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Your Weight on Other Planets

See what a scale would read on 22 celestial bodies — planets, moons, dwarf planets and a neutron star — with NASA/JPL surface gravity and your unchanged mass shown alongside.

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lb

Unit

You would weigh

56.7 lb

on Mars — 62% lighter than on Earth

Your mass — the same everywhere

150 lb · 68.0 kg

Mass never changes with gravity. Only the force does.

Your weight as a force

252 N

667 N on Earth

Surface gravity there

3.71 m/s²

Mars — 0.378 times Earth's gravity

Surface gravity from NASA/JPL Solar System Dynamics. Jupiter, Saturn, Uranus and Neptune have no solid surface, so the figure is the one at the 1-bar pressure level. Earth's reference is standard gravity, 9.80665 m/s².

Your weight on 22 celestial bodies

Celestial body Surface gravity vs Earth You would weigh As a force
Planets
Mercury 3.70 m/s² 0.377 56.6 lb 252 N
Venus 8.87 m/s² 0.904 136 lb 604 N
Earth 9.80665 m/s² 1.00 150 lb 667 N
Mars 3.71 m/s² 0.378 56.7 lb 252 N
Jupiter (1 bar) 24.79 m/s² 2.53 379 lb 1,687 N
Saturn (1 bar) 10.44 m/s² 1.06 160 lb 710 N
Uranus (1 bar) 8.87 m/s² 0.904 136 lb 604 N
Neptune (1 bar) 11.15 m/s² 1.14 171 lb 759 N
Dwarf planets
Ceres 0.284 m/s² 0.0289 4.34 lb 19.3 N
Pluto 0.62 m/s² 0.0632 9.48 lb 42.2 N
Eris 0.81 m/s² 0.0824 12.4 lb 55.0 N
Moons
The Moon 1.624 m/s² 0.166 24.8 lb 111 N
Io 1.796 m/s² 0.183 27.5 lb 122 N
Europa 1.315 m/s² 0.134 20.1 lb 89.5 N
Ganymede 1.428 m/s² 0.146 21.8 lb 97.2 N
Callisto 1.236 m/s² 0.126 18.9 lb 84.1 N
Titan 1.354 m/s² 0.138 20.7 lb 92.1 N
Enceladus 0.1135 m/s² 0.0116 1.74 lb 7.72 N
Triton 0.7808 m/s² 0.0796 11.9 lb 53.1 N
Stars and extreme gravity
The Sun 274.2 m/s² 28.0 4,194 lb 18,656 N
White dwarf (Sirius B) 3.90 × 10⁶ m/s² 3.98 × 10⁵ 5.96 × 10⁷ lb 2.65 × 10⁸ N
Neutron star (model: 1.4 solar masses, 10 km) 1.86 × 10¹² m/s² 1.89 × 10¹¹ 2.84 × 10¹³ lb 1.26 × 10¹⁴ N

How this is calculated

Your mass: 150 lb × 0.45359237 = 68.0 kg

Surface gravity on Mars: g = 3.71 m/s²

Compared with Earth: 3.71 ÷ 9.80665 = 0.378

Scale reading on Mars: 150 lb × 0.378 = 56.7 lb

Actual weight there: 68.0 kg × 3.71 m/s² = 252 N

Where the number comes from: g = GM ÷ r², from a published mass and radius measured by spacecraft or telescope.

Weight on other planets calculator. What a scale would read on 22 celestial bodies.

Your mass never changes from one body to the next; only the force does, so this calculator turns your Earth weight into what a scale would read elsewhere. Enter a weight in pounds, kilograms or stones, pick one of 22 celestial bodies, and it reports the scale reading, your mass, the gravitational force and the local surface gravity.

Mass, Weight, and What a Scale Would Really Read

Your weight on another body is the force its gravity exerts on you — your mass multiplied by the local surface gravity. Mass is the quantity of matter you are made of, and it reads the same on Earth, on Mars and halfway between them. Gravity is the only term that changes from one body to the next, which is why a 150 lb person reads 56.7 lb on Mars, 24.8 lb on the Moon and 379 lb at Jupiter's 1-bar level while their mass sits at 68.0 kg throughout.
The confusion is baked into the units themselves. The pound and the kilogram measure mass — the international avoirdupois pound has been exactly 0.45359237 kilograms since the 1959 International Yard and Pound Agreement, and the SI unit of force is the newton. Everyday English uses both for weight anyway, and Wikipedia's article on mass versus weight points out that the "net weight" printed on a retail package is a mass. So "you would weigh 57 lb on Mars" is shorthand for something more careful: a spring scale calibrated on Earth, carried to Mars, would come to rest at the 57 lb mark. Your mass is still 68.0 kg, and the force Mars exerts on you is 252 newtons against the 667 newtons you feel here.
Four of the bodies in the list have no surface to stand on. Jupiter, Saturn, Uranus and Neptune thicken from gas to liquid with depth, so surface gravity has to be quoted at a chosen level, and the convention astronomers settled on is the altitude where atmospheric pressure reaches 1 bar — Earth's sea-level pressure. Wikipedia's Surface gravity article states it directly: "For gas giant planets such as Jupiter, Saturn, Uranus, and Neptune, surface gravity is given at the 1-bar pressure level in the atmosphere." Every giant-planet figure here carries that label inside its own name, because a value quoted at the cloud tops instead comes out several percent lower and nothing distinguishes the two once the label is dropped.
Size is a poor guide to gravity, and the table of 22 bodies makes that checkable in three places. Venus and Uranus land on the same 8.87 m/s² to three significant figures, even though JPL's table gives Uranus 86.8 × 10²⁴ kg against Venus's 4.87 × 10²⁴ — almost eighteen times the mass — because Uranus's bulk density is 1.270 g/cm³ against Venus's 5.243, and its 1-bar level sits far further from the center. Ganymede is the largest moon in the solar system and wider than Mercury, yet a 150 lb visitor reads 21.8 lb there against 56.6 lb on Mercury. And Io, whose radius is only about 69% of Ganymede's, still pulls harder — 1.796 m/s² against 1.428 — because Io is the denser body: Wikipedia's infoboxes give it 3.528 g/cm³ where Ganymede's says 1.936. Wikipedia gives the broad version of this a name: "for giant planets with masses up to 100 times that of Earth, surface gravity is nevertheless very similar and close to 1 g, a region known as the gravity plateau."
Every constant here has one source and one stated convention. The eight planets and Pluto take the Equatorial Gravity column of NASA/JPL Solar System Dynamics, which is the gravitational attraction with nothing subtracted for the planet's spin. The eight moons plus Ceres are worked out as GM divided by mean radius squared, from the GM and radius JPL publishes for each, because JPL prints no gravity column for satellites. Eris is assembled from two papers, and the Sun from the International Astronomical Union's nominal constants. Earth's own reference is standard gravity, 9.80665 m/s², defined exactly by the third General Conference on Weights and Measures in 1901 — a number chosen, never measured, which is what makes every ratio on this page reproducible with a pocket calculator. Real Earth gravity does wander: Wikipedia's Gravity of Earth puts it at 9.7639 m/s² on Nevado Huascarán in Peru and 9.8337 m/s² at the surface of the Arctic Ocean, a 0.7% spread that moves a 150 lb reading by about one pound depending on where you put the scale down.

