If you are planning to buy a SSD for your laptop you will have many choices in brands and models. One of the choices you have to made is choosing the right size. SSD’s come in different storage capacities. The most common capacities are:

60GB and 64GB
120GB and 128GB
250GB and 256GB
500GB and 512GB
750GB
960GB and 1TB

How do you know which size you need? In order to find out which size is right for you, you can look up at your current usage. In Windows you go to My Computer and below the drive icons you’ll see the storage usage of your drives or partitions. For the best performance we recommend to let 1/5 part of the drive unused. That means if you buy a 120GB drive it should actually be 96GB. Below you’ll find an overview of what the actual (recommended) storage capacity is that you should use.

60GB and 64GB -> 48GB and 51.2GB
120GB and 128GB -> 96GB and 102.4GB
250GB and 256GB -> 200GB and 204.8GB
500GB and 512GB -> 400GB and 409.6GB
750GB -> 600GB
960GB and 1TB -> 768GB and 800GB

Or are you buying a new laptop? You can also take a look at the system requirements for the most common operating systems. For Windows 7 and Windows 8 you’ll need at least 20GB storage free, however with the amount of updates you’ll might need to have 30GB free on your drive.
For OS X10.9 Mavericks you’ll need at least eight GB free and witht the updates we recommended 12GB

Movies and especially HD TV series/epsiodes will eat up a lot of GB very easily. Compare to PC games and programs, you’ll store these faster and more often. However if you don’t watch a lot of series or movies but you do play PC games, then 120GB or 250GB is most likely to be sufficient for your storage needs.

Below you’ll find an overview of how many storage is left after installing the OS.