Compress a GPX file: make it smaller by removing points the route's shape does not need, and see what that does to its distance and climb. Everything runs in your browser — nothing is uploaded.
Does your watch or app refuse files with too many points? Choose and enter its number.
GPS watches and phones often record a point every second, so a day out becomes tens of thousands of coordinates. Some watches, apps and route planners limit how many points a course may have, and large files are slow to upload, render and share. Most of those points add nothing to the shape of the route.
We measured twelve real routes, seven of them recorded on a watch or phone, from a 10 km mountain race to the 126 km Transgrancanaria and the Kungsleden in Arctic Sweden. At the recommended 10 m they kept 5–44% of their points: distance read up to 4.4% shorter, mostly recording zigzag straightened out, and climb stayed within 3%. At 50 m they kept 2–19% of their points and read up to 13% shorter, and climb still stayed within 1.5%. The table above shows the same figures for your own file, so you can pick the level that suits it.
Removing points can cut the top off a climb. Judged by shape alone, the recorded routes lost up to 10.5% of their climb at 10 m and 19% at 50 m. So the Simplifier also keeps any point the simplified line would otherwise pass more than 5 m above or below. Rises and falls of 5 m or less, which a GPS records as noise, are left out of that test, the same threshold the climb figures use, so they cost no points.
Some watches, apps and sites accept only so many points in a course. Choose Point limit and the Simplifier keeps the points that matter most for that number: the sharpest bends, and the tops and bottoms of climbs, which count three times as much as a bend of the same size. On the twelve routes, 1,000 points kept climb within 3.1% and distance within 5.4%, and 2,000 points kept both within 2.2%; judged by shape alone, 1,000 points lost up to 10.7% of the climb. If the number is too small for a long route, the page says so beside the result. Limits differ by device and app, so check yours; we do not list them.
Under the result, Split into parts cuts the file at its segments (one file per day of a multi-day recording), at stops you choose (an aid station, an overnight pause), or into equal lengths. Each part is simplified with the same setting, so with a number of points each part holds at most that many, and each begins exactly where the one before it ends: loaded one after another, the parts make the whole route. Waypoints go with the part they lie on, and one at a cut goes with both. When a number is too few for the whole route, the page works out how many equal parts would keep every part within 5% of its distance and climb.
Whatever you choose, the start and end of every segment are kept, and so are stops: the track point nearest each waypoint on the route (an aid station, a hut, a water source) and the points either side of a pause of ten minutes or more in a recording. A number smaller than those need is refused with the smallest number that works; the Simplifier never meets a limit by cutting the end off your route.
The tool uses the Ramer–Douglas–Peucker algorithm. For each stretch it finds the point furthest from the straight line between the stretch's ends; if that point is further than the tolerance, it is kept and both halves are checked the same way, otherwise the points in between are removed. Distances are measured in metres on the ground at your route's latitude. Each track segment is simplified on its own, so a file with several days or a pause between recordings keeps them apart, and both ends of every segment are always kept.
Simplifying removes only track or route points. Waypoints, names, timestamps, heart-rate and other extensions on the points that remain, and the file's metadata, are kept as they were, unless you choose in Clean to remove the timestamps or the sensor data. Cleaning also drops points that repeat the one before them and points whose coordinates cannot be read, and says how many. The climb figures use the same 5 m threshold as the TrailSplits Course Analyzer, Elevation Profile and Route Packet, so all four agree.
Your GPX file stays in your browser. Nothing is uploaded.