Surface Gravity and Scale Readings for the Celestial Bodies Most People Ask About

Celestial bodySurface gravityvs Earth150 lb reads68 kg reads
The Moon1.624 m/s²0.16624.8 lb11.3 kg
Mars3.71 m/s²0.37856.7 lb25.7 kg
Mercury3.70 m/s²0.37756.6 lb25.7 kg
Venus8.87 m/s²0.904136 lb61.5 kg
Earth9.80665 m/s²1.00150 lb68.0 kg
Jupiter (1 bar)24.79 m/s²2.53379 lb172 kg
Saturn (1 bar)10.44 m/s²1.06160 lb72.4 kg
Uranus (1 bar)8.87 m/s²0.904136 lb61.5 kg
Neptune (1 bar)11.15 m/s²1.14171 lb77.3 kg
Pluto0.62 m/s²0.06329.48 lb4.30 kg
Titan1.354 m/s²0.13820.7 lb9.39 kg
Enceladus0.1135 m/s²0.01161.74 lb0.787 kg
The Sun274.2 m/s²28.04,194 lb1,901 kg

The Formula Behind Every Row

W=m⋅gg=GMr2W = m \cdot g \qquad g = \dfrac{GM}{r^{2}}
  • WW = Weight — the gravitational force acting on you there, in newtons
  • mm = Your mass in kilograms. Identical on every body in the list.
  • gg = The local surface gravity in meters per second squared — 3.71 on Mars, 1.624 on the Moon, 24.79 at Jupiter's 1-bar level
  • g0g_{0} = Standard gravity, exactly 9.80665 m/s². The Earth reference every ratio on the page divides by.
  • GG = The gravitational constant, 6.674 × 10⁻¹¹ m³ kg⁻¹ s⁻²
  • MM = The mass of the celestial body you are standing on
  • rr = Its radius, from the center out to the surface — or to the 1-bar level, for a planet that has no surface
Three equations do all the work here, and none of them hides a term.
The first turns a mass into a force. Multiply your mass in kilograms by the local surface gravity in meters per second squared and the answer is a weight in newtons. A 68.0 kg person on Mars: 68.0 × 3.71 = 252 N, against 68.0 × 9.80665 = 667 N at home. That newton figure is the physically honest answer to "what do you weigh there", and it is the one the calculator prints on the third card.
The second is what the scale shows. A bathroom scale is a spring calibrated against Earth's gravity, so the pounds or kilograms it prints scale by the gravity ratio and nothing else:
scale reading=wEarth×gg0\text{scale reading} = w_{\text{Earth}} \times \frac{g}{g_{0}}
Mars works out to 3.71 ÷ 9.80665 = 0.378, so 150 × 0.378 = 56.7 lb. The same 0.378 applies to any input in any unit, which is why the ratio column is the one worth memorizing.
The third equation is where the constants themselves come from. Surface gravity falls out of a body's mass and its radius:
g=GMr2g = \frac{GM}{r^{2}}
Enceladus is the cleanest demonstration. JPL publishes GM = 7.21037 km³/s² and a mean radius of 252.10 km for it; convert both to SI units and 7.21037 × 10⁹ ÷ (2.5210 × 10⁵)² = 0.1135 m/s². Wikipedia's Enceladus infobox prints 0.113 m/s² and 0.0116 g — the same arithmetic carried to one digit fewer.
The r² in the denominator is why size misleads. Doubling a body's mass doubles its surface gravity, while doubling its radius quarters it. A large, low-density planet can therefore pull no harder than a small dense one, which is how Uranus lands on the same 8.87 m/s² as Venus while carrying almost eighteen times the mass.

Worked Examples Across the Solar System

150 lb on Mars — all four numbers at once

This is the calculator's opening state, and it shows why one number was never enough. The scale reads 56.7 lb, which the card describes as 62% lighter than on Earth. Your mass is unchanged at 150 lb, or 68.0 kg. Your actual weight — the force Mars pulls on you with — is 252 N, against 667 N on Earth. And Mars's surface gravity is 3.71 m/s², which is 0.378 times Earth's.
The arithmetic runs 150 × (3.71 ÷ 9.80665) = 56.7 for the scale, and 68.0 × 3.71 = 252 for the force. Nothing in either line touches your mass, and that is the whole lesson: a Mars colonist would need the same food, take the same dose of medicine and hit a wall with the same momentum as they do here.

