Planet Gravity Calculator

Calculate your weight on other worlds

Enter your weight to see what you'd weigh on every planet, major moon, and notable exoplanet. Explore how mass and radius determine surface gravity.

How to Use

  1. 1
    Enter your weight on Earth

    Input your body weight in kilograms or pounds. The calculator uses this value as a reference, dividing it by Earth's standard surface gravitational acceleration (9.807 m/s²) to derive your mass, which remains constant regardless of location.

  2. 2
    Select the bodies to compare

    Choose from the eight solar system planets, major moons including the Moon, Titan, Ganymede, Europa, and Io, dwarf planets like Pluto and Eris, and notable confirmed exoplanets with published radius and mass data. Multiple selections display in a ranked comparison table.

  3. 3
    Interpret the weight and gravity values

    The table shows your equivalent weight on each body alongside the surface gravitational acceleration in m/s² and as a fraction of Earth's g. Additional context explains how lower gravity affects physical activities, bone density loss rates, and atmospheric escape velocity for each world.

About

Surface gravity is a fundamental planetary characteristic that shapes atmospheric retention, geological activity, tidal forces, and the biological requirements for any life that might inhabit a world. Newton's law of universal gravitation, combined with precise measurements of planetary masses and radii, allows calculation of surface gravity for every solid body and defined pressure level in the solar system. The formula g = GM/r² distills these properties to a single comparative number.

The diversity of surface gravities across solar system bodies spans more than five orders of magnitude, from the Moon at 1.62 m/s² to Jupiter at 24.79 m/s², with tiny asteroids measuring millimeters per second squared or less. This variation profoundly affects planetary atmospheres: a body must have surface gravity sufficient to prevent light atoms like hydrogen and helium from escaping at thermal velocities over geological time. Mars lost much of its early atmosphere partly because its lower gravity allowed atmospheric escape, a process also influenced by the loss of its global magnetic field.

For human space exploration, understanding the gravitational environment of destination worlds is critical to mission design and crew health planning. The Moon's one-sixth gravity enabled Apollo astronauts to carry heavy spacesuits and samples without exhaustion, but prolonged exposure to any sub-g environment causes physiological deconditioning. Research on the ISS at near-zero gravity provides data for modeling the intermediate Martian case, guiding habitat design, exercise countermeasures, and medical protocols for long-duration surface missions.

FAQ

Why does surface gravity differ between planets of similar size?
Surface gravity depends on both the planet's mass and radius: g = GM/r², where G is the gravitational constant. Two planets of identical radius but different compositions can have very different surface gravities. Uranus and Neptune are similar in size but Neptune is about 18% more massive, giving it higher surface gravity. Venus is slightly smaller than Earth but has 81.5% of Earth's mass, yielding a surface gravity of 8.87 m/s², or 0.904 g. The gas giants Jupiter and Saturn have large radii, which partially offsets their enormous masses in the gravity calculation.
How would lower gravity on Mars affect an astronaut?
Mars has a surface gravitational acceleration of 3.72 m/s², about 38% of Earth's. Long-duration missions on Mars would cause significant physiological adaptation including bone mineral density loss at rates similar to those observed on the International Space Station, though somewhat mitigated by the ability to bear weight through walking. Muscles atrophy more slowly than in microgravity. Cardiovascular deconditioning, fluid shifts toward the upper body, and vision changes associated with intracranial pressure elevation remain concerns. NASA's research programs for ISS are partly designed to understand and mitigate these effects for future Mars surface missions.
What is Jupiter's surface gravity and how is it defined for a gas planet?
Jupiter's surface gravity is defined at the 1 bar atmospheric pressure level, the conventional reference for giant planet surfaces. At this level, Jupiter's gravitational acceleration is approximately 24.79 m/s², or about 2.53 times Earth's. This means a person weighing 70 kg on Earth would experience a weight of about 177 kg on Jupiter. Saturn, despite being less dense than water overall, has a surface gravity at the 1 bar level of about 10.44 m/s², only slightly greater than Earth's, because its enormous equatorial radius partly compensates for its mass.
What is the surface gravity on a neutron star?
Neutron stars are among the most extreme objects in the universe, with surface gravitational accelerations on the order of 10¹¹ to 10¹² m/s², approximately 100 billion times Earth's surface gravity. A typical neutron star has a mass of 1.4 solar masses compressed into a sphere of about 10 kilometers radius. An object that weighs 70 kg on Earth would weigh roughly 7 to 70 billion kilograms on a neutron star's surface. The escape velocity from a neutron star is about one-third to one-half the speed of light, placing them at the boundary of general relativistic effects.
How do exoplanet surface gravities compare to solar system worlds?
Hot Jupiters, giant exoplanets orbiting close to their host stars, can have surface gravities several times Jupiter's depending on their mass and inflation state. Super-Earths, rocky planets between 1 and 10 Earth masses, span a wide range: a 5 Earth mass super-Earth with 1.5 Earth radii would have surface gravity about 2.2 times Earth's. Some detected exoplanets like Kepler-20b have measured gravities exceeding 30 m/s². The diversity of exoplanet surface gravities reflects the wide range of compositions and formation histories in planetary systems throughout the galaxy.