Update or Add New Maps to Your Sat Nav / GPS for Free (2026 Guide)

GPS map updates from manufacturers can cost £50–100+ per year. This guide shows you how to update your Garmin sat nav with the latest maps completely free using OpenStreetMap data, which is often more current than official maps.

Garmin maps are simple .img files (files with .img extension). So updating or adding maps is as simple as copying and pasting a file, which has to be named gmapprom.img or gmapsupp.img. In some places, you may find locked files, but there are tools to unlock those.

An additional option (but not free) is to purchase official maps from Garmin’s website. The cost in the UK (Europe map) is £49.99 for a single update or £74.99 for a LifeTime update (updates forever). If your GPS has LMT in the description is because LifeTime updates are included already (no extra charge). Once you get this, you install Garmin software from their website and you get the updates whenever you want.

But because we like free stuff, these are the steps:

What You’ll Need

Step 1. Connect Your Sat Nav

You need a USB cable to connect your Garmin sat nav to your computer. Which type depends on your model:

• Mini USB – older models (nüvi series, Drive 53, most pre-2022 devices). Pick one up for a few dollars: UGREEN Mini USB cable.
• USB-C – newer models (DriveSmart 66, 76, 86, DriveCam 76 and anything from 2022 onwards). A good option: Anker USB-C cable (2-pack).

Once connected, your sat nav should appear as an external drive on your computer — just like a USB stick.

2026 Update: Newer Garmin models (2020+) support WiFi map updates through Garmin Express, but the manual method below still works and gives you access to more map options — particularly useful if you travel to regions not covered by your device’s built-in maps.

Step 2. Find Your Map

I recommend using OpenStreetMap (OSM), which is updated daily by millions of contributors worldwide and often includes roads and locations missing from official Garmin maps.

Open Street Map (OSM) is the most used and globally recognised map source. They are free, created and updated by users and volunteers across the World.

The easiest thing to do is to find the map of your interest ready to use in .img format. So select your map from this link (once you find the one you need, click on the Provider column), only make sure that it says Yes in the Routable column. In my case, I wanted France, so I downloaded the map from the following website. There, you click on Europe Maps and then Benelux & France.

That’s it! Your browser will start downloading a .zip (if it is compressed) or a .img file. In my case, the file is called “Benelux & France-IMG-UL.zip“, and it is around 600MB.

Clarification: If you cannot find your map in the link above, follow the following steps:

1. Go to http://garmin.openstreetmap.nl/
2. In “Choose a predefined country” select Thailand
3. Click “Download map now”
4. Select only the file “osm_generic_gmapsupp.zip” to download.
5. Unzip the file above
6. Copy the unzipped file (gmapsupp.img) to your SD card

Alternative Map Sources (Advanced Users):

• HERE Maps (formerly NAVTEQ)
• MapSource compatible files
• Regional government mapping data

[Only for advanced users]: Browse the OSM website or other providers to find more specific maps. If your map has .osm extension, use one of these tools to convert it to .img. Mkgmap is a good one.

Step 3. Copy Your Map to Your Sat Nav

You have two storage options, depending on your device’s available space:

Option A: Use your Sat Nav’s built-in memory

You can now just copy and paste your file to your device. Once connected to your computer, it will appear as an additional drive, as shown in the image below.

You may not have enough space on your device, but you can remove some files and replace the existing map. You can always make a backup and copy the files to your computer.

gmapprom.img is the pre-installed map, so you can just replace it. gmapbmap.img is the base map containing only large roads and larger cities, not really suitable for routing. You could delete it but as it is only about 50 MB you wouldn’t gain much space. You can also delete some of the voice files to make room. These probably contain lots of different voices and languages (files with .sum and .vpm extensions) that you never use, so they may take up quite a bit of space. They should all be in the Garmin\Voice directory. This is also only around 50MB. Another option would be to go to garmin.openstreetmap.nl and select only the files you are interested in and see if the generated map fits on your device.

Option B: Use an external SD card

If you do not want to remove or touch the original maps (the ones that came when you bought your device), you can play it safe and use an external SD card. You only need to create a folder called Garmin and copy your .img file into this directory.

Storage Requirements (2026):

• Single country map: 1–3 GB
• Europe maps: 8–12 GB
• North America: 6–8 GB
• World maps: 15–20 GB
• We recommend a 64GB card — plenty of room for multiple regions and they cost under $10

A SanDisk 64GB microSD card is around $9 on Amazon and will handle every map you throw at it. Older Garmin models (pre-2012) may only accept up to 4GB — check your manual if you have a very old device. The card needs to be formatted as FAT32 before use (Windows, Mac).

Step 4. Check Your New Map in Your Sat Nav

To check if the map was copied correctly and is ready to use, follow these steps:

• Disconnect your Sat Nav from the computer
• Turn it on and click on Tools (bottom right corner)
• Click on Settings, then on Map, and then on Map Info.

