Orbital Velocity and Period Calculator
Newton's Law of Gravitation:
mv2/r = GMm/r2

We can easily re-arrange this and solve for v to get:

v = sqrt(GM/r)

Enter the orbit altitude in km, then click
 
Altitude (km)
Orbital Velocity (km/s)
Period (min)
Note: this calculator is only valid assuming circular earth orbits
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