Convert mass to weight under Earth or any other gravity, and between units.
Weight is the gravitational force on a mass: W = m × g. On Earth, g ≈ 9.807 m/s² (varies slightly with latitude and altitude). On the Moon g ≈ 1.62 m/s², so a 70 kg person weighs about 686 N on Earth but only 113 N on the Moon — though their mass remains 70 kg everywhere.
Weight
Weight (N) = Mass (kg) × Gravitational acceleration (m/s²)
Mars has about 38% of Earth's surface gravity (3.72 m/s² vs 9.81 m/s²). A 70 kg person would weigh about 260 N on Mars compared to 686 N on Earth — less than 40% of their Earth weight.
Mass (kilograms) measures the amount of matter — it's the same everywhere. Weight (Newtons) is the gravitational force on that mass, which varies with the local gravitational acceleration g.
Bathroom scales display mass (kilograms) or kilogram-force (kgf), not scientific Newtons. Because g is approximately constant on Earth's surface, scales are calibrated to divide the force reading by 9.807 and show kg. In physics, weight is always a force in Newtons.
The Sun's surface gravity is 274 m/s² — about 28 times Earth's — because of its enormous mass (333,000 × Earth). However, the Sun has no solid surface; spacecraft encounter the Sun's gravity from orbit, not its surface.