Kepler third law is one of the most elegant relationships in astronomy: for anything orbiting the Sun, the square of the orbital period in years equals the cube of the semi-major axis in astronomical units. That clean form lets you find one from the other without ever touching the mass or the gravitational constant. This calculator works both ways. Enter a period in years to get the average orbital distance in astronomical units, or enter a distance to get how many years an orbit takes. It is perfect for checking planets, asteroids and comets in our solar system, or for homework and quick sanity checks. Everything is computed instantly in your browser with no network calls.
Kepler third law is one of the most elegant relationships in astronomy: for anything orbiting the Sun, the square of the orbital period in years equals the cube of the semi-major axis in astronomical units. That clean form lets you find one from the other without ever touching the mass or the gravitational constant.
Yes. Kepler Third Law Calculator is completely free, with no sign-up and no usage limits.
Yes. Kepler Third Law Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Kepler Third Law Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.