Why does GPS distance keep increasing while you're standing still?

The short answer

A GPS fix is never perfectly exact. Even standing on one spot, each new position your phone reports lands a metre or two, sometimes more, from the last one, because the calculation behind it is remade from scratch on every update rather than remembered. A track is built by adding up the straight-line distance between consecutive points, and it has no way to tell 'stayed still but the fix wandered' apart from 'walked a metre'. Wander a little in a dozen different directions over a few minutes and those small, meaningless hops add up to real, countable distance, even though you never took a step.

This is normal GPS jitter, not a fault in the recording. It is also usually small relative to a whole hike — a few extra metres from a five-minute stop rarely changes the total you care about.

Why a phone that isn't moving still reports a moving position

A GPS position comes from timing signals arriving from several satellites at once and triangulating a location from the differences. That calculation depends on which satellites are currently visible, how strong each signal is, and whether it reached the receiver directly or bounced off something first — a phenomenon called multipath, common near rock faces, tree cover or buildings. None of those conditions hold perfectly still even when you do: satellites move across the sky, a signal that was clean a moment ago can pick up a reflection off a nearby boulder, and the receiver reprocesses the whole thing fresh each time. The result is a small cloud of slightly different answers to the same question, "where am I right now," rather than one fixed answer repeated exactly.

Open sky produces a tighter cloud than a narrow gully or a spot under trees, which is why the same ten-minute stop can add a barely-noticeable amount of distance at an open summit and a more noticeable amount at a shaded viewpoint with poor sky visibility.

How much distance this actually adds

There is no fixed number, because it depends on how noisy the signal is at that particular spot and for how long you stay put. As a rough sense of scale: a fix that is jittering by a few metres, logged every second or two for several minutes, can add up to a few tens of metres of phantom distance by the time you move on — enough to notice if you are watching the number in real time, rarely enough to change a multi-kilometre total in any way that matters.

It stops mattering to the final figure for the same reason a single spike does — a long hike is made of thousands of points, and a short stretch of jitter is a small fraction of the whole. Where it is worth noticing is a short route, or a route with several long stops on it, where the padded stretches make up a larger share of the total.

Why some apps handle this better than others

Recording apps that care about this filter for it, in one of two ways. Some watch your GPS speed and treat anything below a small threshold as stationary, holding off on adding distance while you are effectively still. Others rely on you actively pausing the recording at a stop, which removes the guesswork entirely — nothing is being logged, so there is nothing for jitter to pad.

A speed threshold is a compromise rather than a perfect fix: set it too low and a noisy fix at a genuine standstill can still slip past it; set it too high and real, slow movement over rough ground gets misread as no movement at all. That is why a deliberate pause, where you tell the app you have stopped rather than letting it guess from the GPS signal alone, tends to produce the cleanest number.

What to do with the number

A small, gradual creep in distance during a stop is not something to chase down or worry about — it is the expected cost of measuring position with radio signals rather than a measuring wheel. Treat the final distance on a normal-length hike as accurate to within a small margin rather than to the metre, and it will match your experience of the day far better than trying to explain every last few tens of metres.

If instead you see one large, sudden jump while stationary — hundreds of metres in a single update rather than a slow creep — that is a different problem, closer to the single bad fix behind a visible spike on the map, and worth a look rather than a shrug.

TrailCam lets you pause a route and resume it later, and time spent paused is kept out of your moving time, which is the more direct way to stop a long stop from padding a track in the first place.