Storage and Verification

Use this page when you want to understand where downloaded map data is stored, why map sizes do not always match the total on disk, and when to use Verify Map Data.

What this page covers

where downloaded maps are stored
how Storage totals differ from map sizes shown in the list
what happens when map data is shared between areas
moving downloads to another storage location where supported
when to run Verify Map Data

Understand the two size views

Map Management shows size information in two different ways.

Storage shows the exact amount on disk

The Storage section shows the real amount of space currently used on your device.

Use this number when you want to know how much room OMN4 is taking up.

Map rows show the size for that map or area

In the Maps list, the size beside a map is the amount OMN4 treats as belonging to that map or area when you download it.

This keeps the map list useful when you are deciding what to save for offline use, but it does mean the numbers in the list do not always add up to the storage total.

Why the numbers can differ

Some downloaded map data is shared.

For example, if you download a large area and then add a smaller neighbouring area, part of the smaller area may already be covered by files you downloaded for the larger one.

That means:

the smaller area can still show its own download size in the map list
the total on disk may not increase by that full amount
deleting the smaller area may not free the full amount shown beside it

This is normal. OMN4 is avoiding duplicate storage where it can.

What happens when you remove a map or area

When you remove downloaded data, OMN4 tries to protect coverage that is still needed elsewhere.

If the selected map or area has data that is only used there, OMN4 can remove it directly.
If some of that data is also used by other downloaded areas, OMN4 warns that shared data is involved.
If you continue, OMN4 removes the part that can be safely removed without damaging coverage outside the selected area, unless you explicitly choose to include shared data.

This is why the amount removed can be smaller than the size shown in the map list.

Manage storage locations

Open Storage in Map Management to review where your downloaded map data is stored.

Depending on platform support, you can:

add another storage location with Add Location...
choose which location is used for new downloads
remove a storage location after confirmation
use Move to... on a supported map entry to move its downloaded data to another location

Some items shown under Other Storage are managed separately. For example, streamed map cache is not moved with the same action.

If you choose a slower drive or external location, map-related tasks may also feel slower in use.

Some map-related downloads are not ordinary map pictures but still use the same storage system.

This can include:

height data
downloadable search datasets for supported areas

These items can appear in the same storage and move workflow as other downloadable map entries when that action is available.

Verify downloaded map data

Use Verify Map Data if downloaded maps look incomplete, corrupted, or out of step with what you expected to see.

Verification checks the downloaded files on disk and reports the result when it finishes.