Garmin Nuvi 660

Hi Guys.

What a great site this is btw, Many thanks:)

Ok for anyone who has an older Garmin ie one of the nuvi 660 range, I found that placing the maps on a sd card seems to have a limit of around 2GB, So for example any combination of maps or Germany does not show, so keeping the map below this limit should work perfectly.
Another add on is downloading POI points speed cams etc on to the same SD card to go along with the map (using the garmin poi loader), is another good point, again with this Garmin model it seems to have some sort of limit which I found to be around 19 or 20 POi points, with each SD card you can change the country and add the POi to that country with it.

But if anyone has another experience with this model and maybe I’m not doing something right and could do better, then let me know, I’m an older guy and all this computer stuff is not my forte, much prefer a hammer.

c’est la vie.


You’ll get better response on the Garmin forum on this board.

I also have limited computer experience (about a half century) and understand the feeling of if all you have is a hammer, then everything looks like a nail.

Garmin forum.
Garmin advice on SD formating.
Garmin’s official statement on SD card sizes.
Garmin receivers do not understand exFAT. FAT16 or FAT32 must be used. If SD card is larger than 32GiB, then the operating system, by default, will format the the SD card as exFAT, which the Garmin receiver does not understand.
Here is a formatter that will format a large SD card as FAT32
Per Wikipedia, FAT16 is limited to a 2GiB partition(volume) size unless 64KiB cluster size is used, which is not a default formatter setting.
The file size limit is the same as the partition size under the same conditions.
Per Wikipedia, FAT32 is limited to a 2TiB partition(volume) size, which is larger than any extant (August 2018) SD card.
The file size limit is 4GiB.

I have noticed that Garmin receivers seem to have a limitation on both file size and partition and volume size that they must be strictly less than the implementation limit by at least a byte.

GiB is 1024^3 bytes. GB is 1000^3 bytes.

I have learned that Garmin receivers only use the first partition of a SD card, which must be a primary partition. I use SD cards up to 64GiB in may receivers by using Control Panel ==> Administrative Tools ==> Computer Management ==> Disk Management to delete the original partition from the SD card and then first creating a slightly less than 2GiB partition for the receiver to use and make the remainder of the SD card into an operating system native format partition in which I can hold other support files. This permits me to have swappable map images that can be copied by a small laptop to the first partition. With MapSource on my laptop, that means I can make new map selections away from home.

Just noticed this section, So apologies for doing it twice, thanks


Thanks for that info.

So please bare with me on this, So what you are saying is that “Some” Garmin’s have this limit of around 2GB for one file, on a SD card?

I also add other info, like poi points and pictures and music etc, which the Garmin reads ok, its just the map that is over 2 GB that is not picked up.

I take it you add the additional map outside the Garmin file on the SD card?, then swap it when needed, for example I have had to split Germany to north and south around 1GB each, so both can sit on the SD card and with the aid of a computer can be changed when needed, is that correct?

I have had Garmin receivers from over the last 25 years. Some are not mapping receivers. Of those that are mapping receivers, some have a FAT implementation that does not support using 64KiB clusters. 64KiB clusters is the only way to reach 4GiB files (and therefore, maps). Hence the use of the word “some”.

Remember, a Garmin map (gsuppmap.img) is a single file and is limited in size by the file size limit. Also, older receivers have a limit on the number of tiles in a map, for example, 1024 or 2025.

The file size limit is on the size of individual files. The number of files permitted is actually quite large and seldom is a problem.

The SD card may have multiple partitions (in Windows terminology, volumes, each with its own disk letter (for example, K:)). That is what my last paragraph was about in my previous posting.

I suggest following the links in my previous posting and reading the associated articles.

A SD card can be partitioned like a hard drive.

I have made and use Garmin MapSource mapsets larger than 10GiB, which can not be written to a FAT32 partition as they are too large. When using a 64GiB SD in a Garmin receiver that uses a SD card, I divide the card into 2 partitions: a first partition slightly less than 4GiB for maps and other data for the receiver and the remainder of the space I make a large NTFS formatted partition for my large MapSource mapsets (the Americas, Oceania, Asia, Africa and Europe).


Many thanks for your reply, I think you are a lot smarter than me, I have learned something new today. thank you.

I’m sort of thinking for my level, just having a few cheap SD cards with a limit of 2GB is perfect for me (I have four anyway to hand) I can label them with the country, plus add around 18 poi points relevant to that country, plus any interesting pictures again relevant to that country…

Simply changing the SD card when entering the country, will give me everything I need. as I often take my computer with me so any new files can be quickly added or taken away., But with a little planning 4 SD cards is more than enough for me personally., How often do we travel to more than four countries in a day., Anyway again with planning this great site will provide an custom made map to cover many countries and keeping the limit down to 2GB.

Thank you again with explaining what you have done and showing me some new things.