How GPS Coordinates Work
An intuitive explanation of the Global Positioning System, satellites, trilateration, and modern geolocation.
The Global Positioning System (GPS) is a network of over 30 satellites orbiting the Earth at an altitude of approximately 20,000 kilometers (12,550 miles). Each satellite continuously broadcasts a radio signal containing its exact orbital position and an atomic clock timestamp.
The Principle of Trilateration
A GPS receiver in your smartphone or car navigation system does not transmit any signals back to space. Instead, it passively listens to satellite broadcasts:
- Measuring Time of Flight: By comparing the time a signal was sent with the time it was received, your device calculates its precise distance to each satellite ().
- Intersection of Spheres:
- A signal from one satellite places you anywhere on a giant sphere.
- Signals from two satellites narrow your location to the circle where two spheres intersect.
- Signals from three satellites pinpoint two possible points in space (one of which is typically in outer space).
- Signals from four or more satellites resolve your exact 3D coordinates (latitude, longitude, altitude) and correct the receiver’s internal clock error.
Coordinate Reference Systems (WGS 84)
Most consumer mapping and GPS tools operate on the WGS 84 (World Geodetic System 1984) standard. This mathematical ellipsoid model accounts for the fact that the Earth is slightly flattened at the poles and bulges at the Equator.
Check your current coordinates or test any global location using our Latitude Longitude Finder.
