GpxFix Blog

Understanding and Fixing Saw-Pattern GPS Tracks

By Roy Lachica on June 25, 2026. Last updated June 25, 2026.

Have you ever looked at a GPS track and noticed it looks jagged, zigzag, or messy when zoomed in, like the teeth of a saw? This phenomenon, often called a "saw-pattern," "saw-tooth," or "zig-zag" track, is a common GPS accuracy issue where trackpoints bounce back and forth along your actual path of travel. This not only looks messy but also inflates the distance of your activity—sometimes doubling your recorded distance on your Garmin, Apple Watch, or other fitness tracker. This guide explains why GPS tracks go wrong and how you can fix inaccurate GPS data.

Example of a saw-pattern GPS track

What Does a Saw-Pattern Track Look Like?

Instead of a smooth line following a road or trail, a saw-pattern track shows a series of sharp, back-and-forth movements—a zigzag GPS error. If you were running or cycling in a straight line, the GPS track might show you repeatedly jumping a few meters back and then forth again throughout the recording. This GPS drift results in a significantly longer track distance, inaccurate pace data, and an unrealistic representation of your route on Strava, Garmin Connect, or other fitness apps.

How to Detect Saw-Pattern Tracks

Visual Inspection: The easiest way is to zoom in on your track on a map (Strava, Garmin Connect, etc.). The jagged, saw-tooth zigzag pattern is usually obvious when you inspect your GPS route closely.
Unrealistic Speed/Pace: Your speed graph will likely show erratic spikes and inconsistent pace. The constant back-and-forth movement tricks the software into thinking you're moving much faster than you are, resulting in wrong pace calculations.
Inflated Distance: If your recorded distance seems unusually high for the run, ride, or hike you did, a saw-pattern GPS error is a likely culprit. You might see distances that are 20-50% too long.
Auto warning: GpxFix may auto detect and show a warning when this GPS accuracy problem happens.

What Causes Saw-Pattern Tracks?

This GPS accuracy issue is almost always caused by errors in how your GPS device (watch, bike computer, or phone) receives and processes satellite signals.

Inherent GPS signal noise: This is the primary culprit for inaccurate GPS tracks. Every position fix has random error baked in due to tiny timing uncertainties in the satellite signals. This noise is always present; it only shows up as a zigzag when your movement is small relative to that noise.
Multipath interference: GPS signals bounce off buildings, trees, cliff faces, or even the ground before reaching your receiver. The device receives both the direct signal and delayed reflections simultaneously, which distorts the position calculation in ways that can oscillate back and forth—a major cause of GPS errors.
Satellite geometry (PDOP): GPS accuracy degrades when the visible satellites are clustered together in the sky rather than spread out. This can cause temporary bursts of larger positional error and poor GPS reception.
Atmospheric delays: The ionosphere and troposphere slow GPS signals down unpredictably, adding variable error that contributes to GPS drift.
Device/antenna movement: If the GPS watch is in a chest pocket or bouncing on your body during running or cycling, the antenna's orientation to the sky changes rhythmically. This can introduce a periodic error pattern that mimics a back-and-forth motion.
Low update rate: If the device only records a GPS point every 5–10 seconds (common in battery-saving modes), you've moved 15–30 meters between fixes — but the noise per fix stays the same. The zigzag looks worse because the gaps between points are large enough to make the lateral scatter very visible relative to the path.

Why it looks like back-and-forth specifically (not just scatter)

Random GPS noise tends to mean one fix is ahead of true position, the next is behind — because the error has nowhere else to go along a narrow corridor like a road or trail. The constraint of the path you're on (running route, bike path, hiking trail) turns what would otherwise be 2D scatter into an apparent 1D oscillation along the direction of travel, creating that characteristic zigzag GPS pattern.

How to Fix Saw-Pattern Tracks with GpxFix

Fortunately, you don't have to live with messy GPS data. GpxFix provides tools to clean up these GPS errors and fix inaccurate tracks from your Garmin, Apple Watch, Wahoo, or other GPS devices.

Our advanced GPS smoothing algorithm is specifically designed to detect and correct saw-pattern tracks and zigzag GPS issues. When you upload your GPX file or TCX file, GpxFix can analyze the track for characteristics of multipath errors, such as unrealistic changes in direction and speed.

Upload your GPX file, TCX file, or FIT file to GpxFix.
Use our "Fix GPS issues" feature to correct GPS errors.
The tool intelligently averages the erratic points, creating a new, much smoother track that more accurately follows your real path—perfect for fixing GPS drift and distance errors.
The corrected file will have a more realistic distance and a clean appearance on the map when you upload to Strava or other fitness platforms.

How to Prevent Saw-Pattern Tracks in the first place

While you can fix a bad GPS track, it's even better to prevent GPS accuracy problems before they happen.

Wait for a Strong GPS Lock: Before you press start on your activity, give your device a minute or two to acquire a strong signal from multiple satellites. Most GPS watches will show a "GPS Ready" or similar message with green signal bars.
Use Multi-Band/Dual-Frequency GPS: If you're serious about GPS accuracy for running, cycling, or hiking, your next device should have this feature. Modern Garmin, Apple Watch Ultra, and other premium fitness trackers with dual-frequency GPS are game-changers for reducing multipath errors.
Be Aware of Your Surroundings: Know that your GPS track is more likely to have accuracy problems in deep canyons, dense forests, urban areas with tall buildings, and under tree cover.
Keep a Clear View of the Sky: If possible, wear your GPS watch on your wrist or keep your device in a location with an unobstructed view of the sky (e.g., not at the bottom of a backpack or in a pocket).
Disable Auto-Pause for Slow Activities: For hiking or trail running where you stop frequently, "auto-pause" can sometimes cause GPS tracking issues when it resumes. Consider using the manual lap button or just letting it run continuously.

Conclusion

A saw-pattern GPS track is a frustrating but solvable problem. It's caused by the inherent challenges of receiving faint satellite signals in difficult environments, leading to zigzag GPS errors and inaccurate distance tracking. By understanding the causes of GPS drift and accuracy issues, you can take steps to get a better recording on your Garmin, Apple Watch, or other fitness tracker. And for those times when the environment wins, GpxFix is here to help you fix GPS errors, clean up the data, and get an accurate track you can be proud of—whether you're running, cycling, or hiking.