GPX viewer

How to use it

Drag the GPX onto the tool or pick it with the button. You’ll see the track on the map with its waypoints and, next to it, the distance, elevation gain and loss, highest and lowest points and, if the file has times, the total time, moving time and average speed. If your watch recorded heart rate, cadence or temperature, you get the average too.

Tap a waypoint or a track on the map or in the list to see its data: name, comment, type, elevation and time. The file is read in your browser and isn’t uploaded anywhere.

What a GPX file is

GPX (GPS Exchange Format) is the most common format for GPS routes. It was created by TopoGrafix and is an XML text file; the version in use today, 1.1, dates from 2004. Almost every app and device exports and opens it: Strava, Garmin, Komoot, Suunto, Coros, Gaia GPS or Google Earth.

A GPX file can hold three things. Waypoints (wpt), single named places like a spring or a pass. Routes (rte), a list of points to go through, typical of planning. And tracks (trk), what the GPS actually recorded, split into segments (trkseg) when recording was paused and resumed. Each point can carry its elevation and time, and Garmin’s extensions add heart rate, cadence and temperature.

How distance, elevation gain and time are worked out

Distance is the sum of the legs between each pair of points, measured on the WGS84 ellipsoid with GeographicLib. Elevation gain uses the elevation in the file with the same filter as the GPX elevation profile tool: a climb or a descent only counts once it passes 5 meters (16 ft), so GPS noise doesn’t add up.

Total time runs from the first to the last timestamp in the file. Moving time only adds the legs where you were going faster than 0.4 m/s (0.9 mph) and that last under 10 minutes, so stops don’t count. Average speed is the distance divided by that moving time.

How to get the GPX out of Strava or Garmin

In Strava, open the activity, click the three-dot menu and choose “Export GPX”. In Garmin Connect, open the activity, click the gear icon and choose “Export to GPX”. Most other apps have a “Download” or “Export” button on each route or activity.

If you get a FIT or TCX file instead (the formats watches use internally), export it as GPX from the app. If you have a KML from Google Earth, you can open that here too.

Common GPX problems

The elevation gain doesn’t match Strava. Every app filters elevation its own way, and some correct it with their own terrain model. To compare against the terrain, open the same file in the GPX elevation profile tool, which lets you switch between the GPS elevation and the terrain model.

The track has jumps or spikes. Those are GPS errors, especially right after you start recording, under trees or between tall buildings. They add extra distance.

There’s no time or speed. Planned routes, like the ones you draw in an app before heading out, have no timestamps because nobody has walked them yet. The viewer tells you the file doesn’t have any.

Converting a GPX to KML, GeoJSON or CSV

In KML, tracks with times become gx:Track, Google Earth’s format for timed tracks, with each point’s heart rate and cadence, and waypoints become placemarks with their name, description and type. In GeoJSON, times go in “coordTimes”, the way togeojson writes them, a library many websites use.

The CSV can have one row per track point, with its latitude, longitude, elevation, time, heart rate and cadence, ready for Excel or Google Sheets. If you open the converted file here again, it comes out the same as the original GPX.