Planet Weight Calculator
Calculate your weight on any planet in the solar system based on surface gravity. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculateYour Weight Across the Solar System
Surface Gravity (m/sยฒ)
Formula
Your weight on any celestial body is proportional to its surface gravity compared to Earth's. Surface gravity (g) is determined by the body's mass and radius: g = GM/rยฒ. Earth's surface gravity is 9.81 m/sยฒ.
Last reviewed: December 2025
Worked Examples
Example 1: Weight on Mars
Example 2: Weight on Jupiter
Background & Theory
The Planet Weight Calculator applies the following established principles and formulas. Astronomy and space science rely on a set of precisely defined physical relationships that allow distances, sizes, motions, and energies of celestial objects to be calculated from observational data. Kepler's three laws of planetary motion, derived empirically in the early seventeenth century, describe elliptical orbits, equal areas swept in equal times, and the harmonic law Tยฒ = aยณ, where T is the orbital period in Earth years and a is the semi-major axis in astronomical units (AU). This relationship holds for any object orbiting the Sun and can be generalized using Newton's law of gravitation. Distances in astronomy are expressed in multiple units: one light-year equals approximately 9.461 ร 10ยนโต meters, one parsec equals 3.086 ร 10ยนโถ meters or about 3.26 light-years, defined as the distance at which one AU subtends one arcsecond of parallax. Angular size is calculated as ฮธ = 206,265 ร (d / D) arcseconds, where d is the physical diameter and D is the distance. The stellar magnitude system uses Pogson's formula: m1 โ m2 = โ2.5 ร log10(F1 / F2), where F represents flux. Each magnitude step corresponds to a flux ratio of approximately 2.512, meaning a first-magnitude star is 100 times brighter than a sixth-magnitude star. Hubble's Law relates recessional velocity to distance: v = Hโd, where the Hubble constant Hโ is approximately 70 km/s/Mpc. Escape velocity from any body is given by v = โ(2GM/r), yielding 11.2 km/s for Earth. Orbital period for a circular orbit follows T = 2ฯโ(rยณ/GM). Luminosity and distance are linked by the inverse square law: F = L / (4ฯdยฒ). Stars are classified by spectral type using the mnemonic OBAFGKM, corresponding to surface temperatures from approximately 30,000 K (O-type) to under 3,500 K (M-type). Each type reflects characteristic absorption spectra tied to ionization states of elements in the stellar photosphere.
History
The history behind the Planet Weight Calculator traces back through the following developments. The history of astronomy is one of progressive scale โ each era expanding humanity's conception of the universe's size and structure. The Copernican revolution of 1543, when Nicolaus Copernicus published De revolutionibus orbium coelestium, displaced Earth from the center of the cosmos and placed the Sun at the center of the planetary system. Decades later, Galileo Galilei turned a Dutch-invented telescope toward the sky in 1609, discovering the moons of Jupiter, the phases of Venus, and the cratered surface of the Moon โ observations that provided compelling evidence for the heliocentric model and led to his conflict with the Catholic Church. Johannes Kepler, working from Tycho Brahe's meticulous naked-eye observations, derived his three laws of planetary motion between 1609 and 1619. Isaac Newton unified celestial and terrestrial mechanics with his law of universal gravitation in 1687, explaining the cause behind Kepler's empirical laws and enabling precise prediction of planetary positions. The eighteenth and nineteenth centuries brought systematic sky surveys, stellar parallax measurements, and the discovery that the Milky Way is itself a galaxy among many. Edwin Hubble's 1929 observations using the 100-inch Hooker Telescope at Mount Wilson demonstrated that galaxies are receding from us at velocities proportional to their distance โ the first direct evidence for an expanding universe and the empirical basis for Big Bang cosmology. NASA was founded in 1958 following the Sputnik shock, and the Apollo 11 mission landed humans on the Moon on July 20, 1969. The Hubble Space Telescope, launched in 1990, revolutionized observational astronomy by operating above Earth's atmosphere and producing imagery from ultraviolet to near-infrared wavelengths. The first confirmed exoplanet around a Sun-like star was detected in 1995 by Michel Mayor and Didier Queloz using the radial velocity method. The James Webb Space Telescope, launched in December 2021 and fully operational by 2022, extended infrared observations to probe the earliest galaxies formed after the Big Bang.
Frequently Asked Questions
Formula
Weight on Planet = Earth Weight ร (Planet Surface Gravity รท Earth Surface Gravity)
Your weight on any celestial body is proportional to its surface gravity compared to Earth's. Surface gravity (g) is determined by the body's mass and radius: g = GM/rยฒ. Earth's surface gravity is 9.81 m/sยฒ.
Worked Examples
Example 1: Weight on Mars
Problem: A 70 kg person wants to know their weight on Mars.
Solution: Mars gravity = 3.72 m/sยฒ, Earth gravity = 9.81 m/sยฒ\nRatio = 3.72 / 9.81 = 0.379\nWeight on Mars = 70 ร 0.379 = 26.55 kg-equivalent
Result: 26.55 kg on Mars (37.9% of Earth weight)
Example 2: Weight on Jupiter
Problem: A 150 lb person wants to know their weight on Jupiter.
Solution: Jupiter gravity = 24.79 m/sยฒ, Earth gravity = 9.81 m/sยฒ\nRatio = 24.79 / 9.81 = 2.527\nWeight on Jupiter = 150 ร 2.527 = 379.1 lbs
Result: 379.1 lbs on Jupiter (252.7% of Earth weight)
Frequently Asked Questions
How is a planet's surface gravity calculated?
Surface gravity g = GM/r^2, where G is the gravitational constant (6.674e-11), M is the planet's mass, and r is its radius. Mars has about 38% of Earth's gravity, Jupiter about 253%. Surface gravity affects atmosphere retention, weight, and the energy needed to launch from the surface.
What determines whether a celestial object is a planet, dwarf planet, or asteroid?
Under the IAU definition, a planet orbits the Sun, has enough mass for a nearly round shape, and has cleared its orbital neighborhood of other debris. A dwarf planet meets the first two criteria but has not cleared its orbit (like Pluto). Asteroids are smaller rocky bodies that have not achieved hydrostatic equilibrium.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.
How accurate are the results from Planet Weight Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Why might my result differ from another tool or reference?
Differences typically arise from rounding conventions, the specific version of a formula (for example, simple vs compound interest), or unit inconsistencies between inputs. Check that both tools are using the same formula variant and the same units. The References section links to the authoritative source behind the formula used here.
How do I verify Planet Weight Calculator's result independently?
The Formula section on this page shows the equation used. You can reproduce the calculation manually or in a spreadsheet using those steps. Compare your answer against the worked examples in the Examples section, which use known reference values so you can confirm the calculator is behaving as expected.
References
Reviewed by Daniel Agrici, Founder & Lead Developer ยท Editorial policy