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HP PCs - Size of disk drive does not match specifications in Windows 10

HP computers with Windows preinstalled might appear to have a hard drive smaller than what is stated in the product specifications, documentation, or on the box.

Windows appears to report a smaller hard drive capacity because it shows information about one partition on the hard drive at a time and there are two commonly used reporting systems for binary data.

Understanding hard drive partitions and space usage in Windows 10

The number of hard drive partitions and their labels vary depending on the computer operating system.

HP computers with Windows 10 have hard drives that contain two partitions. The first partition contains space that is usable. This is usually the C: drive and might be labeled Local Disk, OS, or Windows.

The second partition contains system recovery information and might be labeled Recovery, Recovery Image, or HP_Recovery.


Some HP computers with Windows 10 have hard drives that contain a third partition labeled SYSTEM. This partition is protected space used by Windows. The information stored on the System partition is used to store important system files including startup recovery and system restore points.

Viewing total disk space in Windows 10

Use System Information to view the total size of the hard drive. System Information reports total space in both binary notation and in total bytes (decimal); you can use these measures to understand true disk space.

  1. To open the System Information window, search for msinfo and open System Information.

    Identifying the System Information window
  2. Under System Summary, click Components > Storage > Disks.

  3. View the provided information. For example, the following image shows total disk space and the two partitions on the hard disk drive. Total disk size is 596.17 GB (gigabytes) as reported by Windows, which equals just over 640 billion bytes in exact size when using decimal measurement. This is a typical 640 GB hard drive.

    Example hard disk drive space

    1. Total hard disk drive space

    2. Protected space used by Windows

    3. Space for normal use within an operating system

    4. Space reserved for a system recovery

Enabling unallocated space in Windows 10

Sometimes the total amount of disk space is not made available and a portion of the hard drive space is not allocated. This can happen if an additional hard drive is added and not partitioned correctly, or the factory-installed software image did not properly match the size of the hard drive.

If your hard drive contains a significant amount of unallocated space, use the following process to add the unused space to the hard drive.


Do not use the RECOVERY or FACTORY_IMAGE partition. Doing so allocates the unused space to the system recovery partition which is used only to recover the computer.


Do not use the SYSTEM partition. Windows uses this partition to store important system files including startup recovery and system restore points.

  1. To open the Computer Management window, right-click Start, and then select Computer Management. If you are prompted for an Administrator password or confirmation, type the password or provide confirmation.

    Identifying the Computer Management window
  2. In the left pane, select Disk Management. You can view the amount of unallocated space on the drive from the Computer Management window. Unallocated space appears in a section without a partition label and with a black bar at the top. Unallocated space is unused space on the hard drive that cannot be used.

    250 GB disk drive showing with 11.72 GB of unallocated space

    If unallocated space is not listed for a disk, the disk is correctly allocated.

  3. From the Computer Management screen, right-click the hard drive volume that you want to extend (for this example, Disk 0 (C:)), and then select Extend Volume. Do not select the SYSTEM, RECOVERY, or FACTORY_IMAGE partition.

    Extend Volume selected in the Computer Management window
  4. When the Extend Volume Wizard opens, click Next.

  5. Select the disk that you want to extend, set the amount of space to extend, and then click Next. To accept the maximum amount of available unallocated space, do not change any of the size values shown.

    Identifying the Extend Volume Wizard
  6. Click Finish. You can now use the previously unallocated space and the Computer Management window shows the correct values for the drive capacities.

    250 GB disk drive with fully allocated space

What is the difference between decimal and binary when measuring a hard drive size?

Different software and hardware and vendors use different methods for measuring a gigabyte. What Windows displays as the size of a hard drive might be less than the actual size.

Definition of decimal hard drive size

Hard drives are described and advertised by manufacturers in terms of decimal (or base 10) capacity. In decimal notation, one megabyte (MB) is equal to 1,000,000 bytes, and one gigabyte (GB) is equal to 1,000,000,000 bytes. The decimal system is what we are accustomed to in everyday life.

Definition of binary hard drive size

Windows and other programs have reporting features that use the binary (or base 2) numbering system. In the binary numbering system, one megabyte is equal to 1,048,576 bytes, and one gigabyte is equal to 1,073,741,824 bytes.

Converting binary hard drive size to decimal hard drive size

When determining hard drive capacity with software that reports in base 2 notation multiply the base 2 notation value by 1,048,576 to determine the decimal equivalent.

Why is there a Recovery or Factory Image partition?

The information stored on the Recovery or Factory Image partition is important system information that consists of a backup of Windows and original factory-installed software.

HP does not include recovery discs with most computers because of the following:

  • Discs can become destroyed by scratches.

  • Discs can become lost.

  • Discs can fail after prolonged exposure to sunlight.

  • Discs add cost to the price of the computer.

  • Recovering from the hard drive is substantially faster than recovering from discs, and does not require disc swapping.

You can still create recovery discs using the recovery software program provided by HP. For more information, see HP PCs - Obtaining PC Recovery USB Drives or Discs.