So I know most SSD's are 2.5" and I recently bought a Dell Inspiron 14" 7000 Series laptop and in this video the guy that installs a Samsung 840 Pro SSD in it says that it bumps out a little and that the SSD is an additional 2mm thicker than the hard drive that was in the system.
1. Check if your computer has an mSATA connection for an mSATA ssd. Some of the high end versions of your model come with an mSATA connection. Budget models did not come with an mSATA connection.
2. Check with Dell to find out if they have an OEM version of the Samsung drive that will fit your model. Samsung has numerous contracts with computer companies to supply OEM versions. Samsung has a contract with Dell. The Dell versions have different model numbers, product numbers, and SKU's.
3. The Samsung 840 Pro ssd is 7mm thick. That is the standard thickness for a SATA 3 6Gb/s ssd. It should fit in laptops, notebooks, netbooks, and some ultrabooks. Samsung makes 840 Pro ssd's specifically for mobile computers. The model numbers of the retail versions are:
250 GB: MZ-7TE250LW
500 GB: MZ-7TE500LW
Model numbers for OEM versions will be different. Model numbers may be different outside the USA. Just look for the netbook upgrade version.
BTW - The 2.5 inches refers to the width of a standard SATA 3 6Gb/s ssd. The mSATA ssd's and the new M.2 NGFF ssd's are much narrower, shorter, and do not come in an enclosure. In fact they are tiny when compared to standard ssd's.