Free OSM maps for Garmin

If you’d like to know how to download free Open Street Maps for any country then read on.

Garmin store maps on a microSD card installed in your unit. It’s possible to use OSMs instead of the Garmin supplied ones, and these are the same maps used by many route planning systems. The maps displayed on the Garmin are more attractive and informative than the Garmin ones. To download and install maps for anywhere in the world you can follow these instructions. Note that the screen shots shown here are from a Mac. On a Windows machine they will be slightly different.

1. Acquire/purchase a suitable microSD card.

They cost around £11 and come with an adapter that also allows them to be plugged into an SD card slot on your computer. You can buy them online, or at stores such as Tesco. You may want to check what size of card is supported by your model of Garmin. However, 16GB seems to work OK.

2. Download the map file for your desired country.

The simplest way to do this is to visit the website garmin.openstreetmap.nlYou should see a screen like the one below. To obtain a routeable map – one that will provide turn-by-turn navigation, and allow you to search for points of interest etc – select the Routeable Bicycle map type. Then, choose your country from the drop-down lists (e.g. Europe –>United Kingdom, in the example shown). Then, click on Download map now.

This will open another window (see below). Warning: do not be tempted to create large maps by selecting additional map tiles. If the file size exceeds 2GB then it will not copy onto the microSD card. It is simplest for most purposes to just load one country (or region) at a time.


3. You should now seen a screen similar to the one below. For a Garmin GPS unit you need to select the  file for loading directly onto the SD card of the GPS. Clicking the name should start the downloading, which can take several minutes as the files are quite large.


4. Locate the downloaded file and (if necessary) double-click it to unzip it, or use unzip or a similar program to extract the uncompressed map file. The uncompressed file will have the name gmapsupp.img. It is important that the file has the extension .img, but you can give it a more descriptive name if you wish. (For example, for the UK, you could call it UK.img, or France.img for France.) You may wish to check the file size at this point to ensure that it’s less than 2GB. Otherwise it will not copy onto the microSD card. (This is because the card is usually formatted with the file type FAT, used by Microsoft.) If you download using the method described here, and do not include additional tiles, then the file size should be OK.

Now you are ready to copy the file to the micro-SD card. This can be done in one of two ways: using an SD card slot on your computer (much faster than the other method because of the large file size), or by copying it directly to your Garmin unit (which is much slower because of the slow USB connection). Either should work OK, but I prefer the first method for convenience.

4.1 Using the SD card slot on your computer

Put the microSD card into its adapter and insert it into your computer’s SD card slot. You must ensure that there is a folder called GARMIN on the microSD card. (Note that the name must be all uppercase.) If there isn’t one then create it. Then copy the .img file into that GARMIN folder on the microSD card. Once copying has finished, unmount/eject the card from the computer and insert it into your Garmin.

4.2 Copying directly to your Garmin.

Insert the microSD card into your Garmin. Plug your Garmin into the computer using a USB cable. Wait for it to show as mounted. You should see two mounted devices on which you can create/copy files: the Garmin unit itself, and the microSD card. Make sure there is a folder called GARMIN (uppercase) on the microSD card. If it isn’t there then create one. Now copy your .img file into the GARMIN folder on the microSD card. Make sure it’s the microSD card that you copy it to. The copying may take quite a long time. Once it has finished, unmount/eject both the microSD card and Garmin unit from your computer, and unplug it.

5. Turn the Garmin ON. The newly installed map should be enabled. If it isn’t then you may need to use the Garmin settings to manually enable it. To test it, try loading a course for the country whose map you downloaded and then display it. The correct map should show up.  On the Garmin unit, the maps will show up with a name something like Openfietsmap Lite (GBR_18_11_2017). In the case of France, the GBR would be replaced by FRA. You should be able to store quite a few maps on a single microSD card.

 You can repeat the above steps for different countries, states etc. It’s useful to give the .img maps descriptive names so that you can keep track of them on your computer – maybe by placing them in a dedicated folder.


Roger Hubbold