How to get free routable maps into Garmin eTrex 20

This post will guide you how to get routable OpenStreetMap(OSM) maps into your Garmin eTrex 20 GPS unit. OSM maps are not comprehensive compare to other Garmin maps that you can purchase from Garmin but never the less they are free and you have the whole world to select for download.

Note: I have tested this on my Garmin eTrex 20 and i am sure that this method also works for Garmin eTrex 30 units as well.

Before you start, download mkgmap and make sure you have java installed into your system because mkgmap is a java based command program.


  1. Goto  Free routable maps for Garmin GPS devices and download the Garmin map (IMG format) of the region you need.
  2. Using mkgmap, give a description ID to your map so that you can identify the map from your Garmin eTrex 20 GPS device. You can disable it if you want to. The command is:

    java -Xmx512m -enableassertions -jar mkgmap.jar --draw-priority=10000 --transparent --gmapsupp --description=<your map name> <downloaded map file>.img
  3. mkgmap.jar will create a new file, gmapsupp.img. Rename this file to your choice and copy the file into your Garmin eTrex 20 GPS unit.
Note: Garmin eTrex 20 is able to support multiple IMG files with different filenames. From the Map setup in the device the name of the IMG file is reflected from the description ID set in step 2.

References or Credits:

  1. Free routable maps for Garmin GPS devices


  1. And where do I copy the map to on my Garmin? When I use Basecamp it doesn't work. Tries to load the whole map. The selection tool on Basecamp just crashes.

    1. Hi Brian,
      Copy the map (img extension) into the "Garmin" folder. You name the map file name differently.

  2. Hi there. This looks good - but I was hoping to find maps for France... Do you know of any as OpenStreetMap doesnt provide them?

    1. Hi, I could find the map of France for download. Go to and choose France from the Europe drop down list.

  3. This comment has been removed by the author.

  4. for some reason I cannot open the file after downloading it. any help??

  5. also I was trying to download the file and also have downloaded mkgmap


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