Physics

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Circular Earth Orbit Calculator.

Calculate circular-orbit speed, period, and escape speed from central mass and orbital radius.

On-device calculationNo signup
01

Set your values

Results update as you type.

Orbital velocity: 7,672.618887 m/s

Orbital velocity

0.000000m/s
Orbital period: 5,544.84047 s

Orbital period

0.000000s
Orbital period: 1.540233 h

Orbital period

0.000000h
Escape velocity: 10,850.721688 m/s

Escape velocity

0.000000m/s

Results update automatically as you type.

Use Cases

Satellite orbit planning

Determine the required speed and period for a satellite in a circular orbit around Earth or another planet, given the planet's mass and the orbit's radius.

Example: For Earth (mass 5.972e24 kg) at radius 6.771e6 m, speed ≈ 7.67 km/s, period ≈ 5544 s.

Astronomy homework help

Quickly compute orbital parameters for hypothetical or real celestial bodies to verify textbook problems or explore orbital mechanics concepts.

Example: Calculate the orbital speed of a moon around a planet with known mass and orbital radius.

Frequently Asked Questions

What does this calculator compute?
Given a central mass (in kg) and an orbital radius from the centre (in m), it calculates the circular-orbit speed, the orbital period, and the escape speed from that radius.
What units are used for the inputs?
Central mass must be entered in kilograms (kg) and orbital radius from the centre in meters (m). The outputs are in meters per second (m/s) for speeds and seconds for the period.
Is this calculator suitable for any central mass?
Yes, you can use any mass, from small bodies to stars or black holes, as long as you provide the mass in kg and the orbital radius from the centre in meters. It assumes a circular orbit and a spherically symmetric mass distribution.

Tips & Common Mistakes

Tips

  • Ensure the orbital radius is measured from the centre of the central mass, not from its surface. For Earth, add the planet's radius to the altitude.
  • Use consistent units: mass in kilograms and radius in meters. If your data is in other units, convert first.
  • The escape speed is the minimum speed needed to escape the central mass's gravity from that radius; it is √2 times the circular-orbit speed.
  • For a quick check, remember that orbital speed decreases with increasing radius, while period increases.

Common Mistakes to Avoid

  • Using the altitude above the surface instead of the distance from the centre of the central mass.
  • Entering mass in grams or radius in kilometers without converting to kg and meters, leading to incorrect results.
  • Confusing orbital speed with escape speed; they are different values, with escape speed being higher.

Last updated: August 13, 2026