Work out planetary gravity instantly with clear inputs, formula shown and shareable results.
Surface gravity is GM/R^2, so it depends on mass and radius together rather than mass alone. Mars, at 0.107 Earth masses but only 0.532 Earth radii, has 3.71 m/s2 - 38% of Earth's - and an escape velocity of 5.0 km/s. That low escape velocity is why Mars lost most of its atmosphere.
Surface gravity
g = G M / R^2
Escape velocity
v = sqrt(2 G M / R)
Because its radius is also much smaller, and the inverse square on radius partly compensates for the lower mass.
Venus, at 8.87 m/s2 or 90% of Earth's, thanks to a similar mass and radius.