Geostationary Orbit Altitude Calculator
A geostationary orbit is one where the satellite's orbital period matches the planet's rotation period, making the satellite appear fixed in the sky. The altitude can be found from Kepler's third law: the orbital radius r = (GM T² / 4π²)^(1/3), and the altitude above the surface is h = r - R, where R is the planet's mean equatorial radius. This calculator uses Earth defaults (GM = 3.986 × 10^14 m³/s², rotation period = 86,164.1 s (sidereal day), radius = 6,378.14 km) but all values are user-editable for any planet.
Geostationary orbit formula
r = (GM T² / (4π²))^(1/3) | h = r - R
Where GM is the planet's gravitational parameter (m³/s²), T is the sidereal rotation period (s), R is the planet's equatorial radius (m), and h is the altitude above the surface. For Earth, h = 35,786 km.
Reference geostationary altitudes
- Earth: 35,786 km altitude, 42,164 km orbital radius
- Mars: approximately 17,032 km altitude (sidereal day = 88,643 s)
- Jupiter: approximately 89,195 km altitude (sidereal day = 35,730 s)
- Venus: has a retrograde rotation with a very long sidereal day (243 Earth days), giving a very high geostationary altitude
- Moon: synchronous orbit altitude is about 88,417 km above the surface
Geostationary orbit: frequently asked questions
What is a geostationary orbit?
A geostationary orbit is a circular orbit in which a satellite's orbital period exactly matches the planet's rotation period. The satellite appears stationary over one point on the equator. For Earth the geostationary altitude is about 35,786 km above the surface.
How is the geostationary radius derived?
From Kepler's third law T² = 4pi² a³ / GM, where T is the orbital period equal to the planet's rotation period. Solving for a: a = (GM T² / 4pi²)^(1/3). Subtracting the planet's radius gives the altitude above the surface.
Why is there only one geostationary altitude?
For a given planet, there is exactly one orbital radius that gives an orbital period equal to the planet's rotation period. This radius is fixed by the planet's mass and rotation rate. There is an infinite number of geostationary positions around the equator, but they all share the same altitude.
Why must geostationary orbits be over the equator?
A satellite appears stationary only if its orbit is in the equatorial plane. An inclined orbit at the geostationary altitude traces a figure-8 path (analemma) when viewed from the ground, because the satellite's north-south component causes it to drift above and below the equator.
What is the geostationary altitude for Mars?
Mars has GM = 4.283 x 10^13 m³/s² and a rotation period of 88,643 s (about 24.62 hours). The geostationary radius works out to about 20,428 km, giving an altitude of about 17,032 km above the Martian surface (Mars radius = 3,396 km).
Official sources
- NIST Reference on Constants: Newtonian constant of gravitation.
- NASA Jet Propulsion Laboratory: Planetary Physical Parameters.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.