Your weight on another planet equals your Earth weight multiplied by that planet's gravitational acceleration divided by Earth's: W_planet = W_Earth × (g_planet / g_Earth), using NASA/JPL equatorial gravity values. Mass does not change when you travel to another planet; weight does, because weight is the force produced by gravity acting on your body. NASA's W = mg relationship makes it possible to compare one Earth scale reading against Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune with a single ratio. The Weight on Other Planets Calculator applies this ratio using the published equatorial surface gravity values for each planet and shows the result in the unit label you select. Because the underlying ratio is unitless, an Earth reading of 100 can be displayed in pounds, kilograms, newtons, or a custom label and still produce the same numeric comparison. The figures are educational approximations that assume equatorial surface conditions, not local values that vary with latitude, altitude, rotation, and geology. To use the comparison correctly, remember that the table describes gravitational pull, not a change in how much matter is in your body.
Why Mass and Weight Behave Differently on Other Planets
Mass and weight are two physical quantities that beginners routinely swap. Mass measures how much matter an object contains, and it stays the same whether you stand in your kitchen, on the Moon, or in orbit around Neptune. Weight is the force that gravity exerts on that mass, so it changes whenever the local gravitational acceleration changes. NASA expresses this relationship with the familiar equation W = m × g, where W is weight, m is mass, and g is gravitational acceleration. The same equation is restated in NASA's beginner guide to aeronautics as the standard relationship between force, mass, and gravity.
Because the acceleration term is the only piece that varies between planets, a single ratio captures the entire comparison. If you know your scale reading on Earth (W_Earth) and you know the equatorial gravity of another planet (g_planet), you can find the equivalent reading (W_planet) by multiplying: W_planet = W_Earth × (g_planet / g_Earth). This is the equation that the calculator applies eight times, once for each planet in the solar system, so the work reduces to looking up one number per row.
One subtle point is worth noting before you run the numbers. A bathroom scale labeled "kilograms" is not measuring mass directly; it is measuring the force your body exerts under Earth's gravity and converting that force into kilograms using a built-in value of g. If you type "100 kg" into the calculator, the tool is showing what a familiar kilogram-labeled scale would read under each planet's gravity, not that your body suddenly contains a different amount of matter. Pounds and newtons are force units in the same way, so the displayed label tells you what kind of reading you are seeing, not what physical quantity has changed.
The NASA/JPL Gravity Values Behind the Comparison
The numbers in the comparison table come from the NASA/JPL Solar System Dynamics reference for planetary physical parameters. The eight equatorial surface gravity values, in meters per second squared, are listed below.
| Planet | Equatorial surface gravity (m/s²) |
|---|---|
| Mercury | 3.70 |
| Venus | 8.87 |
| Earth | 9.80 |
| Mars | 3.71 |
| Jupiter | 24.79 |
| Saturn | 10.44 |
| Uranus | 8.87 |
| Neptune | 11.15 |
Two things stand out in the table. First, Mars and Mercury have nearly identical gravity, even though Mars has roughly twice Mercury's mass; both radius and density affect surface gravity, so the two numbers do not track each other in a simple way. Second, Jupiter's gravity is more than twice Earth's, which is why NASA's familiar educational examples show that an Earth reading of 100 becomes about 253 on Jupiter. Source: NASA/JPL Planetary Physical Parameters.
How to Use the Weight on Other Planets Calculator
- Enter a positive scale reading measured on Earth. Use the unit you normally see on your bathroom scale so the comparison feels familiar.
- Choose a display label (pounds, kilograms, newtons, or a custom unit) so the table header matches the unit you want to compare.
- Select Compare planetary weight to generate the eight-planet table.
- Read each row alongside the planet's equatorial gravity. The Earth row should equal the number you entered; use that as an immediate sanity check before looking at the others.
- Remember that mass stays constant. The comparison shows gravitational pull, not a change in the amount of matter in your body, and the figures are educational approximations rather than local measurements.
The Weight on Other Planets Calculator handles the multiplication internally using the JPL values listed above, so you only need a single input to see all eight rows. All processing happens inside the current browser tab, and changing the input clears the previous table so a stale comparison cannot be mistaken for a fresh one.
Worked Example: Reading 100 on Earth, Compared to Mercury
Take an Earth reading of 100 and ask what the same object would weigh on Mercury. Using the formula W_planet = W_Earth × (g_planet / g_Earth):
W_Mercury = 100 × (3.70 / 9.80) W_Mercury = 100 × 0.3776 W_Mercury ≈ 37.76, which the calculator displays as roughly 38.
This matches NASA's educational anchor that an Earth reading of 100 is roughly 38 on Mercury. The same arithmetic for Jupiter gives 100 × (24.79 / 9.80) ≈ 252.96, displayed as about 253, which is the second NASA anchor that students often see. Because the multiplication factor for Mercury is about 0.38 and for Jupiter about 2.53, you can estimate any planet's reading by multiplying your Earth value by the planet's gravity ratio. The calculator does this for all eight planets at once, so you do not need to repeat the arithmetic by hand.
What the Calculator Does Not Include
The tool is built for a specific job: educational comparison against the eight IAU-recognized planets using equatorial surface gravity. Several common follow-up questions fall outside its scope, and it is worth listing them so you know when to reach for a different resource.
- Moons, dwarf planets, and asteroids. The Moon, Pluto, Ceres, and small bodies are not in the comparison. For lunar readings you would need a separate surface-gravity value, often listed as about 1.62 m/s².
- Exoplanets and stars. The table covers only the eight planets of our solar system, so any Earth-like planet around another star is out of scope.
- Local variations of gravity. Real effective gravity depends on latitude, altitude, rotation, and local geology. The JPL equatorial value is a single reference number, not a universal value at every location.
- A solid surface for gas and ice giants. Jupiter, Saturn, Uranus, and Neptune do not have a place where a person could stand. The published gravity refers to a defined reference level inside the atmosphere, often taken at a pressure level close to one bar.
- Escape velocity, orbital weight, and free fall. These are separate physics problems that need additional inputs such as orbital radius or drag, which the tool does not model.
- Engineering and mission analysis. For real spacecraft work, use the body-specific gravity model, the reference ellipsoid, altitude, and the uncertainty required by the project rather than an educational approximation.
The calculator also is not a health, fitness, or dosing tool, even if the starting number came from a bathroom scale. For a fuller conceptual walkthrough that compares mass and weight definitions, the related guide on how to calculate mass on another planet extends the same physics with additional classroom framing.
Quick Reasonableness Checks Before You Trust a Row
Any tool that produces a table invites sloppy reading. A few quick checks will help you decide whether each row is plausible before you copy a number into a homework answer or a presentation slide.
- The Earth row must equal the entered reading. If you typed 70 and the table shows 69 or 71, something is off and you should re-enter the input.
- Mercury should be around 38% of the Earth value. JPL's gravity ratio of 3.70 / 9.80 ≈ 0.378, so an Earth reading of 200 should land near 76 on Mercury.
- Jupiter should be around 253% of the Earth value. The ratio 24.79 / 9.80 ≈ 2.53 is the highest in the table, so Jupiter is always the largest row.
- Venus and Uranus share the same gravity value to the published precision. 8.87 m/s² appears twice in the JPL table, which is unusual and worth noticing when you scan the columns.
- Mars should sit very close to Mercury. Both values are near 3.7 m/s², so their rows will track each other within roughly a tenth of a percent.
NASA's Space Place article on weighing planets is a good companion read if you want to see the same comparison presented in a classroom context. For classroom work, the JPL table is the citation that anchors any of the numbers above, and the comparison should always be described as using equatorial surface gravity rather than a single global value.