If it's anything like a hard drive, which I'm 95% sure it is, then it's all the in the way they define a gigabyte...
It's not right in terms of how a computer will define it, but manufacturers define 1 GB as 1000000000 bytes instead of 1073741824 bytes.
So 16GB to them means 14.8 ish GB in reality.
Happens with all pen drives and hard drives, etc. Take a look next time if you weren't aware of it, but hard drives are always much smaller than they logically should be.
So I guess 32GB would actually show up around the 29GB mark.
According to some manufacturers 16 Giga bytes is 16 Billion bytes (10^6), but in computer terms a Kilo Byte is 1024 Bytes , not 1000 Bytes, similarly a Mega Byte is 1024 KiloBytes and a Gigabyte is 1024 MegaBytes.
To convert 16Billion bytes : 16 x 1000^3 to actual Gigabytes, you have to divide by 1024 ^3, then you get 14.9GBs.
The FAT (File allocation table) also takes up some space around 4 bytes per every 4KB block if I'm not mistaken. Given everything you should see something slightly less than 14.9 GBs. On mine it reads 14.83GB, which sounds right.
I have just copied this i was reading up on it a while back when i was looking for the same reason as you. It just tells me the card was ok. Didn't understand any of it tbh.
Edited by rover644 (22nd Jul 2014 5:40pm)