Using GMapTool to convert OSM Topo maps for Garmin

As of 27 September 2018 these instructions do not work for downloading map files from on older Garmin devices. I’ve reached out to for support.

A much simpler process for loading custom maps can be found here:

I’ve updated the guide on 26 September 2018 with pictures and better instructions. However, it appears that there is a problem in the OpenStreetMap files from GMapTool.EU. The GMapTool converter program functions properly but there is “missing” information on the combined gmapsupp.img file. I checked this file using JaVaWa Device Manager for Garmin and it shows “0 maps found” in the combined IMG file.

There are two alternatives until a fix can be found. Followi this guide:
use pre-compiled maps (there is no customization) of the US roughly based on LAT and LONG location data. It isn’t as pretty as the OpenStreetMap files but it is working for now. Simply download the correct file size (500 mb, 1 gb, 2 gb, 4 gb) file based on your LAT and LONG, rename to “gmapsupp.img”, put this in the “GARMIN” folder on your MicroSD card, and load into your GPS.
The URL for downloading the pre-compiled IMG files can be found here:


Looking to add open source maps to your Garmin GPS and trying to use the GMapTool?

This should help convert OpenStreetMaps downloaded from to a format usable by older Garmin GPS devices (.img) using Windows as the OS. Older Garmin devices do not support multiple independent maps but do support multiple maps combined into the “.img” format. In this tutorial we will combine multiple OpenStreet maps using the GMapTool and uploading to a Garmin 60CSx.

The WIKI that helped with this post can be found here:

  1. Download GMapTool here:
  2. Install the GMapTool, put a shortcut on your desktop, and launch the program.
  3. Download map data here:
    1. For example, to use USA South Central TOPO map data, use this link for the map data page and the download link is at the bottom of the page.
  4. Using an unzip program (such as WinRAR), right-click on the .7z (7 zip) file and select “Extract to [folder name]“.
  5. Once extracted you’ll have another folder for your map region data. In this case “US_South_Central_OSM_Topo.gmap”.
  6. Open the “.gmap” folder and then open the sub folder labeled “Product1”. Verify that you have many folders with numbers as the folder name. In our case I am in “[directory]/US_South_Atlantic_OSM_Topo_v25a/US_South_Atlantic_OSM_Topo.gmap/Product1/” folder. Note that the GMAP program replaces backslashes “\” with forward slashes “/”.
  7. Make note of (copy) that folder path. For example, a full path for me would be “D:\Users\jball\Downloads\US_Northeast_OSM_Topo_v28\US_Northeast_OSM_Topo.gmap\Product1”
  8. Open GMapTool program. Select “Files” tab, select “Add Directories”. Paste the folder path in the “Filename” field. Update: you need to double click on the Product1 folder in the window. The GMap tool no longer navigates down directly to your pasted folder address. If you paste the address and double click on Product1, you should immediately see your many folders with numbers as folder names appear in the window.
  9. Click on the first folder, hold down shift, scroll to the bottom, and select your last folder. All folders should be highlighted.
  10. Click OK. You should see File Name, Size, and Mapset data.
  11. Click the “Join” tab. Click “Output file”, select a directory, and add “gmapsupp.img” to the end of the directory. You can also double-click on the elipses “…”, navigate to your desired directory, and in the filename field include “gmapsupp.img” as your filename. Click OK when finished.
    1. For example, mine is “D:/Users/[username[/Downloads/US_South_Atlantic_OSM_Topo_v25a/gmapsupp.img
  12. In the Mapset name field, give your mapset a name. I used “gmapsupp”.
  13. Click “Join all”.
    1. The program will now generate a gmapsupp.img file in the directory you chose. An output of the process will look similar to the screenshot below.
  14. Connect your Garmin GPS in mass storage mode. On my Garmin I had to navigate to “Menu –> Setup –> Interface –> USB Mass Storage”. *Note: I’ve had mixed results copying directly to the MicroSD card versus copying over mass storage mode. Mass storage mode is a lot slower but seems to guarantee results.
  15. Open your MicroSD card (via USB-connected Garmin GPS). Create a folder called “GARMIN” if it doesn’t exist.
  16. Open the “GARMIN” folder and copy/paste your gmapsupp.img file.
  17. If you need help changing your map use this tutorial:
  18. Once your map has been copied over, power off then power on your GPS. You will see a loading bar scroll across the bottom and, if your map has turn-by-turn navigation data you will also see a message about turn prompts.
    1. Drill down into your map settings using the tutorial from step 17. You should now see your map data folders. If you zoom out quite a bit you will also see your overlays for the region you selected.
  19. Enjoy your open source maps!



7 thoughts on “Using GMapTool to convert OSM Topo maps for Garmin”

  1. Hey John, when I copy the file name and try to paste it under the input directory file name I am getting nothing. It won’t even let me click ok. Any thoughts? Sounds similar to GoGayleGos problem.

  2. Hello John Ball, I have followed your instructions and copied the file “gmapsupp.img” into a directory on my Garmin 64s SD card but when I power on and off the Garmin does not see the file on the SD card. Am I missing a step that allows the garmin to recognize the sd card. My windows computer sees the sd card and sees the file on the sd card. I also previously installed a .exe topo file on the Garmin and it works fine. Any advice is appreciated.

    Thank you

    1. Not sure if this will help or not. I am using a 2GB SDcard formatted as FAT32.
      There may be a limitation on the size of the MicroSD card you can use in your GPS unit. I chose 2GB for comparability. Seems 4GB would work, 8GB is hit or miss, and anything over 8GB might not be recognized.

  3. I did not see a way to upload a screenshot here…if there’s a way, please advise, or feel free to contact me via my e-mail address. I also tried brute-forcing by manually adding all the files in those folders. While that seemed to work, when I uploaded to GPSr there were no maps (NOTE: I can view the maps on MapSource and BaseCamp, so they are on my computer). I even removed the other OSM maps from my SD card (e.g. tried using this map by itself), that didn’t work. I uploaded a piece of a different topo onto this SD card, that was successful. So it’s some combination of me, the GPSr, and these particular maps.

  4. I’m OK until I get to Step 8. When I copy/paste the path (all the way to “Product 1”), I don’t get a list of all the folders in the window (they are definitely there in the actual folder on my computer).

    I only get three lines that look like this:

    I tried selecting and combining all these, but got an error. Any idea what I’m doing wrong?

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