Orbital Velocity and Period Calculator
Works out how fast something must go to stay in a circular orbit.
Orbital velocity
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In km/s — km/s
Orbital period —
Period in minutes — min
Orbit radius, from the centre —
Assumes —
The formula
v = √(GM ÷ r) T = 2π√(r³ ÷ GM)
r is measured from the centre of the body, so it is the body’s radius plus the altitude. The satellite’s own mass cancels out.
What to watch out for
Higher orbits are slower and take longer. For elliptical orbits, this speed applies only at a single average radius.
Frequently Asked Questions
How fast does a satellite orbit at 400 km?
Around Earth, about 7.67 km/s, taking 92.4 minutes per orbit.
What altitude gives a 24-hour orbit?
About 35,800 km gives 23.9 hours. A geostationary orbit matches the sidereal day of about 23.93 hours.