Fix GPX elevation
A barometric altimeter that hiccuped in the rain or a cold start can spike your elevation profile and inflate total ascent. Smooth it with a rolling average and get a believable climb figure back — without touching where or when you went.
Open the tool
Opens the GPX editor with the fix gpx elevation tool selected. Your file stays on your device — nothing is uploaded.
Open the GPX elevation smootherHow to fix gpx elevation
- Open your file. Drop the recording with the jagged elevation into the editor.
- Pick a smoothing window. Set the window (3–15 points) — wider flattens more; the elevation chart updates so you can judge it.
- Apply & download. Click Apply smoothing and export the corrected GPX. Undo restores the raw profile instantly.
Formats & what's kept
- Input: GPX, FIT, TCX, KML, KMZ
- Output: GPX 1.1
- Preserved: Latitude, longitude, timestamps and every sensor value (HR/cadence/power/temperature) are left exactly as recorded — only the elevation numbers change.
- Changed or dropped: Nothing is deleted. Smoothing averages each point's elevation with its neighbours, so sharp barometric spikes are reduced. It doesn't invent elevation for points that never had any.
A real example
A wet trail run reports 812 m of climb because the barometer spiked in a downpour. A window-5 smoothing brings it to a realistic 540 m that matches the map's contour lines, while the route and pace stay identical.
| Before | After |
|---|---|
| elevation gain 812 m (spiky) | elevation gain 540 m (smoothed) |
Try it yourself with a free sample GPX file — the numbers above are illustrative of a typical case.
Privacy
This edit runs entirely in your browser using the W3C File API — your file is never uploaded, and your original is left untouched (the editor works on a copy). This tool makes no network requests at all to do its job; only route planning and snapping, which this tool doesn't perform, would ever send coordinates to a routing provider.
Frequently asked questions
Does smoothing move my route on the map?
No. Only the elevation value at each point changes; latitude and longitude are untouched, so the line on the map is exactly the same.
How do I choose the window size?
Start at 5. If spikes remain, widen it; if ridges and dips you want to keep start flattening, narrow it. The elevation chart previews each choice before you apply.
Can it add elevation to a flat, all-zero track?
No — smoothing averages existing values and won't fabricate terrain. If your file has no real elevation, it needs an external elevation source, which this privacy-first tool deliberately doesn't call.
Will it change my heart rate or power?
No. Only elevation is smoothed; HR, cadence, power and temperature stay exactly as recorded, and timing-based metrics like speed are unaffected.