Weight & Age on Other Planets

About the Weight & Age on Other Planets

Your mass is the same everywhere, but your weight — the pull of gravity on you — depends on where you stand. Enter what your scale shows on Earth and this calculator shows what the same scale would read on the Moon, on each planet, on Pluto, on the largest moons of Jupiter, Saturn, Neptune and Pluto, and at the surface of the Sun, together with the force in newtons and how high the same jump would take you. The gravity values come from NASA’s planetary fact sheets.

Add your birth date to see how old you are in Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto years — a year being one trip around the Sun — and the date of your next birthday on each planet. A bar chart makes the comparison easy to see for children and classes.

Common uses

• Science lessons on gravity, weight and mass for children and teenagers.
• Showing the difference between weight (a force, in newtons) and mass (in kilograms).
• Fun facts for birthdays: your age and next birthday on Mars or Jupiter.
• Quick reference values for the surface gravity of planets and large moons.

Weight, mass and what your scale shows

A bathroom scale measures the force you press down with and displays it as kilograms, assuming Earth’s gravity. On another world the same scale would show your Earth reading × (gravity there ÷ gravity on Earth); that is the “scale reading” here. The true weight is a force: W = m × g, in newtons. Your mass m does not change.

Bodies without a solid surface (the Sun and the giant planets) have no ground to stand on: their values are for the Sun’s visible surface and for the level in the giant planets’ atmospheres where the pressure is 1 bar, as NASA gives them.

Gravity values used (m/s²)

• At the equator, including the planet’s spin (NASA’s “Gravity” row; default): Mercury 3.70 · Venus 8.87 · Earth 9.78 · Moon 1.62 · Mars 3.69 · Jupiter 23.12 · Saturn 8.96 · Uranus 8.69 · Neptune 11.00 · Pluto 0.62 · Sun 274.0.
• Mean surface gravity, without spin: Earth 9.82 · Mars 3.73 · Jupiter 25.92 · Saturn 11.19 · Uranus 9.01 · Neptune 11.27; the others are the same as above.
• Moons, from g = GM/r² with NASA’s masses and radii: Io 1.80 · Europa 1.32 · Ganymede 1.43 · Callisto 1.24 · Titan 1.35 · Triton 0.78; Charon 0.29 (NASA).

Fast-spinning planets differ most: on Jupiter you would weigh 2.36 times your Earth weight at the equator but 2.64 times on average without the spin — which is why other sites quote different figures. NASA’s overview table rounds Pluto to 0.7 m/s²; its Pluto fact sheet gives 0.62.

Age on other planets

A planet’s year is one orbit of the Sun. Your age there is the number of days you have lived divided by the length of its year in Earth days: Mercury 87.968, Venus 224.695, Earth 365.242, Mars 686.972, Jupiter 4,330.595, Saturn 10,746.94, Uranus 30,588.74 and Neptune 59,799.9 days (tropical years), and Pluto 90,560 days (its sidereal period, as its tropical year is not well known). Your next birthday on a planet is the day on which your age there reaches the next whole number. On Earth the calendar birthday is used.

Sources

• NASA Space Science Data Coordinated Archive (NSSDCA), Planetary Fact Sheet and the fact sheets of each planet, Pluto, the Moon and the Sun (Dr David R. Williams): surface gravity and acceleration, orbital periods.
• NSSDCA Jovian, Saturnian and Neptunian satellite fact sheets: masses and radii of the moons.
• NIST, CODATA value of the Newtonian constant of gravitation: G = 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻². NIST, Guide to the SI, appendix B.9: 1 lb = 0.45359237 kg exactly.

Limitations

• Gravity varies over each world’s surface with latitude, height and local geology; the values are the standard reference figures, not what you would measure at one spot.
• You could not actually stand on the Sun, Jupiter, Saturn, Uranus or Neptune — the numbers are for their visible surface or 1-bar level.
• Jump heights ignore air resistance and assume the same take-off speed; a space suit would change both.
• Ages count whole days between dates in your own calendar and do not adjust for the time of day you were born.

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