If you have a new SD card, using the tool SDFormatter makes sense.
However, if you are having a problem with an old SD card or USB drive, it also can help you.
I was trying to install Chrome OS on my SD drive and USB drives using tools unetbootin and win32diskimager. These tools would burn the files to the drive without difficulty. But later, when I wanted to use them, Windows 7 would only recognize 1 GB of space, despite them both being much bigger (4 GB and 8 GB). Typical Windows formatting didn’t help.
I tried SDFormatter on the SD drive first. That worked great. I decided to try it on the USB drive. That worked too! Very quick, and the drives were reformatted and restored to their proper size! Whew. I successfully tested putting a file on each one as well.
It’s a great little tool. I recommend it to help you deal with flash memory.