Method
How GPX Adjuster applies corrections.
GPX Adjuster works from the file you recorded. It rescales route or timing data based on the values you enter and shows the result on a map before you download the updated GPX.
Distance
Distance changes are applied by scaling the recorded route shape.
The recorded route is treated as a shape. GPX Adjuster finds the route centroid and scales every point outward or inward by one factor so the total measured distance moves toward the official event distance.
Small corrections usually remain close to the original route. Larger changes can distort the shape, so the map preview should be used to confirm that the result still matches the activity you recorded.
Time
Timestamps are rescaled without rewriting the route geometry.
Time correction preserves point order and rescales timestamp offsets from the start so total duration matches the official result you enter.
That is useful for a slightly late watch start, an early stop, or other small recording misses. It does not fabricate a different route.
Cadence
Samsung Health cadence issues can be corrected automatically.
If the file metadata indicates Samsung Health, GPX Adjuster can automatically apply the cadence correction that Strava often needs.
The adjusted file is still shown in the same before-and-after preview so you can review the result before downloading it.
Review
Use the preview to confirm that the adjusted file still looks correct.
Good use cases are things like a 9.99 km recording for a 10 km race, a minor timing mismatch, or a cadence export issue. The tool is best suited to small corrections that can be checked against the route preview.
The map preview is there for a reason: if the adjusted route no longer looks like the race you ran, do not use it.