What Does GPS Accuracy in Metres Mean?
Learn how to interpret a location accuracy radius and why it is an estimate rather than a guarantee of exact position.
A location response may include an accuracy value in metres. This is not a promise that the true position is exactly that distance away, nor is it a score for the speed reading. It is an estimate of horizontal uncertainty as defined by the location provider and platform.
Read the number with its context
A reported accuracy of 8 metres generally indicates a more constrained horizontal estimate than 80 metres, but the exact statistical interpretation depends on the provider. It does not mean every point inside a circle is equally likely, and it does not describe altitude accuracy. A page should present it as an estimate and avoid claiming survey-grade precision.
Why accuracy changes
The value may improve when the phone has a clear sky view and receives fresh signals, then worsen indoors or between tall buildings. Wi‑Fi, cellular positioning, device settings and operating-system algorithms may contribute. The browser requests a location; it does not control every part of how the system estimates that location.
Accuracy is not speed accuracy
A horizontal position estimate and a speed estimate are related but not interchangeable. Some devices provide a speed value and speed accuracy; many browser interfaces expose position accuracy but not a comparable speed uncertainty. Do not convert a location accuracy radius directly into a claim such as 'speed is accurate within one kilometre per hour.'
A practical decision rule
If the reported accuracy is poor or the value is stale, wait for a better fix or stop using the reading for the current task. A useful display should show uncertainty where available and avoid hiding it behind excessive decimal places. More digits are not the same as more information.
Frequently asked questions
Does 5 m accuracy mean the speed is accurate to 5 m?
No. It describes horizontal location uncertainty, not speed uncertainty.
Is lower accuracy number better?
Generally, a smaller reported horizontal accuracy radius indicates a more precise estimate, but it is still only an estimate.
Technical references
These references explain the underlying browser and positioning concepts. They do not imply endorsement of this website.