Garmin FIT Course (Flexible and Interoperable Data Transfer)
Open BetaFIT is Garmin's binary fitness protocol that powers Forerunner watches, Edge bike computers, Fenix multisport devices, plus Wahoo, Polar and Bryton gear. On osm2cdr we write FIT in the Course profile: the roads and paths of your selected area are chained by nearest endpoints into connected runs — segments follow the ways that touch instead of the order they were read in, and the chaining works at any density, with no cut-off. To be honest about the content: this is the road network of your bbox, not one planned route — where two ways do not meet, the track moves to the next run in a straight line. Those transfers are not counted as distance: lap.total_distance is the length of the ways themselves, not the sum of the jumps between them. Every point carries coordinates (in semicircles, Garmin's integer units), cumulative distance and a timestamp derived from a nominal speed; the file holds a header, file_id, course and lap messages, start/stop events and CRC-16 checksums — fields laid out strictly per the FIT profile and verified with an independent parser. Honest about the data too: this is an export of geometry, not a recorded workout — there is no heart rate, cadence, power or elevation in the file, because those come from sensors during the ride, not from the map. Very long exports are downsampled to 10,000 points — thinning happens inside the runs, and both ends of every run are kept.
Key Features
About FIT Format
FIT is the binary ANT and Garmin protocol that sports devices use to store and transfer data. It is more compact than text formats and is understood far beyond Garmin: FIT is read by Wahoo, Bryton and Polar, as well as by the Garmin Connect, Strava and TrainingPeaks services.
The protocol has several profiles, and two of them are easy to confuse. Activity is a workout that has already happened, with sensor readings. Course is a route the device is supposed to guide you along. Only the second can be made from a map, so a Course is what we write.
The file contains route vertices with coordinates and timestamps, packed by FIT's rules: a header, definition and data messages, and a checksum. Coordinates are stored in Garmin semicircles — as integers rather than fractional degrees. The course is assembled from the roads and paths of the area you selected, not from one planned route: segments are chained by nearest endpoints into connected runs, but where two ways do not meet, the track moves to the next run in a straight line. Those transfers are not counted in the lap distance — it shows the length of the roads themselves, not the sum of the jumps between them. Long exports are thinned down to 10,000 points evenly inside each run, with both ends of every run kept.
There is no heart rate, cadence, power or barometric altitude in the file, and there cannot be: those values are captured by sensors while you move, not by a map.
What Program Opens FIT Files
The following programs and applications can open, edit, and work with Garmin FIT Course (Flexible and Interoperable Data Transfer) (.fit) files exported from OSM2CDR:
Format specifications
- Proprietary format
- 2D only
- Lossless (no quality loss)
- No attributes
- Output: 1 file
- A Garmin FIT Course file: route vertices as trackpoints (lat/lon/time) in semicircles with CRC-16; route geometry only (no HR/cadence/power), downsampled to 10,000 points.
Who Uses FIT Maps
How to Export FIT
How to Open After Export
- Garmin Edge, Forerunner, Fenix — connect the device over USB and copy the .fit into the Garmin/Courses folder (on some models, NewFiles); after unplugging, the route appears in the courses section.
- Garmin Connect Mobile — "Training → Courses → Import", then send it to the watch or bike computer over Bluetooth, without a cable.
- Strava — upload it as a route into "My Routes"; from there the track goes to the device if synchronization is set up.
- Wahoo ELEMNT, Bryton, Polar — import through the vendor app or copy into the routes folder on the device: these units read FIT Course.
- GPSBabel — gpsbabel -i garmin_fit -f route.fit -o gpx -F route.gpx turns the course into GPX if you need a format you can read with your own eyes.
Popular maps in FIT
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