Satellite Orbit Calculator — Altitude, Velocity, and Period for Earth Orbits

There are over 8,000 active satellites orbiting Earth right now. Each follows the same Newtonian physics — the balance between velocity keeping it from falling and gravity pulling it down. Change the altitude and every other orbital parameter shifts with it.

Calculate orbital parameters for any Earth satellite at CalcHub.

The Orbital Mechanics

For a circular orbit around Earth, the orbital velocity is:

v = √(GM / r)

Where G is the gravitational constant, M is Earth's mass (5.97 × 10²⁴ kg), and r is the orbital radius (Earth's radius + altitude).

Orbital period follows directly: T = 2πr / v = 2π√(r³/GM)

Earth Orbit Types

Orbit Type	Altitude	Period	Key Users
Very Low Earth (VLEO)	160–450 km	88–93 min	Spy satellites, some experiments
Low Earth Orbit (LEO)	450–2000 km	93–127 min	ISS, Starlink, Hubble, Earth observation
Medium Earth Orbit (MEO)	2000–35,000 km	2–24 hours	GPS, Galileo, GLONASS navigation
Geostationary (GEO)	35,786 km	24 hours exactly	TV broadcast, weather, communications
Geosynchronous (GSO)	~35,786 km	24 hours	Any 24h period orbit, can be inclined
Highly Elliptical (HEO)	Varies	12–24 hours	Molniya comms orbits over high latitudes
Graveyard orbit	~36,000 km	Slightly over 24h	Retired GEO satellites

How to Use the Calculator

1. Enter orbital altitude in km
2. Get orbital velocity (km/s), period (minutes/hours), and orbits per day
3. Or enter desired period to get required altitude

The CalcHub calculator also shows the ground track speed — how fast the satellite's shadow moves across Earth's surface.

Key Orbital Parameters

International Space Station: ~408 km altitude, 92.9 min period, 7.66 km/s orbital velocity, ~15.5 orbits per day. The ISS travels the equivalent of the distance to the Moon and back in roughly 1.3 days. GPS Satellites: ~20,200 km altitude, 11.97 hours period, 3.87 km/s. Two orbits per day with precise timing that enables GPS accuracy. Geostationary Belt: Exactly 35,786 km above the equator, 3.07 km/s orbital velocity. From the ground, a geostationary satellite appears completely stationary — enabling continuous coverage for communications and weather observation.

Why Satellites Don't Fall

A satellite isn't defying gravity — it's falling constantly, but moving fast enough sideways that it curves around Earth rather than hitting it. At 7.66 km/s in LEO, in the time it takes to fall 5 meters downward due to gravity, the Earth's surface has curved away by 5 meters. This balance is maintained precisely by the orbital mechanics.

How much does atmospheric drag affect LEO satellites?

Even at 400km altitude, there's a very thin atmosphere that creates drag, slowly lowering the orbit. The ISS loses several km of altitude per month and requires periodic reboosts from docked spacecraft. SpaceX's Starlink satellites at 550km experience less drag but still need occasional orbital maintenance. Below ~200km altitude, satellites decay and re-enter within days.

What happens to dead satellites?

Without active propulsion, satellites in LEO gradually decay into the upper atmosphere and burn up within years to decades depending on altitude. Satellites in GEO never naturally decay on human timescales, which is why operational satellites at end of life are moved to a "graveyard orbit" slightly above GEO to clear the valuable operational slot.

Can I see satellites with the naked eye?

The ISS and large Starlink satellite trains are easily visible at magnitude -3 to -4 during passes — brighter than most stars. Regular satellites at 400–600km are visible at magnitudes 2–5 during twilight hours when they're still illuminated by the Sun while your ground location is in darkness. The Heavens-Above.com website provides pass predictions for your location.

Related Calculators

• Orbital Period Calculator — Kepler's laws for planetary orbits
• Planet Weight Calculator — gravity at different altitudes
• Light Year Converter — distances beyond Earth orbit