FIT is the file a Garmin watch or bike computer - and most Wahoo, Coros, Suunto, Polar and Hammerhead devices - writes for every ride, run and swim. This opens one without an account on the maker’s app: the route on a map, the headline numbers (distance, time, pace or speed, elevation gain, heart rate, power, cadence, calories), a chart for every channel the device recorded, and a table of laps. A multisport file shows each leg separately.
It also converts: GPX keeps the route, time, elevation, heart rate, cadence, temperature and power in the form Strava, Komoot and Garmin Connect read back, TCX keeps the laps too, and CSV gives every sample as a spreadsheet row. And it edits, like the FIT file tools people use before uploading: trim the minutes before you set off or after you stopped, move the clock of a watch set to the wrong time zone, change a ride logged as a run, remove heart rate, cadence, power or temperature, hide the GPS near your home at the start and finish, or repair a file cut short when the watch lost power. The file is read in the page. Apart from the reader code, fetched once when you open a file, the only thing fetched while you look is the map tiles, from OpenStreetMap, and you can turn the map off before opening a file so they are not fetched at all.
- How do I convert a FIT file to GPX?
- Open it here and press .gpx. The GPX has every GPS point with its time and elevation, plus heart rate, cadence, temperature and power where the device recorded them, so uploading it elsewhere keeps the data rather than just the line on the map. An indoor activity has no positions, so it has no GPX - the CSV still has everything.
- Why are some numbers missing?
- Because the device did not record them. A run without a chest strap or wrist sensor has no heart rate, and most running watches record no power. The page shows a chart only for a channel that is actually in the file.
- Which FIT files will it not open?
- Files that are not activities - device settings, daily step monitoring and workout plans are FIT files too - which are named as such rather than shown as an empty page. A file cut off partway through, which happens when a watch loses power or a transfer stops, is opened from the part that is complete, and Save repaired .fit makes a whole file of it.
- Is this like fitfiletools?
- It does the most used FIT file tools in one place, in your browser: trim, time adjust, sport change, removing heart rate, cadence, power or temperature, a privacy zone round the start and finish, repairing a file cut short, and converting to GPX, TCX or CSV. Each edit changes only what it says: every other message, including device and developer data from apps such as Stryd, is kept byte for byte, and the result passes FIT's own checksum. Joining two activities into one is not offered yet.
- Will Garmin Connect or Strava accept the edited file?
- They should: the edited file is an ordinary FIT file with a correct length and checksum, and Strava works out most figures from the samples. After trimming, the session's and laps' start, time, distance and start and end points are brought up to date, but averages and totals such as calories and climbing stay as the watch recorded them. Delete the original activity first, or the upload may be refused as a duplicate.