How to Repartition a Disk Drive in Windows - dummies

How to Repartition a Disk Drive in Windows

By Dan Gookin

The art of repartitioning involves several steps in Windows. The drive must first be shrunk. Windows uses any free space on the drive to create a new, unallocated partition. The second step is to allocate that partition, creating a new volume, using the space made available by shrinking the drive.

To shrink a volume, follow these steps:

  1. Clean up the drive.

    Remove unused files. Empty the Recycle Bin. Perform other actions to ensure that you’re not wasting space on the drive.

  2. Open the Disk Management console.

    1. Open the Control Panel.

    2. Open the Administrative Tools window.

      In Windows 7, choose System and Security and then Administrative Tools.

      In Windows Vista, choose System and Maintenance and then Administrative Tools.

      In Windows XP, open the Administrative Tools icon.

    3. Open the Computer Management icon.

      In Vista, click Continue or type the administrator’s password.


    4. Choose Disk Management.

  3. Right-click a volume.

    It cannot be the system volume, such as drive C, or a media card, a flash drive, or an optical drive. It must be a hard drive.

  4. Choose Shrink Volume from the shortcut menu.

    Windows displays the Shrink dialog box where you can set the size of the new partition.


  5. Set the amount of disk space to release.

    Use the text box by the item Enter the Amount of Space to Shrink in MB to set the new volume size. The amount listed is 18,387MB, or just over 18GB of storage. That’s also the maximum amount that can be shrunk; you can set the value lower, but not higher.

  6. Click the Shrink button.

    When the operation has been completed, you see the new unallocated volume appear in the same slot as the current drive in the Disk Management console.


After shrinking an existing volume, a new volume has been created. Because the volume is unallocated, it’s not available for use.

To allocate the unallocated space as a usable hard drive in Windows, follow these steps:

  1. From the Disk Management console, right-click the unallocated volume.

  2. Choose New Simple Volume from the shortcut menu.

    The New Simple Volume Wizard appears.

  3. Click the Next button.

  4. Set the size of the new volume by using the Simple Volume Size in MB text box.

    The size is already preset to equal the entire disk capacity, which is recommended. If you set it to a smaller size, the remaining space on the drive continues to be unallocated.

  5. Click the Next button.

    You can assign the drive a letter or mount the drive as a folder. Or, you can do neither, depending on how you fill in the wizard.

  6. (Optional) Choose a letter for the new volume.

  7. Click the Next button.

  8. Ensure the option Format This Volume with the Following Settings is chosen.

  9. Ensure that the NTFS format is chosen.

  10. Click the Next button.

  11. Click the Finish button to create the new volume.

    The amount of time taken to complete the operation depends on the size of the volume. Larger disk drives take longer.

    The display in the Disk Management console shows the drive being formatted; you can watch its progress in the Status column at the top center of the window. The drive isn’t assigned its new letter until after it’s formatted.

  12. When the operation is complete, you can close the Disk Management console.

The newly created disk drive appears in the Computer window. It’s immediately available for use.