This walk-through 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 Windows or Mac reports, in the properties window of their drive, less capacity than their drive seemed to advertise. A drive advertised to contain 500 GB displays as 465 GB, a 1 TB drive displays as 909 GB, or a 1.5 TB drive displays as 1363 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