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How many satellites needed for GPS

The Magic Numbers of GPS Satellites

To operate a Global Positioning System (GPS), a minimum of 24 satellites is generally required: here’s why:

These satellites are strategically positioned in six Earth-centered orbital planes, each with four satellites. This configuration ensures that at least four satellites are available from any point on Earth at any given time, which is necessary for accurately determining a position.

Each GPS satellite transmits signals that allow GPS receivers to calculate their precise location (latitude, longitude, and altitude) as well as the exact time. The system is designed to be redundant, meaning that even if one or more satellites fail or are obstructed, other satellites can still provide sufficient coverage for accurate

For an accurate GPS location, a minimum of four satellites is required. Here’s why:

For an accurate GPS location, a minimum of four satellites is required. Here’s why:

  1. Latitude and Longitude: The first two satellites provide information that helps in determining a position in terms of latitude and longitude.
  2. Altitude: A third satellite adds the ability to calculate altitude, making it possible to determine a three-dimensional position.
  3. Time Offset and Improved Accuracy: The fourth satellite is used to correct any time discrepancies between the clock in the GPS receiver and the atomic clocks on the satellites. This correction is crucial for precision because the system relies on extremely accurate timing. The fourth satellite also improves overall positional accuracy.

With just three satellites, it’s possible to get a rough estimate of location, but it may not be highly accurate. Four or more satellites ensure better accuracy, and the more satellites a GPS receiver can ‘see’, the more accurate the location data will be. Modern GPS systems often use signals from more than four satellites to provide enhanced accuracy and reliability.

Learn how trilateration with three satellites theoretically suffices for determining position, but the fourth satellite is essential for correcting timing errors caused by less accurate GPS receiver clocks
Calculating the location of your mobile device ( the blue dot )
About the Author
I'm Daniel O'Donohue, the voice and creator behind The MapScaping Podcast ( A podcast for the geospatial community ). With a professional background as a geospatial specialist, I've spent years harnessing the power of spatial to unravel the complexities of our world, one layer at a time.