GpxFix Blog

Manually Fixing a Track That Drifted Far Off Course

By Roy Lachica on October 13, 2026. Last updated October 13, 2026.

Most GPS problems can be cleaned up automatically with GpxFix. Spikes get removed, missing sections get filled from a reference file, and small amounts of drift get smoothed back onto the road. But every so often a recording is so badly broken that no automatic tool can rescue it, the GPS drifted hundreds of meters off the actual path for a long stretch, and there is nothing clean nearby to anchor a correction to. When that happens the fastest reliable fix is to do it by hand: delete almost all of the bad points, keep a handful of anchor points, and drag those anchors back onto the real route. This post explains exactly how to do that and when it is the right approach.

Why some tracks cannot be fixed automatically

Automatic repair relies on there being some signal of where you actually went. A spike filter assumes the points on either side of the spike are correct. A reference-file repair assumes you have a second clean recording of the same route. Smoothing assumes the drift is small enough that pulling points toward their neighbors still lands on the real path. When the GPS wanders a long way off course for minutes at a time, none of those assumptions hold, the "correct" neighbors are themselves wrong, and the algorithm has no way to know where the real route was. In those cases you, the person who was actually there, are the only reliable source of truth.

The idea in one sentence

Keep just enough points to describe the shape of your real route, delete everything that drifted, and move the points you kept onto the path you actually travelled. GpxFix redraws the line between your anchor points and recalculates distance from the corrected positions. The reason you want to delete most of the track points is that it will typically be hundreds or even thousands of track points, and dragging each one back onto the real path would be really tedious and error-prone. A few well-placed anchors are all you need to rebuild the section.

Step by step

1. Open your file in the map editor. Upload the GPX, FIT, or TCX file and open it on the interactive map so you can see every track point plotted against the real streets and trails underneath.
2. Identify the drifted stretch. Scroll along the track until you find where it leaves the real route, wanders off, and eventually returns. Note the last good point before the drift and the first good point after it, these are the boundaries of the section you will rebuild.
3. Keep a few anchor points, delete the rest. Inside the drifted stretch you do not need every point, you only need enough to capture the shape of the route: one at each corner, one at each significant bend, and one on any long straight. Delete all the other drifted points by clicking on or near them using the right mouse button. On a straight road two anchors (start and end) may be enough; a twisty trail might need one every turn.
4. Drag each remaining anchor onto the real path. Pick up each kept point and drop it exactly on the road, trail, or track you actually travelled, using the map underneath as your guide. Work in order along the route so the line stays untangled.
5. Check the redrawn line. As you move the anchors, GpxFix connects them in sequence. Make sure the line now follows your true route and does not cut a corner or cross a building. Add an extra anchor point anywhere the straight line between two anchors deviates from the real path.
6. Review distance and speed. Because the corrected points sit on the real route, the total distance will drop from the inflated drifted value to something realistic. Confirm the new distance looks right before you finish.
7. Download the corrected file. Save the cleaned track and upload it back to Strava, Garmin, or wherever you keep your activities.

How many points should I keep?

Fewer than you think. A track point every second looks detailed, but for a corrected section the shape is what matters, not the density. Keep a point wherever the direction of travel changes and skip the ones in between. A long straight only needs its two endpoints. A hairpin needs one at the apex. Over-keeping points just means more of them to drag, and each one you keep is another point that was in the wrong place and now has to be placed by hand.

Scenarios where manual fixing may be the right tool

• Deep urban canyons. Running between tall buildings, the signal bounces off glass and the track jumps a block or two off the real street for a while. There is no reference file and the drift is too large to smooth, so you reroute the section by hand along the street you actually ran.
• Dense forest or deep valleys. Under heavy tree cover or in a steep ravine the track can wander far from the trail. If you know the trail you took, a few anchors dragged onto it rebuild the section cleanly.
• A watch that locked onto the wrong position. Occasionally a device fixes onto a bad position at the start and drags a long rubber-band line across the map before it recovers. Delete the stray points and anchor the real start.
• No reference file exists. The automatic reference repair is great, but only if you have a clean recording of the same route. For a one-off route nobody else recorded, manual correction is the only option.
• Indoor-to-outdoor transitions. Starting inside a building or car park, the first minutes drift wildly until the signal settles. Trim and reposition those early points onto your true starting path.
• Reflections off water or metal. Along a waterfront, marina, or large metal structure the signal can mirror and place you offshore. Reanchor the few kept points back onto the shoreline path.

When to try something else first

• If the drift is small, within a few tens of meters, try the automatic smoothing first, it is faster and keeps all your original detail.
• If you have a clean recording of the same route, use the reference-file repair instead, it rebuilds the section automatically from real data.
• If the problem is isolated spikes rather than sustained drift, the spike remover handles those without any manual work.

A note on honesty

Manual correction is about restoring where you actually went, not inventing a route you did not travel. Drag the points onto the real path you remember taking, keep the distance realistic, and do not reshape a section to look faster or longer than it was. Used this way, hand-editing simply undoes a GPS error that the device made on your behalf.

Frequently asked questions

Will deleting points change my time?

Each kept point keeps its own timestamp, so the overall elapsed time of the activity stays the same. You are changing where the points sit on the map, not when they were recorded.

Can I add points back if I delete too many?

Yes. If a straight line between two anchors cuts a corner, add a new point on the real path between them and drag it into place. You can keep adding anchors until the line matches your route.

How do I know the new distance is correct?

Once the anchors sit on the real route, GpxFix recalculates distance from their positions. Compare it against a route you know, or measure the same path on a map, to confirm it is sensible.

Got a track that drifted too far for the automatic tools? Open it in GpxFix and reroute the bad section by hand. Related reading: why some GPS activities cannot be fixed and repairing a workout using a reference GPX file.