🛰️ Orbital Velocity & Period Calculator
Find a satellite’s orbital speed and period from the central mass and orbit radius (v = √(GM/r), T = 2π√(r³/GM)).
Orbital velocity v = √(GM/r)
7672.49 m/s
7.67249 km/s
Orbital period T = 2π√(r³/GM)
5544.93 s
92.4156 min · 1.54026 h
Circular orbit: v = √(GM/r) and T = 2π·√(r³/GM), with G = 6.6743×10⁻¹¹. Defaults are a low Earth orbit (~400 km altitude). 🔒 In your browser.
How the orbital velocity & period calculator works
For a circular orbit, gravity supplies the centripetal force, giving orbital velocity v = √(GM/r) and period T = 2π√(r³/GM), where G is the gravitational constant, M the central mass and r the orbit radius from the centre. Enter the mass (or pick a preset) and radius; the tool returns both.
The r³ in the period is Kepler’s third law. Defaults show a low Earth orbit (~400 km altitude, r ≈ 6,771 km), where satellites travel ~7.7 km/s and circle in ~92 minutes.
Frequently asked questions
How do I calculate orbital velocity?
v = √(GM/r), where G is the gravitational constant, M the central mass and r the orbit radius. For low Earth orbit this is about 7.7 km/s.
How do I find the orbital period?
T = 2π·√(r³/GM) — Kepler’s third law. A low Earth orbit takes roughly 90 minutes; the Moon takes about 27.3 days.
What radius do I use?
The distance from the centre of the central body to the orbit, not the altitude. For Earth, add the planet’s radius (~6,371 km) to the altitude.
Why does a higher orbit move slower?
v = √(GM/r) decreases as r grows, so higher orbits are slower and take longer — geostationary satellites orbit far out and match Earth’s 24-hour rotation.
Does the orbiting object’s mass matter?
No — orbital velocity and period depend only on the central mass and radius, not the satellite’s mass (it cancels out).