GpxFix Blog

FIT to GPX: Why Your Garmin File Is a .fit and How to Convert It

By Roy Lachica on October 22, 2026. Last updated October 22, 2026.

You exported your workout expecting a GPX file and ended up with something called activity.fit that no website seems to want and no text editor can open. FIT is the format your watch or bike computer actually records in, and it is the format Strava hands back when you ask for the original file. Here is what a FIT file is, why you keep running into one, and what you gain by turning it into a GPX.

What is a FIT file

FIT stands for Flexible and Interoperable Data Transfer, a compact binary format created by Garmin and now used by practically every serious fitness device, Garmin, Wahoo, COROS, Suunto, Polar, Zwift and more. Unlike GPX and TCX, which are text based XML, a FIT file is a stream of binary records. That is exactly why devices like it, it is small, fast to write, and it can carry far more than a track: sessions, laps, sport and sub-sport type, heart rate, cadence, power, temperature, device information and manufacturer-specific developer fields.

Why you end up with a FIT file

• Strava Export Original: Strava gives you back the file that was uploaded, not a converted one. If your watch synced a FIT file, Export Original returns a FIT file.
• Garmin Connect: the Export Original option on an activity gives you the raw FIT file from the device, which is the most complete version of the recording that exists.
• Bulk data downloads: account-wide archive requests from Garmin, Strava, Wahoo or COROS typically contain hundreds of FIT files rather than GPX.
• Reading the files off the device: plug a Garmin in over USB and the activity folder is full of .fit files, that is the native storage format.

Why you cannot just open it and look

A GPX or TCX file is XML, so you can open it, read the coordinates and even hand-edit a bad value. Open a FIT file in a text editor and you get binary noise. Fixing anything by hand is out of the question, and most route planners, mapping sites, race organiser upload forms and GPS repair tools will not accept it. Converting to GPX turns an opaque blob into something readable, editable and widely supported.

What survives the conversion, and what does not

A good FIT to GPX conversion keeps everything that matters for training: latitude, longitude, elevation, timestamps, heart rate, cadence and power, written into the standard Garmin trackpoint extension so other platforms can still read them. The sport type recorded in the FIT session is carried over as the GPX track type, which matters more than people expect, see why setting the correct activity type is essential.

What does not survive is the device-specific extra: developer fields, detailed lap and session metrics, recording events, running dynamics, and whatever proprietary channels your particular device writes. GPX simply has nowhere to put most of it. If you want a permanent archive of a race, keep the original FIT file alongside the GPX you work with, the FIT is always the richer record.

How GpxFix handles FIT files

There is no separate conversion step. Drop a .fit file into GpxFix exactly as you would a GPX. It is detected automatically, both by file extension and by inspecting the file header, so a FIT file that was renamed or downloaded with an odd extension is still recognised. GpxFix decodes it with the official Garmin FIT SDK, converts it to GPX in memory, and reports how many track points were converted before any repair work starts. From that point on every tool behaves exactly as it does for a normal GPX upload, and the file you download at the end is a standard GPX.

FIT files are also accepted wherever a second file is needed: as the file to combine with another activity, and as the reference file for repairing a workout from a reference GPX.

When you should keep the FIT instead

If the destination explicitly wants FIT, convert nothing. Uploading the original FIT to Strava or Garmin Connect gives you the richest possible activity, with laps, running dynamics and device metrics intact. Convert when the tool you are feeding needs GPX, when you want to inspect or repair the data, or when you want one consistent format across a whole library of files.

Frequently asked questions

Can I open a FIT file in Notepad or Excel?

No. FIT is binary, so a text editor shows unreadable characters and a spreadsheet cannot parse it. You need a tool that decodes the format, and converting to GPX is the simplest way to get something you can actually read.

Does converting FIT to GPX lose my heart rate or power data?

It should not. GpxFix writes heart rate, cadence and power into the standard GPX trackpoint extension during conversion. What is lost is device-specific extras such as developer fields and detailed lap metrics, which have no equivalent in GPX.

Is FIT or GPX more accurate?

Neither, they are containers for the same recording. FIT holds more channels, GPX is more portable. How accurate your track is depends on the device and the conditions, not the file format, see how to get accurate GPS and heart rate data.

Can I upload the converted GPX back to Strava?

Yes, Strava accepts GPX uploads. Note that it arrives as a new activity, so if you are uploading a corrected version of something already on Strava you will need to delete the original, otherwise duplicate detection will refuse the upload.

Got a .fit file you need converted or cleaned up? Drop it into GpxFix and it is handled automatically. Related reading: converting TCX to GPX and how to download a GPX file from Strava, Garmin, Komoot and others.