Why Convert FIT to TCX?
TCX (Training Center XML) is Garmin's XML-based format that predates FIT. While FIT is more compact and feature-rich, TCX remains widely supported by training platforms like Polar Flow, Fitbit, and some versions of Strava that don't accept FIT uploads directly. TCX files are human-readable XML, making them easier to inspect and edit manually. This converter preserves all compatible data fields — GPS, heart rate, cadence, power, speed, distance, elevation, and timestamps — while converting from the binary FIT format to structured XML. The conversion runs entirely in your browser for complete data privacy.
FIT is Garmin's current binary format — compact, fast, and capable of storing hundreds of data field types. TCX (Training Center XML) is an older Garmin XML standard from the early 2000s that predates FIT. Although FIT has superseded TCX for modern Garmin devices, TCX remains the import standard for several training platforms and older fitness software. Converting FIT to TCX is therefore a compatibility step rather than a data upgrade — you trade FIT's efficiency and richness for TCX's broader software support.
What Data Is Preserved in the TCX Output?
The TCX output includes all fields the TCX 2.0 specification supports: GPS coordinates (latitude and longitude), elevation in metres, cumulative distance, timestamps, heart rate, cadence, speed, and power. Speed and power are written using the Garmin TCX ActivityExtension namespace, which is recognised by Polar Flow, TrainingPeaks, Garmin Connect, and most platforms that accept TCX files with extended data.
What data is preserved?
- GPS coordinates
- Elevation
- Timestamps
- Heart rate
- Cadence
- Distance
- Speed and power (via TCX ActivityExtension)
What Gets Lost in the Conversion?
FIT files can store hundreds of proprietary data fields that have no TCX equivalent: body battery, respiration rate, Pulse Ox (SpO2), ground contact time, vertical oscillation, stride length, left/right pedal balance, and device-specific Garmin Dynamics metrics. These fields are silently dropped during conversion. If your analysis depends on any of these fields, export to CSV instead — the FIT-to-CSV converter retains every field it can extract from the FIT file.
How to Use This Converter
Upload your .fit file using the dropzone above — files up to 50 MB are supported. The conversion runs locally in your browser; your activity data is never sent to a server. The resulting .tcx file downloads automatically and can be imported directly into Polar Flow, Fitbit, TrainingPeaks, or any other TCX-compatible platform. If a platform asks for the activity type during import, you may need to select it manually — TCX does carry the sport type in the Activity element, but some platforms ignore it on import.
Common Use Cases
The most common reason athletes convert FIT to TCX is to import activities into Polar Flow — Polar's platform accepts TCX but not FIT files from other vendors. TrainingPeaks also historically preferred TCX for third-party device imports. Athletes using older fitness software like SportTracks Desktop edition (which still has an active user base) also need TCX, as these applications predate FIT's widespread adoption.
Coaches who receive activities from athletes using a variety of devices often convert everything to TCX for consistent import into a coaching platform. TCX's human-readable XML structure also makes it useful when athletes need to inspect or edit activity data — correcting a spurious GPS spike or adjusting a lap split is straightforward in any text editor, something that requires specialist binary tools with FIT files.
vs. Exporting TCX Directly from Garmin Connect
Garmin Connect lets you export any synced activity as TCX from the activity detail page (three-dot menu → Export Original → TCX). If your activity is already in Garmin Connect, that is the simplest approach. Use this converter when you have a raw .fit file that has not been synced — for example, activities from a device with a full memory, a borrowed device, or activities you want to share without uploading to a cloud account.
Common Issues
If the imported TCX shows incorrect GPS coordinates, confirm in the TCX file itself that latitude and longitude values are in decimal degrees (e.g., 59.9 not 713,000,000) — this converter handles Garmin's semicircle format automatically, but verify if a platform shows unexpected location data. If a platform rejects the TCX file, try exporting to GPX instead — GPX has even wider platform compatibility. Multi-sport FIT files (triathlon) produce a single-sport TCX, which some platforms may not handle.
Frequently Asked Questions
Does the TCX output preserve lap data?
Lap data from the FIT file is not included in the TCX output. TCX supports lap structures, but mapping each FIT lap record to TCX laps would require inferring lap boundaries from the trackpoint timestamps, which can produce inconsistent results across device manufacturers. The output is a single-lap TCX — platforms that rely on lap splits (like TrainingPeaks) will show the entire activity as one lap.
Can I convert FIT files from any device?
Yes — FIT is an open protocol used by Garmin, Wahoo, Suunto, Polar Vantage series, Zwift, and many other platforms. This converter works with any standard FIT file regardless of the originating device. Device-specific proprietary fields (such as Garmin's running dynamics or Wahoo's internal metrics) are ignored during conversion since they have no TCX equivalent.