Weight on Other Planets
See what you'd weigh across the Solar System — from the Moon to Jupiter and the Sun — based on real surface-gravity data.
Age on Other Planets
Convert your Earth age into planetary years using each planet's real orbital period. A fun, shareable way to see the scale of the Solar System.
Satellite Orbit Calculator
Enter an altitude to get the orbital period, speed and orbits per day — with ISS and geostationary presets.
Free online space calculators — private by design
Quick, dependable tools for space enthusiasts, students and satellite geeks: find your
weight on other planets, your age on other planets, and a real
satellite orbit calculator. Everything runs locally in your browser — no sign-ups,
no uploads — so they're instant whether you're at a desk or on your phone.
Frequently asked questions
How much would I weigh on other planets?
Your weight scales with each body's surface gravity. Enter your weight and the calculator shows it on the Moon, Mars, Jupiter and more — e.g. on the Moon you weigh about 16.6% of your Earth weight, and on Jupiter about 2.36× as much. Your mass never changes; only weight (the pull of gravity) does.
How is my age different on other planets?
A "year" is one orbit around the Sun, and every planet orbits at a different speed. Mercury races around in 88 days, so you'd be much "older" there; Neptune takes ~165 Earth years, so you'd be less than one Neptune year old. Enter your Earth age to see all of them.
How do I calculate a satellite's orbital period?
For a circular orbit, T = 2π√(a³/μ), where a is the orbit radius (Earth's radius + altitude) and μ = 3.986×10¹⁴ m³/s² is Earth's gravitational parameter. The Satellite Orbit tool also gives orbital speed and orbits per day. The ISS (~400 km) circles Earth in about 92 minutes; a geostationary satellite (~35,786 km) takes exactly one day.
Are these space calculators free and private?
Yes — every tool is 100% client-side JavaScript. No signup, nothing is uploaded, and your inputs never leave your device. They work on mobile and desktop and keep working offline once the page has loaded.