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How does GPS work?

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Quick answer

GPS works by using a network of satellites that constantly broadcast their position and the time. Your device receives signals from several satellites and calculates its exact location from how long each signal took to arrive. Around 30 satellites orbit Earth, each broadcasting its position and a precise time.

Step by step

  1. Around 30 satellites orbit Earth, each broadcasting its position and a precise time.
  2. Your receiver measures the tiny delay of signals from at least four satellites.
  3. From those delays it triangulates latitude, longitude, and altitude.
  4. Atomic clocks on the satellites make the timing precise.

People also ask

How many satellites does GPS need?
At least four to pin down your 3D position (latitude, longitude, and altitude).
Does GPS need the internet?
No — GPS itself works from satellite signals; the internet only helps load maps and speed up the first fix.
Why is GPS sometimes inaccurate?
Tall buildings, tree cover, and atmospheric effects can delay or block satellite signals.