Orbital Period Calculator
Calculate the time it takes for a satellite or planet to complete one circular orbit around a central body.
What determines orbital period
For a body in a circular orbit, the orbital period depends only on the mass of the central body and the orbital radius, following T = 2π√(r³ / GM), where G is the gravitational constant (6.674 × 10-11 N·m²/kg²), M is the central body’s mass, and r is the orbital radius measured from the center of the central body.
How this calculator works
Enter the mass of the central body (such as Earth or the Sun) and the orbital radius of the object circling it. The calculator applies the circular orbit formula to find the period in seconds, and also converts the result to hours and minutes for convenience.
This formula assumes a perfectly circular orbit and that the orbiting object’s own mass is negligible compared to the central body — a very good approximation for satellites, moons, and planets. This calculator is for general astronomy education and planning purposes.