Our best-selling product is the OS Premium Plus Subscription. This following article is based around the maps available on that subscription, but the concepts work for all of our subscriptions.


Size of data


First up, lets consider the size of the data. The OS Premium Plus contains all of Great Britain in:

OS 1:25,000 SD
OS 1:25,000 HD
OS 1:50,000 SD
OS 1:50,000 HD
OS 1:10,000 OS Open Map Local

There are further maps, such as overview, height, find place data etc, but the above 5 map types are the maps that need to be considered in terms of storage space required.


The following link gives the sizes:

Sizes of map data sets


A quick tot-up, and you can see for a complete download of OS Premium Plus you will need approximately 80GBs


80 isn’t a very big number


Actually, it is. A standard DVD can hold about 4.5GB, so this would ship on about 20 DVDs!


Most new mobile phones come with 32 or 64 GB of internal storage. You can often pay for more storage when buying the phone (128 and 256Gb are now quite common), and on some Android phones you can simply add an SD card.


The point being, on many mobile setups, if you just try to download everything, you will soon run out of space. Even modern laptops often come with a 256GB internal storage, so downloading all of this data will soon fill up a considerable part of your hard-drive.


But I have plenty of storage / good internet


So, feel free to download all of the map data. Just set it going.


But even if you have the storage, given you have paid for it, do you want to download mapping that you may never use? Read on.


Map Streaming


Map Streaming can be thought of as map download on demand. As tiles are needed, if they aren’t local to your machine, OMN will download them. If you are only say using your laptop at home where you always have a good Wi-Fi connection, why download any mapping, when it will just stream into place when/if required?


Map-Streaming won't work if you don't have an internet connection, which is par for the course on many hills. So for your mobile device you will want to download mapping before setting off.


Download the basics


We advise most users to download the following products – they don’t take much space, but give you a great set of overview tools:

GB Road Atlas: contains OS GB Map (1:1,000,000 scale) and OS Road Map (1:250,000 scale)

GB Height Data


Pop into the Find screen, and download the Find Place data – it will prompt you on first use.


More about Map Downloading


SD vs HD


The OS Premium Plus subscription contains both High Definition and Standard Definition maps. The HD maps take up a lot more storage space.


HD print much nicer. On a high-resolution mobile screen, HD render much nicer. On a lower resolution screen, the difference is not so pronounced, so this is very personal.


We have demo maps available of all of the map types, so on your device, open up My Maps / Map Management (Mobiles), and select a map from the demo maps. Then you can flick back and forth between the different maps.


If you have the storage space, HD is probably the way to go.


The size differences between SD and HD are significant.

OS 1:25,000 SD is 7 GB, versus 27 GB for the HD
OS 1:50,000 SD is 3.3 GB versus 8 GB for HD


OS 1:50,000 SD


At just 3.3GB, this is the baby of the set of major maps, yet once downloaded, it’s the equivalent of 204 paper Landranger maps. A lot of users download this as a catch-all, “I have the full country in my pocket.”


Some users, if they have the space opt for the HD version, but that uses almost 3 times as much storage.


We split the GB into 10 regions, and some users just choose to download say 4-6 regions.


We often see users download the SD on their mobile, but HD on their PC.


Think Geographically


When it comes to Explorer mapping and the 1:10,000 OS Vector Map Local, it pays to think geographically and if you want SD/HD or a combination of both.


Use this link to identify which 100km square you wish to download:

http://apd.anquet.com/maplegends/NAT_GRID_GB.gif


The squares differ hugely in size of data – the more sea, the smaller the download.


You can always come back and download more.


Warning: Data usage on mobiles


Whilst you can download more data at any-time, if you are on a metered mobile phone contract, these often come with say 2 or 4GB of monthly data allowance – so you can see you can blow through that very quickly.  You can control this on mobiles in Settings->Data


Your decisions are not set in stone


Whilst you have a valid subscription, you can always download more mapping. So before leaving your home area for a trip, you can always utilise your home Wi-Fi and download some more mapping. Or whilst away, pop into a coffee shop and download a bit more or use the hotel Wi-Fi. Or of course if you have a capable mobile data plan, download via your mobile operator.