The GDB file type is the Garmin Database file used by the Garmin MapSource application to store waypoints. The GDB file type is a proprietary way to store geographic information, and therefore the best way to convert a GDB file is in Garmin MapSource itself. However, because Garmin is a popular GPS manufacturer, many other applications, both stand-alone and Web-based, can convert the GDB file type to the more standard GPX file for use on a number of different GPS devices.
Launch MapSource from your "Programs" menu.
Click "File" and then "Open" and select your GDB file from your hard drive to open it in MapSource.
Click "File" and then "Save As" and set the "Save as Type" option to "GPS exchange Format (*.gpx)." Select a name and a location to save your GPX file to and press "Enter."
Navigate to the GPS Visualizer conversion web page (see Resources).
Select "Garmin Map Source GDB" from the "Input File Format" drop-down box.
Select "GPX XML" from the "Output File Format" drop-down box.
Click "Choose File" and select the GDB file on your hard drive. Click the "Convert the File" button to upload your GDB file and have the server convert it to GPX.
Click the provided download link to save the new GPX file to your hard drive.
Download and install GPSBabel from the developer's website (see Resources). GPSBabel is a free application that can convert between a number of common and obscure GPS file formats. Launch the application from your "Programs" menu when the installation is complete.
Select the file under "Input" as "Garmin MapSource - gdb" and under "Output" as "GPX XML" using the appropriate drop-down boxes. Check the "File" option for both sections.
Select your GDB file from your hard drive using the "File Name(s)" button under the "Input" section. Select a name and location to save the GPX file under the "Output" section. Click "Apply" to make the conversion.