Free online TCX to KMZ converter

Some mapping and GPS applications accept KMZ but not Garmin’s TCX activity format, so a recorded ride, run, or route must be converted before it can be opened in Google Earth or shared as a map overlay. KMZ also packages the resulting KML in a compressed archive, making it more convenient to distribute as one file.

What the TCX format is

TCX, or Training Center XML, is an XML-based GPS exchange format originally associated with Garmin Training Center and Garmin devices. It stores activity data such as trackpoints, latitude and longitude, elevation, timestamps, distance, speed, heart rate, cadence, laps, and waypoints.

You commonly encounter .tcx files after exporting activities from Garmin Connect, Garmin watches, cycling computers, or training platforms that support Garmin-compatible exports. TCX is designed for workout analysis, so it can contain substantially more information than a map display needs.

What the KMZ format is

KMZ is a ZIP archive containing one or more KML files, normally with a main file named doc.kml. KML describes geographic features for programs such as Google Earth, including paths, placemarks, labels, styles, descriptions, and optional time data.

KMZ is useful when the destination application requires a single Google Earth-compatible file. ZIP compression reduces the size of the KML and allows related icons or image overlays to be included alongside it. A simple route conversion usually produces a KMZ containing only a line and its geographic coordinates.

How to actually convert TCX to KMZ

Using GPSBabel and a ZIP utility

GPSBabel is a suitable desktop converter because it reads Garmin Training Center XML and writes KML. Install GPSBabel, place the TCX file in a convenient folder, and run:

gpsbabel -i gtrnctr -f activity.tcx -o kml -F doc.kml

The gtrnctr input type identifies Garmin Training Center XML, while kml selects Google Earth’s XML output. Replace activity.tcx with the actual input filename. The command creates doc.kml.

Create the KMZ archive from that KML file. On macOS or Linux, use:

zip -j activity.kmz doc.kml

On Windows PowerShell, use:

Compress-Archive -Path doc.kml -DestinationPath activity.zip
Rename-Item activity.zip activity.kmz

The resulting activity.kmz can be opened in Google Earth Pro or another application that supports KMZ. If using the GPSBabel graphical interface, select the TCX/Garmin Training Center input format, choose the source file, select KML as the output format, export the KML, and then create the KMZ archive separately.

Using the website converter

For a conversion without installing software, 101convert.com can convert the file for free. Upload the .tcx file, select KMZ as the output format when available, run the conversion, and download the generated file.

Quality, compatibility, and limitations

TCX contains training metrics that KML does not represent consistently. A conversion normally preserves the route geometry and may preserve elevation or timestamps, but heart rate, cadence, power, laps, calories, and device-specific workout fields can be omitted or placed only in descriptive metadata.

Check the output in Google Earth after conversion. Confirm that the route is in the correct location, that elevation is enabled if needed, and that the start and end points are present. A TCX with multiple activities may export as several KML features; split the source file first if the destination requires one route.

A valid KMZ is a ZIP archive with a .kmz extension. For maximum compatibility, keep the main KML at the archive root and name it doc.kml; do not place it inside an extra directory. Renaming a KML file directly to .kmz does not perform the conversion.