Planets - Calculate Circular Velocity
Calculator for the circular velocity or first cosmic velocity of objects like satellites around Earth, Moon, Sun and planets. The circular velocity is the speed an object must have to fly around a celestial body in a low, circular orbit. If the speed is lower, the object can fall down, if it is higher, the orbit will become elliptical, until it reaches the second cosmic velocity, the escape velocity. The cosmic velocities depend on mass and diameter of the celestial body, things like air friction are not taken into account. For higher orbits, the velocity gets lower.
Round to decimal places.Please enter one value, the other values will be calculated.
Example: the International Space Station ISS has a velocity of approximately 27600 km/h. This value is slightly lower than the circular velocity of Earth, because ISS has a height of about 400 kilometers.
The formula for calculating orbital velocity is
The theoretical orbital velocity, or first cosmic velocity cited here refers to an orbit at a distance from the center equal to the planet's radius, meaning, for a rocky planet, an orbit right at the surface. Such an orbit is, of course, impossible for Earth, given the presence of an atmosphere that causes drag, as well as obstacles at that altitude such as mountains, buildings, and the like. Other rocky planets and moons also feature surface elevations. Gas planets do not. However, the radius of a gas planet is typically defined by the layer where the pressure equals one bar. In the case of Jupiter for instance, with an orbital velocity exceeding 150,000 kilometers per hour, atmospheric resistance during such an orbit would be immense.
Last updated on 08/08/2026. Author: Jürgen Kummer
Calculators for Planets and Astronomy
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