70 kg on Mars and the Moon — the metric version

Switch the unit toggle to kilograms and type 70. On Mars the scale reads 26.5 kg while your mass stays 70.0 kg, and the force is 260 N against 686 N on Earth. On the Moon the same person reads 11.6 kg, with the force at 114 N.
The toggle rescales whatever is already in the field, so a 150 in pounds becomes 68 in kilograms and 10.7 in stones — the same person each time, described three ways. If you only wanted the pound-to-kilogram step and none of the astronomy, the mass converter does it directly.

The Apollo suit problem: 380 lb becomes 62.9 lb

An Apollo lunar suit with its life-support backpack weighed nearly as much as the astronaut inside it. Take a 195 lb astronaut in a 185 lb suit: 380 lb on Earth, and 380 × 0.1656 = 62.9 lb on the Moon. The mass card still reads 172 kg, and the force drops from 1,690 N to 280 N.
That gap explains two things at once. Training in the same rig on Earth was punishing, because the full 1,690 N had to be carried on a set of knees. And walking on the Moon looked easy while remaining hard to control, because the 172 kg of mass — which sets how much shove it takes to start moving and how much to stop — never went anywhere.

The eight moons, ranked by what a 150 lb visitor reads

Size predicts the order badly. Rank these eight by radius and Ganymede leads with Titan behind it; rank them by what a scale reads and the winner is fourth on that list, with Earth's Moon fifth:
  • Io — 1.796 m/s², 0.183×, 27.5 lb. The strongest of the eight, and stronger than Earth's own Moon, at a mean density of 3.528 g/cm³.
  • The Moon — 1.624 m/s², 0.166×, 24.8 lb. The familiar "one sixth" rounds this 0.1656 up, so the folk figure sits a shade heavy.
  • Ganymede — 1.428 m/s², 0.146×, 21.8 lb. The largest and most massive moon in the solar system, and wider than Mercury, but only 45% of Mercury's mass.
  • Titan — 1.354 m/s², 0.138×, 20.7 lb. The only moon with an atmosphere denser than Earth's — 1.45 atm at the surface.
  • Europa — 1.315 m/s², 0.134×, 20.1 lb. The smallest of Jupiter's four Galilean moons.
  • Callisto — 1.236 m/s², 0.126×, 18.9 lb. Second largest of the Galileans and the weakest of them.
  • Triton — 0.7808 m/s², 0.0796×, 11.9 lb. Neptune's largest moon.
  • Enceladus — 0.1135 m/s², 0.0116×, 1.74 lb. The weakest pull of any solar-system body on the list.
Ganymede against Io is the pairing worth keeping. Ganymede's radius is about 45% larger, and it still comes second, because Io is nearly twice as dense — Wikipedia's infoboxes put Io at 3.528 g/cm³ and Ganymede at 1.936. Gravity follows mass over radius squared, and diameter enters that expression only through the denominator.

Venus and Uranus: 8.87 m/s² each, and the one table where they split

Two planets with almost nothing in common produce the same reading. Venus is a rocky planet at 5.243 g/cm³; Uranus is an ice giant at 1.270 g/cm³ with nearly eighteen times the mass. Both land on 8.87 m/s², both come out at 0.904 times Earth, and both put a 150 lb person at 136 lb.
The coincidence survives only in the gravitational column. Wikipedia's surface-gravity table splits them — Venus 0.905 g, Uranus 0.886 g — because Uranus's row is quoted at the equator, where its spin takes a bite out of the number, while Venus's row is a midlatitude figure with nothing taken out of it at all. JPL's rotation periods explain why that matters for one planet and not the other: Uranus turns once in 0.71833 days, about 17 hours, and Venus takes 243.018 days. Same gravity, different spin, two published answers.

Saturn: three published answers, and they disagree about the direction

Ask whether you would weigh more or less on Saturn and the honest reply is that it depends on which quantity the source picked. Three are published:
  • JPL's equatorial gravity, 10.44 m/s², is what this calculator uses. Divided by 9.80665 it gives 1.06, so 150 lb reads 160 lb — about 6% heavier.
  • NASA's planetary fact sheet publishes a mean gravity of 11.19 m/s², which is 1.141 times Earth's and would put the same person near 171 lb — about 14% heavier.
  • The same fact sheet publishes an equatorial acceleration of 8.96 m/s², which subtracts the centrifugal effect of Saturn's ten-and-a-half-hour day. That is 0.914 times Earth's, or roughly 137 lb — about 9% lighter.
NASA's StarChild pages for students print 0.93 for Saturn, landing close to the third answer. Every one of those figures came off a published table. Saturn is the planet where the choice of quantity flips the sign of the answer, which is why the choice is named on screen here.

Enceladus: 1.74 lb, and one pound reads as a fifth of an ounce

Saturn's small icy moon has the weakest pull in the solar-system half of the list. A 150 lb person reads 1.74 lb there — 0.787 kg in metric — with a force of 7.72 N. Drop the input to 1 lb and the scale reads 0.0116 lb, roughly a fifth of an ounce.
Enceladus's escape velocity is 0.239 km/s, and its south polar vents throw about 200 kilograms of water-rich material per second into space, where it feeds Saturn's E ring instead of falling back. Gravity this weak barely holds a moon's own plumes down.

