop it on Earth, and an irregular asteroid has a different escape speed at every point on its surface. Near a neutron star or a black hole the escape speed still holds in general relativity, and the app says which of its other figures are only approximate there.
Privacy
No ads. No tracking. No analytics. No subscriptions. No in-app purchases. No account.
The app makes no network requests at all and asks for no permissions. Full detail in the privacy policy.
Support
Need help with Escape Velocity Calculator? Whether you have a question, want to request a feature, or need to report a problem:
- Ask a question — get help using the app
- Report a bug — let us know if something isn’t working
- Request a feature — suggest an improvement
You can also browse existing issues to see if your question has already been answered.