Earth Orbit Calculator

Use our earth orbit calculator to find the velocity or period of an earth satellite, given its height above sea level:

• Calculating the orbital speed of a satellite is crucial to keep it orbiting around the earth and avoid it flying away from earth, or even worse, crashing against it. The resulting momentum of this speed, combined with gravity force, makes possible this orbital movement.
• Additionally, calculating the orbital period of an earth's satellite is necessary to know its position at any moment.

Keep reading to learn more about the formulas used by this tool to calculate satellite velocity and period.

With the following formula, you can calculate the velocity of a satellite orbiting the earth in a circular orbit:

where:

• $G$ – Earth's gravitational constant;
• $M_\text{E}$ – Earth's mass;
• $R_\text{E}$ – Earth's radius; and
• $h$ – Perpendicular distance of the satellite from the surface of the earth.

The previous formula is used by this earth orbit calculator when choosing the "Speed of the satellite" option. If you enter the height of the object spinning the earth, the calculator will account for the earth's mass, radius, and gravitational constant and will give you the satellite velocity.

To calculate the orbital period of an earth's satellite, use this formula:

The previous one is also the formula used by this calculator. In the earth orbit calculator, select the "Period of satellite rotation" option and input the object's height. You'll have the answer without worrying about the earth's mass, radius, and gravitational constant.

Let's calculate the orbital speed of the International Space Station (ISS):

• We know the ISS orbits at 400 km above the earth's surface.
• Select the "Speed of the satellite" option and input 400 km in the "Height" box. The obtained orbital speed should be 7.672 km/s.

Do you wonder how fast an object would fall from high heights? Check the terminal velocity formula to see how air resistance can limit the final speed!