Orbital Period Calculator

Find the period of a circular orbit (Kepler's third law).

Central body mass

Orbit radius

Period 31,554,896.93

Period (days) 365.22

Period (years) 0.9999

Formula: T = 2π√(r³ ÷ GM)

Step-by-step with your numbers:

1. Values used:

2. Central body mass = 1.989e+30

3. Orbit radius = 149,600,000,000

5. Period = 31,554,896.93

6. Period = 365.22days

7. Period = 0.9999years

Did we solve your problem today?

Kepler's third law gives the orbital period from the orbit size and central mass.

The math behind it

T = 2π√(radius³ ÷ GM).

Earth around the Sun → ~365 days.

Bigger orbit?

Longer period — period grows with radius^1.5.