Physics
Surface gravity determines how much you would weigh on another world.
Surface gravity is the acceleration a body's mass produces at its surface. It sets how heavy you feel. On the Moon, surface gravity is about 1/6 of Earth's, so you would weigh six times less.
Surface gravity comes from Newton's law of gravitation applied at a body's surface. It scales with mass and inversely with the square of the radius.
Gas giants like Jupiter technically have no solid surface, so their 'surface' gravity is defined at the level where atmospheric pressure equals 1 bar.
g = G·M ÷ r² (G is the gravitational constant, M the mass, r the radius)Mars has ~0.38 of Earth's surface gravity. A 70 kg person on Earth would weigh about 26.6 kg-equivalent on Mars.
Yes — your mass stays the same, but the gravitational force pulling you down is lower, so a scale would read about 38% of your Earth weight.