The extreme group: the Sun, a white dwarf and a neutron star

The last three options run the same multiplication at gravities the solar system cannot supply.
The Sun comes to 274.2 m/s², or 28.0 times Earth. A 150 lb person reads 4,194 lb — a little over two tons — with a force of 18,656 N.
Sirius B, the white dwarf companion of the brightest star in the night sky, has a measured surface gravity of 3.90 × 10⁶ m/s², which is 3.98 × 10⁵ times Earth. The reading becomes 5.96 × 10⁷ lb, close to 30,000 tons.
The neutron-star option carries its parameters in the picker's own label: 1.4 solar masses inside a 10 km radius, which is the scale NASA describes for a typical neutron star. Newtonian gravity there is 1.86 × 10¹² m/s², so the scale reads 2.84 × 10¹³ lb — around fourteen billion tons. General relativity raises that by roughly a third again for those parameters. NASA's own comparison for the same material is that a single sugar cube of it would weigh about a billion tons on Earth.

Earth's own gravity is not a single number either

The reference this page divides by, 9.80665 m/s², was settled by international agreement in 1901, and the real planet varies around it. Wikipedia's Gravity of Earth gives 9.7639 m/s² on Nevado Huascarán in Peru as the low and 9.8337 m/s² at the surface of the Arctic Ocean as the high, with sea-level values running from about 9.780 at the equator to 9.832 at the poles.
For a 150 lb person that whole range is worth about one pound: the same body, the same scale, a different spot on the planet. Earth's rotation accounts for a chunk of it, removing up to 0.3% of apparent weight at the equator. That entire 0.7% spread is still smaller than the gap between the three published Saturn figures above.

How to Use the Weight on Other Planets Calculator

Three controls run the whole page:
1. Type your weight on Earth into the first field. Anything from 0 to 2000 is accepted, and a decimal point or comma both work.
2. Pick your unit — pounds, kilograms or stones. Switching rescales the number already in the field, so 150 lb becomes 68.0 kg and then 10.7 st, describing the same person each time.
3. Choose a celestial body from the picker. The 22 options are filed under four headings — planets, dwarf planets, moons, and stars and extreme gravity — so Titan and Enceladus sit together under Moons.
Four cards answer at once, laid out two by two. The first is the scale reading in your own unit, with the change against Earth spelled out underneath. Beside it sits your mass, shown in both your unit and kilograms, because it is the number that does not move. Below those are your weight as a force in newtons, with the Earth value alongside for contrast, and the local surface gravity with its ratio to Earth. A copy icon sits next to the scale reading; press it to put the number on your clipboard.
Under the cards, a table lists all 22 celestial bodies at your weight simultaneously, with the row for your selection highlighted. Scanning it is faster than changing the picker 22 times, and it is where the counterintuitive pairs stand out — Venus level with Uranus, Ganymede below Io, Mercury a hair under Mars.
The address bar tracks all three controls, so a link carries the full state: ?weight=70&unit=kg&body=moon opens on the Moon with 70 kg already in the field. Send a bare ?body=moon and the recipient still lands on the Moon, at the default 150 lb, which is often what a class handout wants anyway.
One collapsed panel, "How this is calculated", shows the substitution line by line with your own numbers: your mass in kilograms, the local gravity, the ratio against 9.80665, the scale reading, the force in newtons, and a line naming where that gravity figure comes from. Open it when you have to show your working.
The number to write down depends on what was asked. For a physics assignment, the newtons figure is the weight and your mass in kilograms is the invariant that has to be quoted alongside it. In conversation, the scale reading in pounds or kilograms is what people mean. If you need those newtons converted into pounds-force, kilogram-force or dynes, the force converter handles them directly.

Mistakes That Show Up in Almost Every Answer

  • Saying your mass changes on the Moon. It does not. A 150 lb person is 68.0 kg on Earth, on the Moon and in the space between them. What drops is the force: 111 N on the Moon against 667 N here, which a scale reports as 24.8 lb. That is why the mass gets a card of its own on this page, the same size as the result beside it.
  • Treating the kilogram as a unit of weight. The kilogram measures mass and the newton measures force, and the BIPM's SI brochure keeps them in separate categories. The habit of reading a bathroom scale in kilograms works on Earth only because the scale was calibrated against Earth's gravity before it left the factory. Carry it to Mars without recalibrating and it will report 25.7 kg for the same unchanged 68.0 kg body.
  • Assuming a gas giant has a surface. Jupiter, Saturn, Uranus and Neptune do not, so a "surface gravity" for them is a figure quoted at a chosen pressure level — 1 bar, by convention. Some sources quote the cloud tops instead, which sits at a different altitude and gives a lower number. Two calculators that made different choices will disagree by several percent, and both will be reporting exactly the quantity they picked.
  • Trusting the ratio without asking which quantity produced it. At least five Jupiter multipliers are in print. Omnicalculator and CalcTool publish 2.34, Caltech's Cool Cosmos rounds to 2.4, NASA's StarChild pages give 2.54, this calculator and Wikipedia's Jupiter infobox both work from 2.528 — which the table here prints as 2.53 at three significant figures — and NASA's fact-sheet mean-gravity row works out near 2.64. Those five figures measure five different things, and the word "gravity" covers all of them.
  • Reading Pluto's 9.48 lb as a planet's figure. Pluto has been a dwarf planet since the International Astronomical Union's 2006 definition, which is why the picker files it with Ceres and Eris. This page flags that precision separately: Pluto and Ceres are known to three figures or fewer, and Eris has to be assembled from two separate papers — a moon's orbit for the mass, a stellar occultation for the radius. The seven planets other than Earth are pinned by spacecraft that reached them, orbiting in most cases and on a single Voyager 2 flyby at Uranus and Neptune, and Earth's own figure is fixed by convention.
  • Thinking astronauts float because gravity stopped. NASA puts it plainly for the space station's altitude: "Earth's gravity is about 90 percent of what it is on the planet's surface", and "if a person who weighed 100 pounds on Earth's surface could climb a ladder all the way to the space station, that person would weigh 90 pounds at the top of the ladder." They float because the station and everything in it are falling together at the same rate.
  • Expecting a jump height or a running speed out of these numbers. Lower gravity changes what a scale reads, and it changes how high a jump carries. It leaves your mass alone, so the effort of accelerating yourself sideways, or of stopping once moving, is the same everywhere. That is a different calculation with different inputs, and this page deliberately does not guess at it.

