Orbital Period Calculator
Estimate the orbital period of a satellite or planet using Kepler's third law. Provide the semi-major axis in meters and the central body's mass in kilograms to see how long one full revolution takes.
CalcSimpler Examples
- 1.496e11 m around 1.989e30 kg (Earth around Sun) ⇒ 31,558,149 s
- 6.78e6 m around 5.972e24 kg (ISS orbit) ⇒ 5,550 s
- 3.84e8 m around 5.972e24 kg (Moon) ⇒ 2,360,592 s
FAQ
Can I input kilometers?
Convert kilometers to meters before entering values.
Does it account for orbital eccentricity?
No, it assumes a circular orbit for simplicity.
What is the central mass?
It is the mass of the body being orbited, such as a planet or star.
How accurate is the gravitational constant used?
The calculator uses the CODATA 2018 value of G (6.67430×10⁻¹¹ m³/kg·s²). Minor updates to G have little effect on most orbital estimates.
Additional Information
- The formula is T = 2π × √(a³ / μ) where μ = G × M and G = 6.67430×10⁻¹¹ m³/kg·s².
- Results are in seconds. Divide by 3,600 for hours or by 86,400 for days.
- Assumes an ideal two-body system with negligible eccentricity.
- Perturbations from other bodies, drag, or relativity can slightly alter real orbital periods.
CalcSimpler