How to partition a drive in Windows 10 or 11

A separate drive letter can help organise files. If C: and D: are on the same physical disk, a failure can affect both. Save important files to a different drive or a cloud backup before changing partitions.

1. Find the correct drive in Disk Management

Right-click Start and open Disk Management. Check the disk number, total capacity and existing drive letters. Leave EFI and recovery partitions alone. If a drive that used to hold files appears unallocated or not initialised, stop and check its health or recovery options before writing to it.

2. Shrink an existing partition

Right-click the intended NTFS volume and choose Shrink Volume. Windows shows the amount it can shrink. Enter the space to set aside in MB and leave enough room for updates and applications. A paging file or other immovable files can limit the shrink size even when the volume has free space.

3. Create a volume in the unallocated space

Right-click the newly unallocated area and choose New Simple Volume. Choose a size, assign a drive letter such as D: if available, and format the new volume as NTFS for typical Windows use. Check the new letter and capacity in File Explorer.

4. Prepare a genuinely new SSD or HDD

If your new blank drive shows Not Initialized, right-click its disk label and initialise it as GPT for a modern system. Then create a simple volume. If the disk is already formatted and only lacks a letter, use Change Drive Letter and Paths instead.

5. Check before extending a partition later

Disk Management normally requires unallocated space directly after the volume on the same drive. Deleting a volume erases its files. Back up and verify the data before considering any deletion, and avoid changing the letter of the Windows volume.

References: Microsoft’s shrink-volume guide and extension requirements.