Orbital velocity calculator
Enter the orbit height above the surface to see the speed needed to stay in a circular orbit and how long one lap takes.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter body and orbit height above surface.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
v = √(GM ÷ r) and T = 2πr ÷ v, where r is the body's mean radius plus the orbit height.
Example
Inputs: Body = Earth, Orbit height above surface = 400 km. Result: Orbital speed: 7.673 km/s; In kilometres per hour: 27,621 km/h; Orbital period: 92.41 min.
Limits and caveats
- Circular orbits only; in an elliptical orbit the speed changes along the path.
- Atmospheric drag in very low orbits is not included.
Questions about this tool
How fast does the ISS travel?
At about 400 km it moves near 7.67 km/s and completes an orbit in about 92 minutes.
Why are high satellites slower?
Gravity is weaker farther out, so a lower speed is enough to balance it.
What is the height of a geostationary orbit?
About 35,786 km above the equator, with a period of one sidereal day.