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TCX to FIT Converter
Move a library of old .tcx activities — exported by Garmin Training Center, an early Edge or legacy coaching software — into FIT, the format every modern device and platform prefers. Garmin Connect, Zwift and Strava all take FIT first, laps and heart rate come along, and the conversion runs entirely on your machine.
or click to browse — the output will be FIT; format is detected automatically
How to convert to FIT
- 1
Drop your file
Drag a FIT, GPX or TCX file onto the box above, or click it to browse. The source format is detected automatically from the file contents.
- 2
Wait a beat
The conversion runs in a background worker on your device. Typical activities finish in well under a second; even 50 MB files process without freezing the page.
- 3
Check the preview
Distance, duration, ascent and average heart rate are shown alongside a map of the converted track, so you can confirm nothing was lost before downloading.
- 4
Download
Click the download button and the .fit file is saved straight from memory. Nothing was uploaded, so there is nothing to clean up.
What is a TCX file?
TCX (Training Center XML) is Garmin's older training format, introduced with Garmin Training Center in the mid-2000s and later extended by Strava and others. Like GPX it is XML, but TCX is structured around workouts rather than raw tracks: activities contain laps, laps contain tracks, and the schema natively understands training concepts — total time, distance, calories, heart rate zones and cadence — that plain GPX leaves to extensions.
Today TCX sits between two worlds: modern Garmin devices write FIT, while Strava's uploader still accepts TCX as a first-class citizen and many legacy coaching tools (TrainingPeaks imports, older Polar flows, Golden Cheetah archives) expect it. Converting into or out of TCX is usually about keeping lap structure and summary data intact while crossing between those generations of software.
What is a FIT file?
FIT (Flexible and Interoperable Data Transfer) is the binary activity format created by Garmin and maintained by the FIT Coalition. Every Garmin watch, cycling computer and trainer writes .fit files, and brands like Wahoo, Zwift, COROS, Suunto and Bryton use it too. Because it is a compact binary format, a FIT file can hold a full season of second-by-second records — GPS position, altitude, heart rate, cadence, power, laps and sessions — in a fraction of the space the same data needs as XML.
The trade-off for that compactness is compatibility. FIT is a device format: desktop tools, older websites, GIS software and many coaching platforms either cannot open it at all or only import it through a vendor uploader. That is the moment most people go looking for a converter — and why this page exists. A faithful conversion preserves every sample your device recorded, including the extension channels (heart rate, cadence, power) that generic GPS formats often drop.
Why convert TCX to FIT?
TCX files tend to sit in old folders for one reason: they came from software that time moved past. Garmin Training Center, early Edge exports and late-2000s coaching tools wrote TCX because that was the training format of the era. The platforms those files now need to reach — a modern Garmin watch, Garmin Connect, Zwift, Strava — all speak FIT natively and treat it as the primary upload format: full fidelity, smallest file, first in every compatibility list.
Consolidation is the other driver. A training history split between TCX, FIT and the odd GPX is a maintenance headache; converting the TCX portion to FIT leaves one format that every current platform ingests without a compatibility note. FIT is also the only one of the three your devices both write and re-read, which makes it the natural hub for a mixed archive.
Size comes free with that. The same activity as FIT is typically several times smaller than its TCX original — worth noticing when an entire season, or decade, of history has to move somewhere in bulk, whether that is a cloud drive, a club archive or a long upload queue.
What carries over from the 2000s
The training structure translates cleanly in the modern direction too. Each TCX lap becomes a FIT lap message with its timing and totals, per-point heart rate and cadence map to their native channels, and TPX power becomes the power channel every current platform graphs. A Training Center-era interval session arrives in Connect with its laps intact.
What stays behind is mostly metadata TCX invented for itself: creator and equipment notes, plus vendor-specific extension elements (Strava's own namespace, uncommon sensor extensions) that have no slot in a FIT activity file — dropped openly rather than approximated. The recording itself is never touched: a 2008 file with sparse, drifted GPS points converts exactly as recorded, flaws included.
Your files never leave this browser
This tool — like every tool on this site — runs entirely as client-side JavaScript. The file you drop is parsed in a Web Worker on your own device, converted in memory and handed straight back to you as a download. There is no upload endpoint, no server-side conversion service and no temporary storage: you can watch the network tab in your browser's developer tools and confirm that no file bytes are transmitted anywhere.
That matters more with fitness data than with most files. A GPS track is a precise log of where you were, at what time, and how hard your heart was working — home address, training habits, favorite routes and race schedule all in one file. Keeping conversion on-device means third-party converters never get a copy of that log, and the tool keeps working identically on a plane, in a basement, or anywhere else without signal.
Frequently asked questions
Yes. Connect's manual upload accepts FIT activity files, and a converted TCX arrives as a normal activity with its laps, heart rate and full track. This is the standard route for getting Training Center-era history onto your Connect calendar without re-recording or screenshotting anything.