How to install detailed maps on an older Garmin – for (almost) free!

Maximise the functionality of your Garmin for navigation

This applies to the Garmin Edge 520/705/800/810 GPS devices

I recently helped out one Dittons Velo rider to install a map on her Garmin 810 before a trip to Mallorca. Whilst there, she intended to explore unknown countryside and hills. On her return she loaded a UK map. In three years of Garmin ownership, she admitted that she had never seen a decent map with road names on her Garmin!

If you’re a Garmin user (see list above), it’s likely you’re using the device with it’s very basic map. If all you ever want to do is record an activity – where you have been,  speed and other statistics – then it’s absolutely fine and you can stop reading now!

However, if you want to use your Garmin to navigate a route (there are plenty to download from the DV web site!) you’re going to need a better map; one with road names and more details!


openstreetmapbasemapAs shipped, the above Garmin units come with a “basemap” installed. If you zoom in to the map you see very few details apart from some main A-roads and rivers (compare the images)! On those devices apart from the 520 you can add a detailed map via a micro SD card (see image below).  Newer devices including the 820, 1000 and 1030 have a navigable Europe map factory installed. For 520 instructions see below.

The good news is that maps are easily available: options include purchasing maps on an SD card or via download, from Garmin for £35 (as of November 2018) or Ordinance Survey  1:50k Full Country SD Card for £109.99!

The Free map option…

Alternatively, if you have a microSD card with a capacity of 1GB or larger (I found one in an old phone), you can install the incredible and free OpenStreetMap map
You can buy an 8GB SD card for under £4 online – it doesn’t need to be a digital video, high speed SD etc card.

To install the map you simply need to download the map as a gmapsupp.img file and copy it to the microSD card in a folder named Garmin (there is not enough free space in the main memory). Make sure your computer is set to show file extensions.

sd slot

There are detailed instructions available to follow on the internet e.g.

You can even create custom maps at or download a range of ready-made maps for free at

The Edge 520 has no Micro SD slot and not enough internal memory to add a gmapsupp.img file. A hack is to replace the gmapbmap.img (Garmin base map) file found in the Garmin folder with a gmapsupp.img file that you then rename to gmapbmap.img after saving a backup of the original Garmin gmapbmap.img file.

If you are lucky enough to travel abroad to cycle, simply download and install a gmapsupp.img file for the destination country before you travel (remember to change it back on return to the UK!).file structure

With a 16GB microSD card I keep a number of gmapsupp.img files on the card and simply rename them when required (see screenshot). Note the current gmapsupp.img file in use is a custom area of South of England only.

Happy navigating!

David Matthews

November 2018