Earth Orbit Calculator

Circular Orbit Velocity and Period

For a satellite in a stable circular orbit, gravitational force provides exactly the centripetal force needed to maintain the orbit, which gives orbital velocity v = √(GM/r), where GM is Earth’s standard gravitational parameter (about 3.986×10¹⁴ m³/s²) and r is the orbital radius measured from Earth’s center.

The orbital period follows from Kepler’s third law as T = 2π√(r³/GM). Low Earth orbit satellites (a few hundred km up, like the ISS) travel at roughly 7.7 km/s and complete an orbit in about 90 minutes, while geostationary satellites at about 35,786 km altitude match Earth’s rotation with a 24-hour period.