The Vocabulary of Mass, Weight and Gravity

Mass

The quantity of matter in a body, measured in kilograms. It does not move with location: 68.0 kg on Earth is 68.0 kg on Enceladus and 68.0 kg in orbit. The same number is the inertia term in Newton's second law, F = ma, so mass governs acceleration as well as weight.

Weight

The gravitational force acting on a mass, equal to mass times the local surface gravity and measured in newtons. It moves with location: the same 68.0 kg body weighs 667 N on Earth, 252 N on Mars and 111 N on the Moon. Everyday English borrows the word for mass as well, which is where most of the confusion around this topic begins.

Newton (N)

The SI unit of force, 1 N = 1 kg·m/s² — the force that accelerates one kilogram at one meter per second squared. It is the unit a physics answer wants for a weight, and it is what the third card on this page prints.

Surface gravity

The acceleration a body's gravity produces at its surface, in meters per second squared, worked out as GM divided by the radius squared. A body with no solid ground needs a chosen reference level for it, and a fast-spinning irregular body has a different value depending on where you stand, which is why Haumea is absent from the picker.

Standard gravity (g₀)

The conventional value 9.80665 m/s², settled by the third General Conference on Weights and Measures in 1901 and exact by definition. Real Earth gravity sits anywhere between about 9.7639 and 9.8337 m/s² depending where the scale is put down, so the standard works as an agreed anchor for the whole table. Every ratio here divides by it, which keeps the arithmetic identical for anyone who checks the digits.

The 1-bar level

The altitude in a giant planet's atmosphere where the pressure matches Earth's at sea level. Jupiter, Saturn, Uranus and Neptune have no ground to stand on, so their surface gravity is published at that level by convention, and the picker prints "(1 bar)" after each of the four names.

Dwarf planet

The category the International Astronomical Union created in 2006 for a body that orbits the Sun, is round under its own gravity, has not cleared its orbital neighborhood of debris, and is not a satellite. That fourth condition is what keeps Ganymede and Titan out of the group, since both are wider than Pluto and both orbit a planet. Ceres, Pluto and Eris are the three that appear here, and they form their own group in the picker.

Spring scale

Any instrument that measures force from how far a spring stretches or how much a strain gauge deforms under load, then converts that force to a mass reading before displaying it. Bathroom scales, luggage scales and hanging produce scales all belong to this family; the beam balance belongs to the other one, which weighs by comparison.

Free fall

Motion under gravity alone, with no surface pushing back. The space station and everyone inside it fall around Earth together, which is why astronauts float even though NASA puts the gravity at that altitude around 90 percent of the surface value. What weightlessness registers is the missing push from a floor; the pull of the planet is still there.

Weight on Other Planets — Frequently Asked Questions

How much would I weigh on Mars?
Multiply your Earth weight by 0.378. A 150 lb person reads 56.7 lb on Mars, and a 70 kg person reads 26.5 kg. Mars's surface gravity is 3.71 m/s² against Earth's 9.80665, so the force on a 68.0 kg body drops from 667 N to 252 N while the mass stays at 68.0 kg.

Does your mass change on the Moon?
No. Mass is the amount of matter in you, and it is the same everywhere. Only your weight changes: on the Moon a 150 lb person's scale reads 24.8 lb, while their mass stays 68.0 kg and the force drops from 667 N to 111 N.

What is the difference between mass and weight?
Mass is how much matter you are made of, measured in kilograms; weight is the gravitational force pulling on that matter, measured in newtons. Mass is identical on all 22 celestial bodies listed here. The same 68.0 kg body weighs 667 N on Earth and 252 N on Mars.

Does a bathroom scale measure mass or weight?
A bathroom scale measures force and prints mass units. The spring or strain gauge inside responds to how hard you press on it, and the display divides that force by the gravity value the scale was calibrated against at the factory. Wikipedia's Weighing scale article gives the size of that dependence without leaving the planet: a spring scale's reading "varies with the strength of the local gravitational force (by as much as 0.5% at different locations on Earth)", and a scale used in trade "must be calibrated where it is used". A beam balance is the exception, because it compares your body with reference masses on the opposite arm and gravity acts on both sides equally. Carried to Mars, a balance would still report 68.0 kg; a bathroom scale reads 56.7 lb, or 25.7 kg, for the same unchanged body.

Why do gas giants have no surface gravity?
Jupiter, Saturn, Uranus and Neptune have no solid ground; they thicken from gas to liquid with depth. Wikipedia's Surface gravity article records the convention: quote the figure at the 1-bar pressure level, where the atmosphere reaches Earth's sea-level pressure. That is what this calculator uses for all four.

How much would I weigh on the Moon?
About a sixth of your Earth weight. The exact ratio is 0.166, so 150 lb reads 24.8 lb and 70 kg reads 11.6 kg. The Moon's surface gravity is 1.624 m/s², derived from the GM of 4,902.800 km³/s² and the 1,737.4 km mean radius that JPL publishes for it. The popular "one sixth" rounds that 0.1656 up to 0.1667, so it runs about six tenths of a percent heavy: a sixth of 150 lb is 25.0 lb where the table says 24.8.

Would I weigh less on Mercury or on Mars?
On Mercury, by a hair. Mercury's surface gravity is 3.70 m/s² against Mars's 3.71, so the ratios land on 0.377 and 0.378 and a 150 lb person reads 56.6 lb on Mercury against 56.7 lb on Mars. As a force the gap disappears: both print 252 N at three significant figures. Most tables round the pair to 0.38 and lose the distinction, and CalcTool's planet list gives Mercury 0.38 g and Mars 0.38 g on the same page. Density is what keeps the two level. Mercury's mean radius is 2,439.7 km, well under Mars's, and it holds the tie at 5.427 g/cm³ as the densest planet after Earth, with an iron-rich core filling roughly 57% of its volume against Earth's 17%.

