Kepler's Third Law Calculator

Kepler's Third Law: Kepler's Third Law, also known as the "law of harmonies," describes the relationship between the orbital period of a planet and the characteristics of its orbit. It states that the square of the orbital period (T) of a planet is directly proportional to the cube of the semi-major axis (a) of its orbit, and inversely proportional to the mass (M) of the central body. To use the calculator, input the Semi-major axis (AU) and mass, then click the Calculate button!

Semi-major Axis (AU) Mass (solar masses) Calculate

Developer Notes:

• The calculator assumes circular orbits and that the planet's mass is much smaller than the central body's mass (usually true for planets orbiting stars).
• Kepler's Third Law is a simplified model and may not apply to highly eccentric orbits or systems with significant gravitational interactions.