Why GPS Tracks Cut Corners on Curved Roads and Trails
Learn why sparse samples connect with straight lines and how this affects route maps and total distance.
A GPS track is a sequence of sampled positions, not a continuous recording of every movement. When a road curves between two samples, a straight line connecting those points cuts across the inside of the bend. This can make the recorded distance shorter than the path actually travelled.
Sampling geometry
The farther apart two samples are, the more likely a straight segment is to miss intermediate turns. The effect is noticeable on switchbacks, roundabouts and winding paths. More frequent sampling can capture the shape better, but it also creates more points that may contain position noise.
Why the total can be high or low
Corner cutting tends to under-represent a curved path, while coordinate jitter can add false distance. Both can happen in the same session. The final total reflects the combined effects of sampling, filtering, route shape and receiver uncertainty, so there is no single correction factor that works for every route.
What users can inspect
If a route map is available, look for straight lines across bends, gaps in tunnels or points wandering away from the path. If the site only displays a total, remember that you cannot inspect the underlying geometry. Compare with a mapped route only as a reference, because planned route distance and actual travelled distance may differ.
When precision matters
For official course measurement or survey work, use the designated equipment and procedure. A phone's browser tracker is best treated as an estimate for general awareness. Avoid claiming that a displayed distance is exact merely because the line looks smooth on a map.
Frequently asked questions
Why is my GPS route a straight line through a bend?
The device may not have recorded intermediate points, so the map connects the available samples.
Will faster updates solve it completely?
No. They may preserve more detail, but noisy points and gaps remain possible.
Technical references
These references explain the underlying browser and positioning concepts. They do not imply endorsement of this website.