Orbital Period Calculator

Kepler's Third Law

Calculate orbital period and velocity for satellites and celestial bodies using Kepler's Third Law.

Orbital Parameters

km

Distance from center of central body to orbit

Kepler's Third Law

T = 2Ο€βˆš(aΒ³/GM)

where: T = period, a = semi-major axis, G = gravitational constant, M = central body mass

Note

This calculator assumes circular orbits. For elliptical orbits, the semi-major axis is the average of the closest and farthest distances.

Example Orbits

ISS (Earth)
~6,800 km β†’ 92 min
Geostationary (Earth)
42,164 km β†’ 24 hours
Moon (Earth)
384,400 km β†’ 27.3 days
Earth (Sun)
149,600,000 km β†’ 365 days

About Orbital Mechanics

Kepler's Third Law states that the square of the orbital period is proportional to the cube of the semi-major axis.

  • Period depends on distance and central mass
  • Closer orbits have shorter periods
  • Independent of satellite mass

Applications

  • Satellite orbit design
  • Space mission planning
  • GPS satellite positioning
  • Planetary motion prediction
  • Exoplanet discovery