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Memory card for eTrex 20 – size and format?

Hello, all.

I am a new owner of an eTrex 20, which comes with an incredibly sparse (and unclear) user manual. I need a microSD memory card, but the manual gives me no clues about any size limitations or how it should be formatted (file system). Any tips?

If it matters, I’m on a Mac.



  • Boyd 1985 Points
    edited May 2015
    The answers are available by doing a search at :)

    I have used Macs as my primary computers ever since 1985, however I generally use my Windows machine for anything related to GPS and maps. Some people have reported problems with cards formatted on the Mac, although it seems pretty rare. Most likely, you will not need to format the card at all. Cards up to 32gb should be pre-formatted correctly.

    There isn't much reason to get a really big SD card unless you plan to use a large amount of BIrdseye imagery. There is a technical limitation to Garmin's map format related to segments (the smaller tiles inside a map). You will likely exceed this limit long before you are able to fill a 16gb card. If you exceed the segment limit, buggy things will happen and you will not be able to access all your maps.

    The exact number of segments that can be accessed varies by device, but it is approximately 4000. Mapinstall should show you the number of segments you are sending when you load maps.
  • SamuelD 12 Points
    Boyd said:

    The answers are available by doing a search at :)

    Ah, so they are. Thanks for pointing that out. Looks like half the stuff that should be in the manual is on that site. Good to know.
  • SamuelD 12 Points
    Got a 16 GB, Class 10, SanDisk microSD card for €8.90. I had no idea they had got that cheap! The shop didn’t even have 8 GB cards anymore.

    I then downloaded the “Routable Bicycle (Openfietsmap Lite)” map for France (as a gmapsupp.img file – not actually a disk image!) from here (thanks to DaveM in another thread). I then created a root folder called GARMIN on the memory card and dumped the file in it (didn’t format the card).

    And wonder of wonders, it worked first time! I am astonished. Very cool. Remains to be seen whether I like the map, of course.
  • sussamb 813 Points
    If you don't there are other maps out there.
  • DaveM 159 Points
    On a card that size you can have more than one map.

    I use the Openfietsmap on my bike and an OSM topo for hiking. You can have different maps enabled and disabled in different profiles. That way when you switch profiles you don't need to change the map settings.

    If you use your eTrex for more than one thing it would be worth setting up a profile for each use.
  • sussamb 813 Points
    Agreed, that's what I do also.
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