Need help in upgrading HDD

Any standard 2.5" will fit. Very easy to do...go to ifixit.com if you don't know how.

Purchase a 2.5 external housing for the old one if you want to migrate your stuff (and also make use of the old drive afterwards). Newegg is good for those.

 

Im upgrading to an ssd in my 2009 macbook, and i used these websites to buy it, they also have hdd and show which ones are compatible with macs, google crucial and, then google macsales and compare the prices, hope this helps

 

Unless you're using a laptop like the rMBP, or a desktop workstation, most computers made in the last few years use 2.5" SATA connection. I think it kind of hard to find a hard drive that isn't 2.5" for a laptop.