What Would You Weigh on Other Planets? A Tour of Gravity Across the Solar System

When the Apollo 11 astronauts bounced across the lunar surface in 1969, they weighed about one-sixth of what they did on Earth. Neil Armstrong, roughly 160 pounds in his spacesuit on the launch pad, felt like he weighed just 27 pounds on the Moon. He could jump several feet high with minimal effort while carrying a life-support backpack that would have been exhausting on Earth.

Gravity is the invisible hand that shapes everything from how tall trees can grow to whether a planet can hold onto an atmosphere. And it varies wildly across our solar system -- which means your weight, measured in any unit, changes depending on where you stand.

What Determines a Planet's Gravity

Surface gravity depends on two factors: mass and radius. A more massive object pulls harder. But a larger radius puts you farther from the center of mass, which weakens the pull. The formula is straightforward:

g = GM / r squared

Where G is the gravitational constant (6.674 times 10 to the negative 11th), M is the planet's mass, and r is its radius.

This relationship produces some counterintuitive results. Saturn is 95 times more massive than Earth, yet its surface gravity is only 7% stronger. Why? Because Saturn is enormous and made mostly of hydrogen and helium, so its "surface" (really the cloud tops) sits very far from its center.

Your Weight on Every Planet

Here is what a 150-pound (68 kg) person would experience across the solar system. You can verify any of these conversions with our pounds to kilograms converter.

On Jupiter, that 150-pound person would feel like they weigh 380 pounds. Standing up would be a struggle. Climbing stairs would feel like carrying another full-grown adult on your back.

The Mars-Mercury Coincidence

Mars and Mercury have identical surface gravity at 0.38g despite being radically different worlds. Mercury is tiny (about 38% of Earth's diameter) but incredibly dense. Its iron core makes up roughly 85% of the planet's radius, giving it unusual heft for its size. Mars is nearly twice Mercury's diameter but composed of lighter silicate rock and has a small core. The result: same gravity at the surface, for completely different reasons.

Moons Worth Visiting

Earth's Moon sits at 0.166g, or about one-sixth of Earth's gravity. That is enough to walk on, though every step becomes a slow-motion bound.

Some of the solar system's moons would offer even stranger experiences:

On Titan, the combination of low gravity and a thick nitrogen atmosphere (1.5 times Earth's surface pressure) means a person wearing strap-on wings could genuinely fly under their own muscle power, according to calculations by physicists at the Lunar and Planetary Institute.

The Sun and Gravitational Extremes

The Sun's surface gravity is 28 times Earth's. A 150-pound person would weigh 4,200 pounds, roughly the mass of an SUV. Your bones would shatter instantly. Of course, the 5,500 degree Celsius surface temperature would vaporize you long before gravity became your problem.

Neutron stars occupy the other end of the scale. These collapsed stellar remnants pack 1.4 solar masses into a sphere about 12 miles across. Surface gravity reaches roughly 200 billion g. A marshmallow dropped onto a neutron star would hit with the energy of a small nuclear weapon.

What Low Gravity Does to the Human Body

NASA has decades of data on what reduced gravity does to astronauts, and the news is not great for future Mars colonists. In microgravity, bones lose 1-2% of their density per month -- a rate comparable to severe osteoporosis. Muscles atrophy without resistance. Fluids shift toward the head, causing facial puffiness, reduced leg volume, and increased intracranial pressure that can damage vision.

Astronauts on the International Space Station exercise for over two hours daily to slow these effects. Mars colonists would face a milder version of the same problems at 0.38g. We do not yet know whether Mars gravity is enough to prevent long-term bone loss because nobody has lived in partial gravity for extended periods. It is one of the biggest open questions in space medicine.

The force of gravity on your body is measured in newtons. To convert between familiar weight units and newtons, use our kg to newtons converter. If you need to switch between metric and imperial weight, our kilograms to pounds converter handles that as well.

Gas Giants: No Ground to Stand On

The gravity values listed for Jupiter, Saturn, Uranus, and Neptune are measured at the altitude where atmospheric pressure matches Earth's sea level (1 bar). There is no solid surface. Below that reference point, you would sink into increasingly dense layers of gas that gradually transition to liquid and eventually to exotic high-pressure states. Jupiter's core pressure is estimated at 40 million times Earth's atmospheric pressure.

Key Takeaways

Jupiter has the strongest planetary gravity at 2.53g. Mars and Mercury share the same surface gravity (0.38g) for entirely different structural reasons. Saturn's gravity barely exceeds Earth's despite being 95 times more massive. Extended time in low gravity causes serious health effects that remain an unsolved problem for long-duration space missions. And the Sun's gravity would crush you -- assuming the heat did not get you first.