Satellite Coverage Area Calculator
The satellite coverage area (or ground footprint) is the area of Earth's surface visible from a satellite above a minimum elevation angle. This calculator uses spherical Earth geometry to compute the Earth central angle, ground footprint radius, and coverage area as a spherical cap. Enter the satellite's orbital altitude above the Earth's surface and the minimum elevation angle for your ground stations. Earth's mean radius is 6,371 km per the International Earth Rotation and Reference Systems Service (IERS).
Satellite coverage area formulas
Re = 6,371 km (Earth mean radius)
el_rad = elevation_angle x pi / 180
rho = arccos(Re / (Re + h) x cos(el_rad)) - el_rad (Earth central angle)
Footprint radius = Re x rho (km, for rho in radians)
Coverage area = 2 x pi x Re^2 x (1 - cos(rho)) (km2)
Earth fraction = Coverage area / (4 x pi x Re^2)
Earth mean radius Re = 6,371 km is the IERS standard value. The Earth central angle rho is computed from the spherical triangle formed by the satellite, Earth center, and the coverage-edge point. The coverage area formula for a spherical cap uses the haversine-related expression 2 x pi x Re^2 x (1 - cos(rho)).
Satellite orbit types and coverage
- Low Earth Orbit (LEO, 160-2,000 km): small footprint; needs large constellation for global coverage. Example: Starlink at 550 km.
- Medium Earth Orbit (MEO, 2,000-35,786 km): GPS satellites at 20,200 km cover large areas.
- Geostationary Earth Orbit (GEO, 35,786 km): approximately 42% of Earth's surface from one satellite; zero relative motion means fixed dish antennas. High latency (approximately 240 ms round trip).
- Highly Elliptical Orbit (HEO): Molniya orbits provide extended coverage over high latitudes.
Satellite coverage area calculator: frequently asked questions
What is a satellite's coverage area?
A satellite's coverage area (or footprint) is the area on the Earth's surface from which the satellite is visible above a given minimum elevation angle. At higher orbital altitudes, the footprint is larger. At lower minimum elevation angles, the footprint extends to lower elevations but signal quality degrades and multipath interference increases.
What is the minimum elevation angle?
The minimum elevation angle is the lowest angle above the horizon at which a ground station can receive a usable signal from the satellite. Typical values are 5-10 degrees for data services and 15-20 degrees for voice or precision positioning. Lower elevation angles mean the signal travels through more atmosphere, increasing path loss and atmospheric delay.
How does orbital altitude affect coverage?
Higher orbit means a larger footprint. A satellite at geostationary orbit (35,786 km) can see approximately 42% of Earth's surface. A satellite at 1,000 km LEO has a much smaller footprint, requiring a constellation of dozens to hundreds of satellites for continuous global coverage. GEO satellites are ideal for fixed broadcast services; LEO is better for low-latency communications.
How is the Earth central angle calculated?
The Earth central angle (rho) = arccos(Re/(Re+h) x cos(el)) - el, where Re is Earth's mean radius (6,371 km), h is orbital altitude, and el is the minimum elevation angle in radians. This is derived from spherical triangle geometry relating the satellite, Earth's center, and the ground station at the coverage edge.
What is the coverage area formula?
Coverage area = 2 x pi x Re^2 x (1 - cos(rho)), where rho is the Earth central angle and Re is Earth's radius. This is the formula for a spherical cap area. The result is in km2 when Re is in km. As a fraction of total Earth surface area (510,072,000 km2), it gives the percentage of Earth covered.
Official sources
- NASA: Orbital Mechanics (NASA Small Spacecraft Technology).
- ITU: ITU Radiocommunication Sector - Space Services.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.