Why do different calculators give different gravity numbers for Jupiter?
Because three separate quantities circulate under the single word "gravity". JPL's Equatorial Gravity column, which this page uses, gives 24.79 m/s², a ratio of 2.528 that the table prints as 2.53 at three significant figures. NASA's planetary fact sheet publishes a mean gravity of 25.92 m/s², computed against a smaller radius, and an equatorial acceleration of 23.12 m/s² that subtracts Jupiter's ten-hour spin. Omnicalculator quotes 22.96 m/s² at the cloud tops, and Caltech's Cool Cosmos rounds to 2.4. All five are published, and each answers a question a different source chose to ask.

Would I weigh more or less on Saturn than on Earth?
Both answers are in print, which makes Saturn the most interesting planet on this list. Using JPL's equatorial gravity of 10.44 m/s², you weigh about 6% more — 150 lb reads 160 lb, and that is what this calculator shows. Using NASA's equatorial acceleration of 8.96 m/s², which subtracts the centrifugal effect of Saturn's ten-and-a-half-hour day, you weigh about 9% less, near 137 lb. NASA's own StarChild pages print 0.93 for Saturn and land on the lighter side too. What the sources disagree about is which quantity gets to be called "gravity".

How much would I weigh on Jupiter?
About two and a half times your Earth weight. A 150 lb person reads 379 lb and a 68 kg person reads 172 kg, using Jupiter's 1-bar gravity of 24.79 m/s², which is 2.53 times Earth's. There is no surface to stand on, so the figure describes the level where the atmospheric pressure matches Earth's at sea level.

How much would I weigh on the Sun?
About twenty-eight times what you weigh here. The Sun's surface gravity is 274.2 m/s², which is 28.0 times Earth's at the three figures this page prints, so 150 lb reads 4,194 lb — a little over two tons — and 70 kg reads 1,957 kg, with the force at 19,194 N. The Sun has no more of a solid surface than Jupiter does. NASA's own fact page states that "The Sun doesn't have a solid surface like Earth and the other rocky planets and moons", and the layer people mean by its surface is the photosphere. The radius behind that 274.2 is the IAU's nominal solar radius of 6.957 × 10⁸ m, fixed by resolution in 2015, which is why the "How this is calculated" panel files the Sun's gravity under values defined by convention.

How much would I weigh on Pluto?
Roughly a sixteenth of your Earth weight. Pluto's surface gravity is 0.62 m/s², a ratio of 0.0632, so a 150 lb person reads 9.48 lb and a 70 kg person reads 4.43 kg, with the force down from 686 N to 43.4 N. Pluto is also the coarsest constant on the page: JPL publishes it to two figures, so 0.62 is all the precision there is and the calculator prints no more than that. Published figures disagree by more than a quarter. NASA's Pluto fact page calls its gravity "about 6% of Earth's", which matches the 6.32% here, while Caltech's Cool Cosmos rounds to a twelfth and puts a 100 lb person at 8 lb against this page's 6.32 lb. Pluto sits in the dwarf-planet group of the picker alongside Ceres and Eris because the International Astronomical Union's 2006 definition moved it there.

Is a pound a unit of mass or of weight?
Of mass. The international avoirdupois pound is exactly 0.45359237 kilograms, fixed by the 1959 International Yard and Pound Agreement. Its matching unit of force is the pound-force, which NIST lists as 4.448222 newtons. Everyday English uses "pound" for both, which works on Earth because the local gravity is near enough constant, and stops working the moment you leave Earth.

What do I write for weight in a physics assignment — kilograms or newtons?
Newtons. Weight is a force and the SI unit of force is the newton, so the line that gets graded for a 150 lb person on Mars is 252 N, against 667 N on Earth. Put the mass beside it in kilograms — 68.0 kg — because it is the quantity that does not move, and a mass-versus-weight question is usually asking for both. DocBrown's GCSE physics notes state the relationship as W (N) = m (kg) × g (N/kg) and warn in capitals that "Mass is NOT the same as weight", while OpenStax's University Physics makes the same point about everyday habit: "our medical records often show our weight in kilograms but never in the correct units of newtons". Keep the scale reading of 56.7 lb for explaining the idea to someone. Open the "How this is calculated" panel to copy the substitution line by line with your own numbers, and expect a small mismatch if your course rounds Earth's gravity to 9.8 or 10 N/kg, because this page uses the defined 9.80665 m/s².

How much would I weigh on a neutron star?
For the model in the picker — 1.4 solar masses packed into a 10 km radius — a 150 lb person's scale would read 2.84 × 10¹³ lb, about fourteen billion tons. That is the Newtonian number; general relativity adds roughly another third for those parameters. NASA's own comparison for neutron-star material is that one sugar cube of it would weigh about a billion tons on Earth. The picker labels the option a model and prints its mass and radius, because no observed neutron star has been pinned to exactly those two figures.

Which moon would I weigh the most on?
Io. A 150 lb person reads 27.5 lb there, ahead of Earth's Moon at 24.8 lb and Ganymede at 21.8 lb. Io wins on density: Wikipedia's infoboxes give it 3.528 g/cm³ against Ganymede's 1.936, even though Ganymede is the largest moon in the solar system and its radius is about 45% greater. Enceladus sits at the other end at 1.74 lb.

