Weight is the gravitational force on an object, W = m·g, while mass is the fixed amount of matter in it. Drag the sliders below to set the mass and the gravity (or pick a world), and watch the weight change while the mass stays the same.
Load a single object onto the spring scale, then hop between destinations: a 1 kg mass reads 9.81 N on Earth, drops to about 1.62 N on the Moon, and climbs to nearly 25 N on Jupiter. Through all of it the Mass slider never moves on its own, because kilograms count the amount of stuff and that quantity travels unchanged from planet to planet. The Weight readout is doing something different: it reports a force in newtons, and force answers to gravity.
That split is the whole point of the panel. Set Mass in kilograms, then tap a world button — Moon (1.62), Mars (3.72), Earth (9.81), Jupiter (24.79) — or drag Custom gravity g to any value in between. The spring scale recomputes W = m·g instantly, so you can hold the mass fixed and let only g vary. Underneath, a second readout shows what an Earth kitchen scale would claim: it senses weight but prints kilograms assuming Earth's g, so off-world it misreads.
Push Custom gravity g toward zero — the deep-space case, far from any planet or star — and the weight collapses to nothing while the mass sits untouched. (Orbiting astronauts feel weightless for a different reason: they are in free fall, with gravity still strong around them.) To turn one of these weights into a lookup for real bodies, try the weight on other planets calculator, or carry the same object into another of our interactive physics labs.
Mass is the amount of matter in an object, measured in kilograms, and it is the same everywhere. Weight is the gravitational force on it, measured in newtons: W = m·g, so weight changes with gravity.
No. A 1 kg mass is 1 kg everywhere. Only the weight changes — on the Moon (g = 1.62) a 1 kg mass weighs about 1.62 N, roughly a sixth of its 9.81 N on Earth.
It senses your weight (a force), but is labelled in kilograms assuming Earth's gravity. Taken to the Moon or Jupiter the same scale would misread, because the same mass produces a different weight there.
Weightlessness is when the apparent weight is zero. Astronauts in orbit feel it because they are in continuous free fall, even though gravity is still strong around them — their mass is completely unchanged.