Better technology allows manufacturers to build smaller PCs, and most machines only need one large-storage capacity hard drive. Further, a Windows PC might have multiple partitions of varying sizes on these drives. The "C" partition usually holds the operating system, programs and data files. Partition letters that follow might hold a recovery partition or they might serve as a backup location. If you run out of space on a partition, such as the all-important "C" drive, certain computer functions might become unusable. If this is your predicament, Windows can repartition drives and increase space for any particular drive.
Shrink One Drive
Click "Start." Type "Computer Management" in the search box at the bottom of the "Start" menu. Press "Enter" to open the Computer Management console. Click "Disk Management" under "Storage" in the left pane.
Right-click on the drive letter, such as "C" or "D," that you are reducing in size. Select "Shrink Volume" from the menu.
Click the down arrow or manually type in the number of megabytes (MB) that you want to remove from the partition, next to "Enter the Amount of Space to Shrink in MB." The maximum amount of space you can take from the drive is listed next to "Size of Available Shrink Space in MB."
Click the "Shrink" button. Wait for Windows to automatically remove the space from the partition. You will see a dialog box on the screen indicating the progress of the shrinking process. After Windows has finished, you might see that removed space in a neon-green partition labeled as "Free Space." That free space will not have a drive letter, such as "C" or "D."
Extend Another Drive
Open the Computer Management console.
Right-click on the drive letter that you want to expand in size using the free space taken from the previous drive. Select "Extend Volume" from the menu.
Click "Next" in the "Extend Volume Wizard" dialog box. Find the amount of available free space next to "Maximum Available Space in MB."
Find the box next to "Select the Amount of Space in MB." Type in a reduced number to save free space for other drives or leave the number as is to use all of it for the selected drive.
Click "Next." Wait for Windows to automatically add free space to the selected drive. Bring the Computer Management window back up after the process is complete. Verify that the selected drive has increased in size.
The terms "drive," "partition" and "volume" are used interchangeably.
Administrator privileges are required to change partitions.
Avoid removing all of the free disk space from the primary partition, usually the "C" drive. This partition holds the Windows operating system and installed third-party programs. Most importantly, when you create files and save them to the hard drive, the OS and other applications direct your files to the "C" drive by default.