How much would I weigh on Titan?
A 150 lb person reads 20.7 lb on Titan and a 70 kg person reads 9.67 kg. Saturn's largest moon has a surface gravity of 1.354 m/s², which is 0.138 times Earth's, and the force on a 68.0 kg body there is 92.1 N. That reading is lighter than on our own Moon, which puts the same person at 24.8 lb, even though Titan is the bigger body by a wide margin: Wikipedia's Titan article has it 48.16% larger in diameter than the Moon and 80% more massive. Mass over radius squared is why the larger body loses. The cold is what makes Titan hostile: the Planetary Society puts the surface at about minus 179 °C. Pressure is the easy part, at about 1.45 atm, so a visitor would need heat and oxygen but could skip the pressure shell. That combination of thick air and weak gravity is generous enough that, in the same article's words, "it could even be possible for a human to strap wings onto their spacesuit, flap those wings, get a running start, and take off".

Why do you weigh less on Ganymede than on the Moon if Ganymede is bigger?
Because gravity divides by the radius squared, and Ganymede is the wider body. It is the largest moon in the solar system — NASA gives its diameter as 5,260 km against Mercury's 4,880 km — and Wikipedia puts its mass at more than twice the Moon's. Its radius is also about half again the Moon's, and squaring that denominator more than cancels the extra mass: 1.428 m/s² against the Moon's 1.624, so a 150 lb person reads 21.8 lb on Ganymede and 24.8 lb on the Moon. Composition is what sits underneath the arithmetic. Ganymede's mean density is 1.936 g/cm³ against the Moon's 3.344, because NASA describes Ganymede as an iron core under a rock mantle under a thick shell of ice, while Wikipedia ranks the Moon the second-densest satellite in the solar system behind Io. The same trade leaves Ganymede at only 45% of Mercury's mass while being the larger of the two.

Why are astronauts weightless in orbit if gravity is still there?
They are in free fall. NASA states that at the space station's altitude "Earth's gravity is about 90 percent of what it is on the planet's surface", and that someone who weighed 100 pounds on the ground would weigh 90 pounds at the top of a ladder that tall. The station and everyone inside it fall around Earth together, so nothing pushes up on anyone — and the absence of that push is what weightlessness feels like.

Why isn't Haumea in the list?
Because Haumea's surface gravity is a range. Its 3.9-hour spin has stretched the dwarf planet into an elongated ellipsoid, and a 2023 study of its crater shapes puts the effective figure at 0.0126 m/s² on the tip of the equatorial long axis and 1.076 m/s² at the poles, almost two orders of magnitude apart. A single number would be wrong nearly everywhere on the body. Makemake is missing for a second reason: its mass is loosely enough constrained that any gravity published for it would be a density assumption dressed up as a measurement.

Can you calculate weight on a black hole or on an exoplanet?
No, and both omissions are deliberate. A black hole has no surface, so surface gravity is undefined for one — Wikipedia's Surface gravity article says so directly, and the renormalized value physicists compute at the event horizon is a different quantity that Newtonian arithmetic cannot reach. Exoplanet figures are model-dependent and get revised as new measurements arrive, so any number here would silently go stale. Every constant on this page is either defined by convention or a published measurement stable to the digits shown.

Why does this page show 0.81 m/s² for Eris when most sources say 0.82?
Because 0.82 rests on a mass that has since been superseded. Eris is weighed by watching its moon Dysnomia, and that method returns the mass of the whole system: Brown & Schaller put the system at (1.67 ± 0.02) × 10²² kg in 2007, and over Eris's 1,163 km occultation radius that gives 0.82 m/s². Holler and colleagues refitted Dysnomia's orbit from seven Hubble orbits in 2021 and landed on 1.6466 × 10²², and that revision alone moves the answer to 0.81. This page then subtracts Dysnomia itself, about 8.2 × 10¹⁹ kg from Brown & Butler's 2023 ALMA limit, because a scale standing on Eris feels Eris and not its moon. That subtraction is smaller than its own error bar — Eris alone is 1.638 ± 0.014 × 10²² kg — so it moves nothing at two digits; the page does it so a system mass never gets printed as a body mass. The result is 0.81 m/s², or 12.4 lb for a 150 lb visitor.

How accurate are these numbers?
The arithmetic adds no error of its own: every result is one multiplication against a published constant, and Earth's reference of 9.80665 m/s² is exact by definition. The uncertainty lives in the constants. Planetary and lunar figures come from JPL's spacecraft-derived solutions and are stable well beyond the three significant figures shown. The neutron-star row is a stated model, with its mass and radius printed in its own label. And "gravity" itself is ambiguous by a few percent for the giant planets, depending on whether rotation and oblateness are folded in — which is why the convention appears on screen in the line under the cards.

Is this calculator free, and can I use it in class?
Yes to both. It runs in your browser with no account, accepts pounds, kilograms or stones, and shows all 22 celestial bodies at once so a whole class can read their own row off a projected table. Every gravity figure traces back to NASA/JPL, the IAU or a named paper, and the source list sits below the tool, ready to cite on a slide. An embeddable version is available for school and astronomy sites.

Can I link to one specific planet?
Yes. The page writes all three controls into the address bar, so ?weight=70&unit=kg&body=moon opens on the Moon with 70 kg already filled in. A link carrying only ?body=jupiter still opens on Jupiter, at the default 150 lb, because the weight field falls back to its default when the parameter is absent. An unrecognized body or unit falls back the same way, with no error page.

