Simplify GPX & Reduce File Size
Cut a huge GPX down to size. A slider controls how aggressively points are removed, and you see the point count and file size shrink live — the route shape stays.
All processing happens in your browser — your files never leave your device.
How to use the Simplify GPX & Reduce File Size
- Drop your oversized .gpx file onto the box above.
- Drag the tolerance slider. Higher tolerance removes more points.
- Watch the live readout: point count and file size before → after, plus the percent reduction.
- Glance at the route thumbnail to confirm the shape still looks right.
- Click Download to save the slimmed-down GPX.
Why GPX files get so big
A device that records a point every second produces tens of thousands of points on a long ride. Most of them sit almost perfectly on a straight line and add nothing but file size. Some apps and websites reject GPX files over a few megabytes, older GPS units choke on high point counts, and email or upload limits get in the way. Simplifying removes the redundant points while keeping the ones that define the route's shape.
The Douglas-Peucker algorithm
TrackKit uses the Ramer-Douglas-Peucker algorithm, the standard method for line simplification. It works recursively: draw a straight line from the first point to the last, find the point that sits furthest from that line, and keep it only if its distance exceeds your tolerance. Then repeat on each half. Points that lie within the tolerance of the simplified line are discarded because they carry no meaningful shape information. The result keeps sharp corners and switchbacks while thinning out long, near-straight stretches.
Choosing a tolerance
Tolerance is measured in metres — the maximum distance a removed point may sit from the retained line. A tolerance of 1–2 m barely changes the track but still strips a surprising number of points. Around 5–10 m gives a big size reduction that looks identical at normal zoom. Go higher only if you need an aggressive cut and can accept visibly straighter corners. Because you can see the shape and the numbers update as you drag, you can dial in exactly the trade-off you want.
What is kept and what is lost
The first and last point of every segment are always kept, so your track never gets shorter at the ends. Elevation, timestamps, heart rate and cadence stay attached to the points that survive. The points that are removed take their per-point data with them, which is expected — you are choosing to store the route more coarsely. Distance may shrink by a hair because a simplified line cuts tiny corners, but at sensible tolerances the change is negligible.
Runs on your machine
Here is something most online converters gloop over: a route file is a map of your life. The start and end of a run is usually your front door. A "morning loop" repeated fifty times is your home address with a timestamp. That is exactly why TrackKit does the whole conversion inside your browser using the File API. The bytes are read into memory, transformed, and handed back as a download. Nothing is uploaded, nothing is logged, and there is no server that could be breached or subpoenaed. You can open the network tab in your browser and watch: not a single request leaves the page after it loads.
Frequently asked questions
Will simplifying ruin the shape of my route?
No, if you use a sensible tolerance. Douglas-Peucker keeps the points that define corners and curves and only removes ones that sit almost on a straight line. The thumbnail lets you confirm the shape before downloading.
What tolerance should I use?
Start at 1–2 m for a safe trim, or 5–10 m for a big size cut that still looks identical at normal zoom. Drag the slider and watch the point count and shape until you are happy.
How much smaller will the file get?
It depends on how densely your device recorded, but 70–95% fewer points is common for one-second GPS tracks. The live readout shows the exact before-and-after point count and file size.
Are the start and end points kept?
Always. The first and last point of every track segment are preserved, so your route never gets clipped at the ends.
Does it keep heart rate, elevation and time?
Yes, on every point that survives simplification. Removed points take their own data with them, which is the point of simplifying.
Is the algorithm the same one mapping libraries use?
Yes. It is Ramer-Douglas-Peucker, the same well-tested line-simplification method used across GIS and mapping tools, implemented to run on tracks with tens of thousands of points without freezing.
TrackKit converts your files as faithfully as each format allows, but formats are not identical and some data cannot survive every conversion (see the notes above each download). Distance and elevation figures are computed from the points in your file and are estimates for general use, not survey-grade measurements. Always keep your original file as a backup.