You should now see your new map, as the image below:

If Maps Don’t Appear:

1. Check the file has a .img extension
2. Make sure the map file is in the correct folder (Garmin/ on the SD card, or the root Garmin/ folder on the device)
3. Restart the device completely (hold power button for 10 seconds)
4. Check that the file is named gmapsupp.img (for SD card) or gmapprom.img (for internal storage)
5. Verify the SD card is formatted as FAT32, not exFAT or NTFS

Device Compatibility

This method works with most Garmin devices from 2010 onwards, including:

• nüvi series
• DriveSmart series (51, 55, 61, 65, 66, 76, 86)
• Drive series (52, 53)
• DriveCam 76
• RV series

New devices can load multiple “*.img” files. If you want to have more maps on your device, you can rename the maps file in
gmapprom.img (original map/ or renamed new map), gmapsupp.img (2nd map), gmapprom1.img (3rd map), etc.

Do You Still Need a Dedicated Sat Nav?

If you’re reading this because your old sat nav is struggling, it’s worth asking whether a phone with Google Maps or Waze might be enough. We’ve used both for years, and there are genuine reasons to keep a dedicated device:

• No data needed – Garmin maps work offline, which is a big deal when driving through rural France or the Scottish Highlands with no signal. Phone maps can work offline too, but it takes planning and the experience is clunkier.
• Battery – your phone stays charged for music, calls, and emergencies instead of draining itself on navigation.
• Abroad without roaming – if you don’t have a roaming plan, a sat nav just works. No need to download offline maps in advance or worry about data charges.
• Bigger, purpose-built screen – a 6″ or 7″ Garmin mounted at eye level is easier to glance at than a phone wedged in a cup holder.

On the other hand, if you only drive locally and always have data signal, your phone is probably fine. But for road trips — especially abroad — a dedicated sat nav still earns its place on the windscreen. The current Garmin models all come with free lifetime map updates built in, so you won’t need to follow this guide for a new device.

Recommended Garmin Sat Navs (2026)

If your current device is more than 5–6 years old, a new Garmin with free lifetime maps may actually be better value than fighting with manual map updates. All of the models below include free map updates for life, live traffic, and driver alerts.

The DriveSmart 66 is what we’d recommend for most people — it hits the sweet spot between screen size, features, and price. If you want something more basic, the Drive 53 does the job at nearly half the price.

Keeping Maps Updated

OpenStreetMap releases new data monthly. Set a calendar reminder to download fresh maps every 3–6 months for the most current road information. If you drive in a country where roads change often (new motorways, roundabouts, one-way systems), quarterly updates are worth the 10 minutes it takes.

Frequently Asked Questions

Will adding custom maps void my Garmin warranty?

No. Adding or replacing map files does not void your Garmin warranty. You’re simply copying a file to the device’s storage — it’s no different from adding music or photos to a USB drive. You can always restore the original maps by copying them back.

Can I have both official Garmin maps and OpenStreetMap maps on the same device?

Yes. Your device can store multiple map sets. Keep the official maps on internal storage and load the OSM maps onto an SD card as gmapsupp.img. You can switch between them in Settings > Map > Map Info.

How often should I update my free maps?

Every 3–6 months is a good rhythm. OpenStreetMap data is updated continuously by volunteers, but downloading new maps quarterly strikes a good balance between accuracy and effort.

Can I use Google Maps on a Garmin sat nav?

No — Garmin devices run their own operating system and can’t install apps like Google Maps or Waze. However, you can use OpenStreetMap data (which Google Maps also draws from in many regions) by following the steps in this guide. The end result is very similar coverage.

Are OpenStreetMap maps accurate enough for driving?

In most of Europe, North America, and popular travel destinations — yes. OSM is maintained by millions of contributors and is often more up to date than official Garmin maps, especially for newer roads and roundabouts. Coverage can be thinner in very remote or less-visited regions of Africa and Central Asia, but for the vast majority of driving, OSM maps are excellent.

What size SD card do I need for Garmin maps?

A 64GB microSD card (around $9) is more than enough for most users. A full Europe map is roughly 8–12 GB, so 64GB lets you store multiple continents with room to spare. Older Garmin models (pre-2012) may only support cards up to 4GB or 8GB — check your device manual.

Do free maps include speed cameras and points of interest?

OpenStreetMap data includes points of interest (restaurants, petrol stations, hotels, etc.) but does not include speed camera locations. For speed cameras, you can download separate POI files from community sites and load them onto your Garmin in the POI folder — search for “Garmin speed camera POI” for your country.

Will this method work on TomTom or other sat nav brands?

This guide is specifically for Garmin devices, which use .img map files. TomTom uses a different format and a different update process. Some other brands (like Navman) can also use Garmin-format .img files, but check your device’s documentation first.

Additional Tips and Information

• Do not forget to visit our “Best Travel Gadgets” post to find other useful artefacts for your trip!
• If you’re planning a road trip, we recommend Skyscanner for searching for flights. For car hire, we use DiscoverCars — they compare prices across all the major rental companies and local agencies, which are often much cheaper than the big names like Europcar and Hertz.
• Are you still having problems with your maps? Please ask for help here.

Support Us

A small donation would help us to keep travelling and providing the best advice we can. Simply use this link from Buy Me A Coffee for that.