This walkthrough will cover capacity limitations for external (USB, Firewire and eSATA) drives, Serial ATA (SATA) drives and Parallel ATA (IDE) drives.

One type of perceived capacity limitation applies to all types of hard drives. Often hard drive users notice that both Windows and Mac, in the properties window of their drive, report less capacity than their drive seemed to advertise. A drive advertised as containing 500 GB displays as 465 GB, a 1-TB drive displays as 909 GB, or a 1.5-TB drive displays as 1,363 GB. What happened to the rest of the drive's advertised capacity?

For more information on drive capacity issues, please see this Seagate Knowledge Base article:

Why does my drive display less capacity than advertised?

No other capacity limitation applies to external drives.

For more information on Serial ATA Drive capacity limitations, please see this article:

Serial ATA Drive Capacity Limitations

For PATA (IDE) drives:

Choose the size limitation you are seeing for instructions on how to recover the full drive capacity:

• 127 GB to 137 GB
• Drive capacity minus 68 GB (while using Windows FDISK, such as an 80-GB drive seen as 10 GB)
• 32 GB to 33.8 GB
• 8.4 GB
• 4 GB
• 2 GB