Knowing the exact size of the hard drive is crucial because you need to know how much data can possibly be stored to the drive.
1. Click on the drive that you wish to find out the size on the left side of the software.
2. Select the “Information” utility (this is located in the “Clean Up” area tools area).
3. Text detailing all the information on the drive will appear, to look for the exact size, look for “Size:” (the third one from the top). This will show you the exact size in both gigabytes and bytes.