🪐 How Much Would You Weigh on Every Planet?

Mini glossary

• Mass (kg): How much matter you have. Same everywhere.
• Weight (N): The force due to gravity: mass × g. Changes from world to world.
• Surface gravity (g): Acceleration an object feels at a world’s “surface.”
• kgf: Kilogram-force. The force exerted by 1 kg under Earth gravity (~9.80665 N).

How we figure it out (short version)

Weight is a force (Newtons) caused by gravity. Your mass stays the same everywhere, but weight changes with the local surface gravity g.

Earth mass (kg) from your input:
- If you enter Earth weight in kg (a scale reading): mass ≈ kg_value
- If you enter Earth weight in lb: mass ≈ lb × 0.45359237
- If you enter Earth weight in N: mass ≈ N ÷ g_earth
- If you enter mass (kg): mass = kg

Weight on a world = mass × g_world   (in Newtons)
Earth-relative weight factor = g_world ÷ g_earth

We use standard surface gravity values based on mean radii and mass. Real bodies vary slightly with latitude and altitude.

Gravity 101: why your “weight” changes but your mass doesn’t

On Earth, most bathroom scales show kilograms, but they’re really reporting how much force your body exerts on the scale under Earth’s gravity. That’s why this tool lets you enter either Earth weight (kg, lb, or N) or your mass in kilograms. Your mass is an amount of “stuff” and it doesn’t change when you travel; what changes is the local g, the strength of gravity at the surface of another world.

Surface gravity depends on two things: the world’s mass and its radius. A heavier world pulls harder, but a larger radius spreads that pull over a bigger distance. This is why Saturn (huge but puffy) has surface gravity only a bit stronger than Earth’s, while Jupiter (even denser) produces a much bigger pull. Small rocky bodies like the Moon or Ceres can only tug a little, so you’d feel almost “bouncy” there.

Quick example with a 40 kg person:

• Earth: 40 × 9.80665 ≈ 392 N (this is your everyday weight).
• Moon: 40 × 1.62 ≈ 65 N (about one-sixth of Earth).
• Jupiter: 40 × 24.79 ≈ 992 N (over 2.5× Earth).

Fun takeaway: if you can jump 0.4 m on Earth, you might jump a couple of meters on the Moon—same legs, smaller g!

Common myths

“Bigger planet = always more weight.”

Not always. Radius matters. If a planet is very large and not very dense, the surface can be far from the center, reducing g. That’s why Saturn’s surface gravity is close to Earth’s even though Saturn could fit many Earths inside by volume.

“Kilograms are mass, so my scale is wrong.”

Your scale measures force but labels it in kilograms for convenience—think “kilogram-force.” This tool converts that reading into true mass, then recomputes weight in Newtons for other worlds.

“You could stand on gas giants or the Sun.”

They don’t have solid surfaces. “Surface gravity” is a standard reference value, useful for learning and comparisons—not an invitation to land there.

Try these comparisons

• Earth vs. Mars: Astronaut training staple—Mars is ~0.38× Earth’s gravity, so walking feels lighter but not floaty.
• Earth vs. Moon: About one-sixth gravity explains the Apollo “bunny hops.”
• Earth vs. Neptune: Slightly stronger than Earth; heavy enough to feel different, not enough to flatten you.
• Pluto or Ceres: Tiny gravity means careful landings and superhero jumps.

Tip: switch the calculator to Mass mode if you know your exact kilograms. The results list shows Newtons plus an Earth multiplier (e.g., “0.38× Earth” for Mars), which is perfect for classrooms and quick demos.

Space safety 💛

• Gas giants and the Sun don’t have solid surfaces to stand on. Their listed “surface gravity” is a standard reference for learning.
• On airless bodies, you’d need a spacesuit and a gentle landing!