Weight Calculator

Mass is the amount of matter in an object, measured in kilograms (kg), and stays constant everywhere. Weight is the gravitational force on that mass, measured in Newtons (N). Weight = mass × gravitational acceleration (W = mg). On the Moon, your mass is the same, but your weight is about 1/6 of Earth weight because the Moon's gravity is weaker.

The Moon's gravitational acceleration is only 1.62 m/s², compared to Earth's 9.81 m/s². This is because the Moon is smaller and less massive than Earth. A 70 kg person weighs 686.7 N on Earth but only 113.4 N on the Moon - about 16.5% of their Earth weight.

Mars has a surface gravity of 3.72 m/s², about 38% of Earth's. A 70 kg person would weigh 260.4 N (58.5 lbf) on Mars compared to 686.7 N (154.3 lbf) on Earth. This lower gravity is one reason Mars colonization is appealing - less energy needed to launch from the surface.

Jupiter's surface gravity is 24.79 m/s² (2.53× Earth) because of its enormous mass - 318× Earth's mass. Despite being a gas giant with no solid surface, if you could stand on a platform at Jupiter's cloud tops, you'd weigh 2.5× your Earth weight. A 70 kg person would experience 1735.3 N of force.

Apparent weight is what you feel or what a scale reads, which can differ from true weight. In a rising elevator, apparent weight increases (you feel heavier). In a falling elevator, apparent weight decreases (you feel lighter). In free fall, apparent weight is zero - this is 'weightlessness' astronauts experience in orbit, though they still have weight.

Astronauts in orbit are not beyond Earth's gravity - the ISS experiences about 90% of surface gravity. They're 'weightless' because they're in free fall around Earth. Their spacecraft falls toward Earth at the same rate they do, so there's no normal force - hence zero apparent weight. True weightlessness only exists infinitely far from all mass.

Pounds (lb) actually refers to mass in everyday use, where 1 kg = 2.205 lb. Technically, the unit of weight is pounds-force (lbf). On Earth's surface, 1 kg of mass has a weight of 2.205 lbf. To convert: mass (kg) = mass (lb) ÷ 2.205, and weight (N) = weight (lbf) × 4.448.

G-force measures acceleration relative to Earth's gravity. 1g = 9.81 m/s² = normal Earth gravity. Fighter pilots experience up to 9g in tight turns (9× body weight). Astronauts experience about 3g during launch. At 2g, you weigh twice normal; at 0g (free fall), you're weightless. High g-forces can cause blackouts as blood flow is affected.