Planet Surface Gravity Calculator

Surface gravity of a planet

Surface gravity follows g = GM/r², where G = 6.674·10⁻¹¹ N·m²/kg², M is the mass and r is the equatorial radius. A few reference points: Earth 9.81 m/s², Moon 1.62, Mars 3.71, Jupiter 24.79, Sun 274 m/s². Drop a 70 kg person onto each and they weigh roughly 257 N on Mars, 113 N on the Moon, and 1,735 N on Jupiter. What drives the wild contrast is how mass and radius play off each other. Jupiter packs 318 Earth masses, yet its radius is about 11× ours, so g ends up only around 2.5× what we feel.

Applications

Engineers lean on it to size landers and ascent vehicles for Apollo and the Artemis program. It also sets astronaut exercise loads on the ISS and future Mars missions, feeds ballistic trajectory studies on other bodies, and even keeps fiction honest — Andy Weir's The Martian runs on g_Mars = 3.71 m/s² for its habitat structural loads and rover dynamics.

FAQ

Why is Jupiter's gravity not far larger if it is so massive? Because g scales as M/r², and Jupiter's radius is about 11× Earth's. That r² sitting in the denominator eats away much of the extra mass.

Does g vary across a single planet? It does. On Earth, g runs from about 9.78 at the equator to about 9.83 at the poles, thanks to rotation and the planet's slight bulge, with small local gravity anomalies on top of that.

Is g on the Sun's surface even meaningful? The 274 m/s² figure refers to the photosphere. The Sun has no solid surface, but the value still pins down escape velocity and the conditions under which the stellar wind launches.