Enter your weight and see it converted across the solar system, using surface gravity figures from NASA’s planetary fact sheet.
The unit is just a label — the ratios are the same whichever you pick.
| Body | Surface gravity (m/s²) | Relative to Earth | You would weigh |
|---|
Surface gravity values from NASA’s NSSDCA Planetary Fact Sheet. For the gas giants, gravity is quoted at the 1 bar atmospheric level; all figures are equatorial and include the effect of rotation.
This is the distinction the whole page rests on. Mass is how much matter you are made of, and it does not change no matter where you go. Weight is the force gravity exerts on that mass, and it changes with wherever you happen to be standing.
Weight is W = m × g, where g is the local surface gravity. On Earth g is about 9.8 m/s². On the Moon it is 1.6, so the same body weighs roughly a sixth as much — but it still has exactly the same inertia. An astronaut can lift a heavy object easily on the Moon and will still be knocked flat if it swings into them, because resisting a sideways shove depends on mass, not weight.
Strictly, kilograms measure mass and newtons measure weight. Everyday usage conflates the two, and this calculator follows the everyday convention: it scales whatever number you enter by the gravity ratio, which is what people actually want to know.
Jupiter has 318 times Earth’s mass, so you might expect crushing gravity. It is only about 2.4 times Earth’s. The reason is distance: gravitational attraction falls off with the square of the distance from the centre, and Jupiter’s enormous radius puts its "surface" a very long way out. Mass pulls harder, radius pushes the surface further away, and the two effects largely cancel.
The same arithmetic explains why Saturn, despite being 95 times Earth’s mass, has surface gravity of about 9.0 m/s² — slightly less than Earth. Saturn is enormous but extraordinarily diffuse; its mean density is lower than water’s.
There is also the matter of "surface". The gas giants do not have one. The figures quoted are taken at the level where atmospheric pressure equals one bar, which is a convention, not a place you could stand.
Both come out at 3.7 m/s², which looks like an error and is not. Mars is much more massive than Mercury — about twice — but also considerably larger in radius. The mass-to-radius-squared ratio lands in almost the same place for both, so a visitor would feel about 38% of Earth weight on either.
Bone and muscle are maintained in response to load. Remove most of the load and the body sheds what it is not using: astronauts on long-duration missions lose bone mineral density at roughly 1 to 2% per month in the weight-bearing skeleton, despite exercise countermeasures, and muscle atrophy follows a similar path. Fluid redistributes upward, which affects vision through pressure on the optic nerve.
This is one of the more serious open problems for long-duration spaceflight, and it is why partial gravity on Mars — 38% rather than zero — is thought to be meaningfully better than the microgravity of orbit, though nobody has data on what years at 0.38 g actually do.
From Newton: g = GM / r², where G is the gravitational constant, M is the body’s mass and r its radius. Everything on this page follows from that one expression plus measured masses and radii. The published values also include a small correction for rotation, which slightly reduces effective gravity at the equator — noticeable on fast-rotating bodies like Saturn, negligible on the Moon.
Genuinely lighter, in the sense that matters: the force between you and the ground is about one sixth of what it is on Earth, so a bathroom scale would read one sixth. Your mass is unchanged, which is why you would still have full inertia — easy to lift, just as hard to stop once moving. The Apollo astronauts’ characteristic bounding gait comes from exactly this mismatch between low weight and unchanged inertia.
Because gravity falls off with the square of distance from the centre, and Jupiter’s radius is about 11 times Earth’s. Squaring that gives roughly 125, and 318 divided by 125 is about 2.5. The enormous mass pulls harder but the enormous size puts the surface much further from the centre, and the two effects nearly cancel. Saturn takes this further still — 95 Earth masses, but surface gravity slightly below Earth’s.
Coincidence, arising from the ratio of mass to radius squared landing in the same place. Mars is roughly twice Mercury’s mass but also substantially larger in radius, and the two differences cancel almost exactly. Both come out at about 3.7 m/s², or 38% of Earth. A visitor would not be able to tell them apart by weight alone.
It is a convention. For Jupiter, Saturn, Uranus and Neptune the value is quoted at the altitude where atmospheric pressure equals one bar — roughly Earth’s sea-level pressure. There is no solid ground there, only progressively denser gas, so the figure describes what a hypothetical platform at that level would experience rather than anywhere you could stand.
The Sun’s surface gravity is about 274 m/s², roughly 28 times Earth’s, so a 70 kg person would weigh the equivalent of about 1960 kg. It is left off the table because there is no surface in any meaningful sense — the photosphere is plasma at around 5500 °C — and because the answer is dominated by the fact that nothing could be there at all.
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