How to downsize a 4GB compact flash card to 2gb

For the non supperted camera flash disk resize

How to downsize a 4GB compact flash card to 2gb

tags: 2gb, 4gb, camera, compact flash, compactflash, diskpart, fat,file, format, hardware, legacy, limit, partition size, reduce file size,tetracam


I recently had to put a new CF card in an older infrared camera for one of our field sites. Unfortunately the camera only supports up to 2GB sized CompactFlash cards but local retailers only carry 4GB cards these days and I didn’t have time to order one online. After a few hours of online research and trial and error, I finally figured out how to do it using the windows “diskpart” utility. This hack will only work in in Vista and Win7 because diskpart in XP won’t recognize the card.




[Note that in the example below, things in italics are commands you type.]
Before starting, please remember that you can seriously mess things up if you make a mistake using command line disk management. Please make 150% sure you are selecting the correct disk so you don’t format your hard drive. You are solely responsible for anything that happens as a result of using this code :)

Instructions for reducing the partition size of a compact flash (CF) card:

Open a command Window (Windows-> Start -> cmd)

Type diskpart A new window will open up with a “diskpart” prompt

list disk

select disk n (where n is the number of your CF card)

list volume

select volume n (where n is the number of CF card volume)

clean all (this completely reformats the disk – it will take a while and appear to hang but be patient)

create partition primary (this gives the newly formated CF card a partition so it can be resized)

shrink querymax This will tell you how much space is currently on available on your CF card. Subtract this from the filesize in MB you want for the final disk than add 1.

For my 4GB disk, shrink querymax returns:

“The maximum number of reclaimable bytes is: 3824MB”I wanted a final disk size of 2GB which a google search told me is 1954MB so 3824 – 1954 + 1= 1871

shrink desired = 1871 (This tells diskpart to try and shrink the disk by 1871 MB)

Now that the disk is the right size, you can format the partition…

format fs=fat label=”volumelabel”


That’s all it takes.
More info on diskpart commands here:
http://technet.microsoft.com/en-us/library/cc766465(WS.10).aspx