Which planet has the strongest gravity?

Jupiter at about 2.53 g, despite being a gas giant. Its enormous mass more than compensates for its large radius.

Does surface gravity affect atmosphere retention?

Yes. Higher gravity (and thus escape velocity) helps a planet hold onto lighter gases. This is why Mars has a thin atmosphere.

The same formula applies. Super-Earths with 5-10 Earth masses and 1.5-2 Earth radii typically have 1.5-3 g.

Calculate the surface gravity of a planet relative to Earth from its mass and radius ratios: g = g_Earth * (M/M_Earth) / (R/R_Earth)^2.

Mass (Earth masses)

M_E

Radius (Earth radii)

R_E

Surface Gravity

9.8067 m/s²

In Earth g1.0000 g

Surface Gravity vs Mass (Earth masses)

g / g_Earth = (M / M_Earth) / (R / R_Earth)²

This avoids needing G and absolute values. Just enter the planet's mass and radius relative to Earth.

Examples: Mars ≈ 0.38 g, Jupiter ≈ 2.53 g, Moon ≈ 0.17 g.

Mars: 0.107 Earth masses, 0.532 Earth radii.