To add the handy tid bit
@RumoredNow has said, when the a blank storage medium is formatted with a file system it has the specified amount of space but space is lost due to creation of the file system. Some are more efficienct than others but you still lose space.
As result most devices that ship with 32 Gigs of storage actually have 28 Gigs of storage.
So what this means in this case that Dell have specified how much data the storage medium can technically hold not that amount that is accessible. In terms of legality it means there is no false representation of information.
If you are wondering why space is lost:
To put it simply, imagine a file system is table of rows and columns if you increase the thickness of the borders of all the rows and columns you will have less space in the cells for data. Therefore some file systems have less thicker boundaries. So therefore in Mechanical hard drivers files are store in parts of each cell, a group of cells makes up a cluster. Hence why if you have a combination of larges files and smaller files, the latter being more prevalent you will end up with a fragmented drives ergo why everyone experiences a system slow down (along with other factors) after a while with a new PC or Laptop running a mechnical drive. As the files are spread over different cells and clusters, the further apart they are (fragmentation) the longer it takes for the O/S to pieces together to load the file. (The best application I've come across that resembles this behaviour is Disktrix - Ultimate defrag. As the UX is not a grid or block but representative of a HDD platter).
Imagine a jigsaw puzzle with all the pieces scattered all over the table, if the pieces you need are grouped together - then it's quicker for to find the pieces and place them. Therefore further apart they are then the longer it will take to piece everything together.
In regards to SSDs, you will always have space lost due to over provisioning - this is a requirment to reduce the read and write cycles thus prolonging the life of the SSD. In simple terms, the data is stored in chunks or blocks so the files are intact not spread over cells or clusters. So no defragmentating of SSDs is needed. It's a big november golf - that you should not defrag SSDs as that drastically reduces the life of an SSD.
I hope this clarifies any confusion caused why you don't really get the space advertised in a storage device (unless you compress the entire partition but that's another topic and thread).