資料來源與參考文獻

  1. NASA/JPL Solar System Dynamics — planetary physical parameters: equatorial surface gravity in m/s² for all eight planets and Pluto (Mercury 3.70, Venus 8.87, Mars 3.71, Jupiter 24.79, Saturn 10.44, Uranus 8.87, Neptune 11.15, Pluto 0.62), with mean radii and their uncertainties. The four giant planets are quoted at the 1-bar pressure level.
  2. NASA/JPL Solar System Dynamics — satellite physical parameters: GM and mean radius for the Moon (DE440), Io, Europa, Ganymede and Callisto (JUP365), Titan and Enceladus (SAT441) and Triton (NEP097). Every moon's surface gravity on this page is GM ÷ r² from these two published quantities.
  3. NASA/JPL Small-Body Database — Ceres: GM = 62.6284 ± 0.0009 km³/s² and a 939.4 ± 0.2 km diameter, both from the Dawn mission solution (Park et al. 2016, Nature 537:515). Dividing GM by the mean radius those give, 469.7 km, is Ceres's 0.284 m/s²; JPL's own dwarf-planet table divides by the 482.1 km equatorial radius of a 482 × 482 × 446 km body instead and prints 0.27.
  4. Holler, Grundy, Buie & Noll 2021, Icarus 355:114130 — Dysnomia's orbit refitted from seven Hubble orbits: a 15.785899 ± 0.000050 day period that puts the Eris system's mass at (1.6466 ± 0.0085) × 10²² kg. Weighing a body by watching its moon gives the mass of the system, so this is the larger of the two numbers behind the Eris row.
  5. Brown & Butler 2023, PSJ 4:193 — ALMA looking for the wobble Dysnomia induces on Eris and finding only an upper limit: a Dysnomia/Eris mass ratio below 0.0085, i.e. a moon of about 8.2 × 10¹⁹ kg. Subtracting it from the system mass leaves Eris alone, which is what a scale standing on Eris would actually feel.
  6. Brown & Schaller 2007, Science 316:1585 — the first weighing of Eris, from Dysnomia's 37,350 km orbit and 15.774-day period: (1.67 ± 0.02) × 10²² kg. Superseded by the 2021 Hubble refit above and listed because it is where the widely-quoted 0.82 m/s² comes from; this page prints 0.81.
  7. Sicardy et al. 2011, Nature 478:493 — Eris measured by the shadow it cast over Chile on 6 November 2010: a radius of 1,163 ± 6 km, close enough to Pluto's to end the "tenth planet" argument. With the mass above it gives the 0.81 m/s² of the Eris row.
  8. NASA NSSDC Planetary Fact Sheets — the archive that publishes TWO figures per giant planet, "Gravity (mean, 1 bar)" and "Acceleration (eq., 1 bar)", the second with the planet's oblateness and its own rotation folded in: for Jupiter 25.92 and 23.12 m/s², against the 24.79 this calculator takes from JPL. Three published numbers under one word is why four different Jupiter ratios circulate. (NASA has had the archive offline for maintenance since mid-2025; the link lands on that notice.)
  9. NASA NSSDC fact-sheet notes — NASA's own statement of what "surface" means for a planet with no solid one, and of how its gravity and acceleration rows differ. (Offline for maintenance alongside the fact sheets themselves.)
  10. NIST Special Publication 811, Appendix B.8 — conversion factors, exact ones in boldface: the avoirdupois pound as exactly 0.45359237 kg (International Yard and Pound Agreement, 1959) and standard gravity as exactly 9.80665 m/s².
  11. BIPM, The International System of Units (SI Brochure) — the kilogram as the unit of MASS and the newton as the unit of FORCE, which is the distinction this calculator shows on screen rather than only explaining.
  12. Wikipedia, Gravity of Earth — how far real Earth gravity strays from the defined 9.80665 m/s²: 9.7639 m/s² on Nevado Huascarán in Peru to 9.8337 m/s² at the surface of the Arctic Ocean, about 9.780 at the equator against 9.832 at the poles, and up to 0.3% of apparent weight removed by Earth's rotation at the equator.
  13. Wikipedia, Surface gravity — the 1-bar convention stated verbatim ("For gas giant planets such as Jupiter, Saturn, Uranus, and Neptune, surface gravity is given at the 1-bar pressure level in the atmosphere"), and why surface gravity is undefined for a black hole.
  14. IAU 2015 Resolution B3 (Prša et al. 2016, AJ 152:41) — the exact nominal solar constants R☉ = 6.957 × 10⁸ m and (GM)☉ = 1.3271244 × 10²⁰ m³/s², from which this page derives the Sun's 274.2 m/s² and the neutron-star model's mass.
  15. IAU 2006 Resolution B5, the planet / dwarf-planet / small-body definition — why Pluto, Ceres and Eris are grouped as dwarf planets here. Linked through this summary because iau.org's own resolution PDF returns 404.
  16. Bond et al. 2017, ApJ 840:70 — Sirius B from HST astrometry and spectroscopy: dynamical mass 1.018 ± 0.011 M☉ and radius 0.008098 R☉. The white-dwarf row uses the spectroscopic surface gravity the paper reports, log g = 8.591 ± 0.016 (cgs) → 3.90 × 10⁶ m/s²; the same paper derives log g = 8.629 from its own mass and radius, so even a nearby star we have watched since 1862 is quoted two ways.
  17. NASA Goddard, Imagine the Universe — neutron stars: the mass and radius scale (roughly 1.4 solar masses inside about 10 km) that the modelled row on this page uses, and NASA's own "a sugar cube of this material weighs a billion tons" comparison.
  18. NASA, What Is Microgravity? (Grades 5-8) — why orbit is not the absence of gravity, in NASA's own words: at the space station's altitude "Earth's gravity is about 90 percent of what it is on the planet's surface", and a person who weighed 100 pounds on the ground "would weigh 90 pounds at the top of the ladder". Astronauts float because they are in free fall, not because the pull is gone.
  19. Spatially variable crater morphology on the dwarf planet Haumea (arXiv:2307.05833, 2023) — why Haumea is absent from this calculator: its 3.92-hour spin has stretched it into a triaxial ellipsoid whose effective surface gravity runs from 0.0126 m/s² at the equatorial major axis to 1.076 m/s² at the poles, almost two orders of magnitude, so no single figure would describe the body.

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