SummitGPX Help Centre

GPX Simplification Explained

GPX simplification reduces the number of points in a route while keeping the shape of the line as accurate as possible.

This is useful when a GPX file is very large or struggles to import on GPS watches and navigation apps.

Why GPX files get large

A GPX track can contain thousands of points.

<trkpt lat="50.1001" lon="-5.1001" />
<trkpt lat="50.1002" lon="-5.1002" />
<trkpt lat="50.1003" lon="-5.1003" />
<trkpt lat="50.1004" lon="-5.1004" />

A long ultra marathon route may contain a very large number of points, especially if it was recorded from a GPS device.

Why large GPX files can be a problem

Large files can:

  • Be slow to download
  • Fail to import on some watches
  • Perform badly in mapping tools
  • Make route management harder
  • Increase storage and processing time

What simplification does

Simplification removes unnecessary points while keeping the route shape.

A dense section like this:

Point 1
Point 2
Point 3
Point 4
Point 5

May be reduced to:

Point 1
Point 3
Point 5

If the removed points do not meaningfully change the line, the route still looks the same.

The balance

Too little simplification and the file stays large.

Too much simplification and the route line may cut corners or lose detail.

For race routes, accuracy matters. Simplification should be careful, especially on technical terrain, switchbacks, coast paths, mountain paths and woodland trails.

How this relates to SummitGPX

SummitGPX preserves the route geometry from the uploaded GPX file. It does not aggressively simplify the route line during upload, because race route accuracy matters.

The Free GPX Health Check can help identify files that are too large, too sparse or likely to cause watch compatibility problems. If you need a simpler file for a device, create a carefully simplified copy in your route planning tool and check it before sharing.