Space Calculators

Every live calculator is unit-tested against known values (for example, Earth's escape velocity of 11.19 km/s). Planned tools are honestly labelled — no fake buttons.

Planets

Weight on Other Planets

Your mass never changes — your weight does. See what a scale would show on each planet.

Tested & live

Age on Other Planets

A year is one orbit. Count your birthdays on Mercury, Mars, Jupiter and beyond.

Tested & live

Escape Velocity Calculator

How fast must something go to leave a planet forever, never to fall back?

Tested & live

Planet Density Calculator

Mass divided by volume reveals what a world is made of — rock, gas, or ice.

Tested & live

Planet Rotation Speed

How fast does the ground move beneath you at the equator?

Tested & live

Distance & Light

Light Travel Time

Light is fast, but space is bigger. Find how long light takes to cross any distance.

Tested & live

Space Distance Converter

Convert between kilometres, AU, light-years and parsecs — the rulers of astronomy.

Tested & live

Orbital Mechanics

Orbital Period (Kepler's Third Law)

Bigger orbits take longer — predict a year anywhere with Kepler's law.

Tested & live

Orbital Velocity Calculator

How fast must a spacecraft travel to stay in a circular orbit?

Tested & live

Ideal Rocket Equation (Delta-v)

Tsiolkovsky's equation: why rockets are mostly fuel.

Tested & live

Astronomy

Telescope Magnification

Divide telescope focal length by eyepiece focal length. Simple — and often misused.

Tested & live

Black Hole Schwarzschild Radius

Squeeze any mass small enough and it becomes a black hole. Find that size.

Tested & live

Stellar Parallax Distance

The original cosmic ruler: measure a star's tiny yearly wobble, get its distance.

Tested & live

Stellar Luminosity Calculator

Bigger and hotter stars shine brighter — by the fourth power of temperature.

Tested & live

Planet Equilibrium Temperature

Estimate a planet's temperature from starlight alone — then see why atmospheres matter.

Tested & live

Advanced Physics

Mass–Energy Equivalence (E = mc²)

Einstein's famous equation: how much energy is locked inside mass?

Tested & live

Time Dilation Calculator

Move fast and time slows down. Calculate the Lorentz factor for any speed.

Tested & live

Hubble-Law Distance Estimator

The universe is expanding: faster recession means farther away.

Tested & live

Planned (not yet built)

Solar System Scale Model — planned, not implemented yet
Hohmann Transfer Estimator — planned, not implemented yet
Angular Resolution — planned, not implemented yet
Telescope Light-Gathering Power — planned, not implemented yet
Redshift & Wavelength — planned, not implemented yet
Gravitational Time Dilation — planned, not implemented yet
Exoplanet Transit Depth — planned, not implemented yet
Surface Gravity from Mass & Radius — planned, not implemented yet