Free online tool
Age and Weight on Other Planets
See how old you would be and what a scale would read on another planet.
A planet’s year depends on its orbit around the Sun, while surface gravity affects what a scale reads. Your mass does not actually change when you travel.
How to use it
- Enter an age in Earth years.
- Enter a familiar Earth weight in pounds or kilograms.
- Choose a planet to compare its orbital year and approximate surface gravity.
Good to know
Planet ages use approximate orbital periods measured in Earth years.
Scale readings use approximate surface-gravity ratios. Gas giants do not have a solid surface, so their values refer to a conventional atmospheric level.
Behind the answer
How this calculator works
Planet age divides Earth age by the planet's orbital period measured in Earth years. The scale-reading estimate multiplies Earth weight by the planet's approximate surface-gravity ratio.
Mass is the amount of matter in an object and does not change merely because gravity changes. Everyday scales measure force and report it in familiar mass or weight units, so the displayed comparison describes what such a scale would approximately read.
Worked example
Mars takes about 1.88 Earth years to orbit the Sun. A 20-year-old would therefore be about 10.6 Martian years old. Mars gravity is roughly 38% of Earth's, so an Earth scale reading of 100 would correspond to about 38 in the same unit.
Assumptions and limitations
- Values are rounded educational approximations.
- Gas giants have no solid surface; their reference gravity is measured at a conventional atmospheric pressure level.
- Local gravity varies slightly with altitude, latitude, and planetary rotation.
Common questions
Would my mass change on another planet?
No. Your mass remains the same, but the gravitational force—and therefore a scale reading—changes.
Why am I younger on some planets?
You are not younger in elapsed time. The number changes because a planetary year has a different length.
Helpful sources
Sources reviewed October 2026.