Do I Need OS Maps on My GPS if I Already Have a Premium OS Maps Subscription?
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This is one of the most common questions we get asked. Many walkers already use the OS Maps app on their phone and assume that their subscription includes OS mapping for their GPS device as well. The reality is a bit different — and understanding how it works can save you money and frustration.
Here’s a straightforward guide to what your OS subscription gives you, what it doesn’t, and when you might still want full OS mapping on your GPS.
What Your OS Premium Subscription Actually Covers
A premium OS Maps subscription gives you full Ordnance Survey mapping inside the OS app on your phone, tablet, and computer. It’s excellent for:
- Planning walks
- Plotting GPX routes
- Downloading offline maps to your phone
- Printing paper maps
But the important bit is this:
OS Maps app mapping does not transfer to a GPS device or GPS watch.
Nothing from your OS subscription can be installed on a Garmin outdoor GPS, a Garmin watch, a Suunto watch, or a TwoNav device. The only thing you can transfer is the route/track/course you’ve created - not the OS map itself.
So your GPS will show the line of your walk, but the background map will depend entirely on what mapping is built into the unit.
Why OS Maps Don’t Work on GPS Devices
Each GPS brand uses its own mapping format:
- Garmin uses TopoActive as standard, plus optional OS map bundles or OS map cards.
- Suunto watches use global topo maps (not OS mapping).
- TwoNav devices can be bought with OS mapping preloaded or you can download them.
OS Maps cannot be copied over because Ordnance Survey licenses digital mapping separately for each platform. A subscription on your phone doesn’t unlock OS mapping on a handheld GPS or watch.
So What Mapping Do You Get on a GPS?
Here’s the quick breakdown.
Garmin Outdoor GPS Units
Every Garmin handheld comes with TopoActive Europe mapping pre-installed. It’s routable, up-to-date, and perfectly good for most walking.
If you want full OS maps on a Garmin handheld, you must choose:
- A GPS + OS Map Bundle at checkout.
These are Topo Pro OS Map Card (1:50k or 1:25k), which only works on Garmin handheld GPS units.
Top tip:
If OS mapping is important to you, it’s usually cheaper to buy the GPS + map bundle rather than adding a map card later.
Garmin Watches
This one often surprises people:
You cannot install OS maps on any Garmin watch.
Even premium models like the Fenix and Epix use Garmin’s own topo mapping. It’s clear, detailed, and perfectly adequate for navigation, but it isn’t OS mapping.
Your OS subscription won't change that.
Suunto Watches
All colour-screen Suunto watches use their own Suunto global topo mapping. Again:
- You can transfer your GPX route from OS Maps,
- But you cannot load OS mapping onto a Suunto watch.
TwoNav GPS Units
TwoNav give you the option to purchase units with OS mapping preloaded or you can download them later.
If OS mapping is important for your walking, this is a strong option - especially because the mapping is properly integrated and works brilliantly on the large TwoNav screens.
Should You Add OS Mapping to Your GPS?
Here’s the honest breakdown:
Choose OS Mapping on Your GPS If:
- You regularly walk in the hills or mountains
- You rely on OS symbols and terrain detail
- You prefer navigating visually rather than following a line
- You want the same look and feel as your paper map
In these cases, OS mapping on the unit pays for itself in confidence and ease of use.
TopoActive or Suunto Maps Are Usually Enough If:
- You’re following a GPX route most of the time
- You're walking low-level trails
- You mainly want a breadcrumb line and accurate position
- You want to keep your setup affordable
For many Outdoor GPS Shop customers, the free mapping included is absolutely fine.
So… Do You Need OS Mapping on Your GPS?
If you’re happy following a GPX line:
You don’t need OS maps on your GPS.
Your OS subscription lets you plan routes easily, and the GPS will follow them perfectly on its standard maps.
If you want full OS detail on the device itself:
You do need to buy OS maps for the GPS unit.
Your subscription doesn’t cover it.
Quick Recommendations by Device Type
Garmin Handheld GPS (e.g., Montana, GPSMAP, eTrex)
- OS mapping optional — choose the bundle at checkout if you want OS detail.
Garmin Watches (Fenix, Epix, Forerunner etc.)
- No OS mapping available — use the built-in topo maps.
Suunto Watches
- No OS mapping available — Suunto’s own topo maps only.
TwoNav Handhelds
- You can buy OS mapping preloaded — a good option for UK walkers wanting proper OS cartography.
Final Thoughts
Your OS Maps subscription is brilliant for planning and navigating on your phone - but it does not provide OS mapping for Garmin, Suunto or TwoNav devices. It only sends the route to the GPS.
If you prefer fuller map detail on the device itself, choose the OS mapping option when buying your GPS, especially as bundles are usually the best-value route.
If TopoActive or equivalent maps meet your needs, stick with those and enjoy the saving.
