Why your GPS distance seems off and how to fix it

October 30, 2026 · 6 min read

Most GPS distance errors come from a handful of causes: a weak first fix, tall buildings or thick trees, GPS drift while you stand still, or Precise Location being switched off. Each has a simple fix, and once they’re sorted, phone GPS is usually accurate to within a few percent.

Below, start by matching what you see to the likely cause, then work through the fixes. If you want the background on how it all works, see how your phone measures distance with GPS.

Diagnose it: what does the error look like?

The shape of the problem tells you a lot. Open your route map and compare it to where you actually went.

What you notice	Most likely cause
First few hundred meters are a jagged mess or start in the wrong place	You started before the phone had a good fix
Route zigzags or jumps across streets downtown	Signals bouncing off tall buildings
A spiky star or scribble where you stopped	GPS drift while standing still
Straight lines that cut across parks or buildings	Signal lost for a while (tunnel, underpass, dense cover)
Distance consistently a little short on winding trails	Corners being smoothed between fixes
Route looks blocky or very rough everywhere	Precise Location turned off for the app
Different total from a friend’s phone or another app	Normal: different filtering, different hardware

The six common causes, and how to fix each

Cause 1: Starting before the GPS is ready

When you step out the door, your phone may still be using a rough, Wi-Fi-based position. It takes a few seconds, occasionally longer, to lock onto enough satellites for a precise fix. If you start walking straight away, the first stretch can be wobbly.

Fix: Open your tracking app outside, not in the hallway. Give it 10–30 seconds with a clear view of the sky before you start. Opening a map app and watching the blue dot shrink to a tight circle is a quick way to confirm the phone has a good fix.

Cause 2: Tall buildings, trees and “urban canyons”

In a city center, satellite signals bounce off glass and concrete before reaching your phone. That reflected signal travels farther, so your phone thinks you’re somewhere you’re not. This is called multipath, and it produces the classic zigzag route that crosses the street for no reason. Dense, wet tree cover and deep valleys weaken signals in a similar way.

Fix: You can’t move the buildings, but you can expect it. In very built-up areas, a slightly wider street or a waterfront path often tracks much better than a narrow lane between towers. Over longer walks the zigzags tend to partly cancel out, so a 5 km total is usually more reliable than any single block.

Cause 3: Drift when you stop

Even when you stand still, your reported position wanders by a few meters. Good tracking apps filter most of this out, but a long stop at a café, a playground or a crossing can still leave a small scribble and add a few phantom meters.

Fix: Pause the tracker when you stop for more than a minute or two, and resume when you set off. Using pause also keeps your moving time and average pace honest. If a short stop is all it is, don’t worry; the effect is tiny.

Cause 4: Precise Location is off

iOS lets you give an app only your approximate location. That’s great for a weather app, but a tracker given an approximate location can’t draw an accurate route.

Fix: Go to Settings → Privacy & Security → Location Services, tap your tracking app, and make sure Precise Location is switched on. While you’re there, check that Location Services itself is enabled at the top of that screen.

Cause 5: Signal gaps and corner cutting

When the signal drops, say in an underpass or a long tunnel, the app has nothing to record. When it comes back, it joins the last good point to the new one with a straight line. On a winding path, straight lines between points also shave off a little of every bend.

Fix: There’s not much to do for tunnels, and the effect is usually small. On twisty trails, accept that your total may run slightly short. It’s a consistent bias, so your progress over time is still meaningful.

Cause 6: Where you carry your phone

GPS signals are weak, and your body absorbs some of them. A phone at the bottom of a backpack pressed against your back, or deep in a thick winter coat, gets less signal than one in a jacket pocket or an armband.

Fix: An outer pocket, a hip belt, or an armband generally works better than the bottom of a bag. You don’t need to hold it in your hand, and keeping the screen locked is fine as long as your app supports background tracking.

Quick checklist for better accuracy

1. Turn on Precise Location for your tracking app.
2. Start outdoors and wait a few seconds for a good fix.
3. Keep iOS up to date; location improvements arrive with updates.
4. If tracking has been strange for days, restart your iPhone.
5. Pause during long stops.
6. Carry the phone in an outer pocket or armband rather than deep in a bag.

How to test whether your distance is actually wrong

Feeling that a route is “longer than that” isn’t a reliable test, and neither is comparing against another app, since both could be off in different ways. Use a known distance instead:

• Running track: four laps in the inside lane of a standard 400-meter track is 1,600 meters (just under a mile).
• Marked paths: many parks and riverside paths have distance markers every 100 meters or every quarter mile.
• A planned route: draw the route in a map app and compare, keeping in mind that maps measure the center of the path.

If you’re within about 2–3% on open ground, your tracking is doing its job. For a broader comparison of approaches, see pedometer vs GPS accuracy.

Does a small error even matter?

For most people, not much. If your phone reads 4.9 km on a route that’s really 5.0 km, your fitness hasn’t changed, and your weekly and monthly trends are still accurate because the bias is similar every time. That consistency matters more than perfection, especially when you’re working toward something like a monthly walking goal.

Where it does matter is pace. A short stretch of bad signal can make one kilometer look suspiciously fast or slow. Look at your average over the whole walk rather than any single moment.

FAQ

Why is my GPS distance different from my step count distance?

They measure different things. Step-based distance multiplies your steps by an estimated stride length, which changes with speed and terrain. GPS measures your position on the map. Outdoors, GPS is usually the closer of the two. We compare them in steps vs distance.

Does Low Power Mode make GPS less accurate?

Low Power Mode mainly reduces background activity like mail fetch and some visual effects. Location tracking in an active workout app generally keeps working, so if accuracy drops, check the other causes above first.

Should I recalibrate my iPhone’s GPS?

There’s no manual GPS calibration on iPhone. Making sure Location Services and Precise Location are on, keeping iOS updated and restarting the phone covers almost everything you can do.