How to merge unallocated space in windows 10

Diskpart is a command-line utility built into Windows that can also merge unallocated space in Windows 10 for free.

Press Win + R, type cmd, then right-click and run as administrator.

Type diskpart and press Enter.

diskpart

Type the following command to show all volumes on your system (C:, D:, etc.), each with a corresponding number.

list volume

Identify the volume you want to extend (e.g., C: drive). Then type:

select volume x

Replace X with the volume number of the target partition. For example:

If there is unallocated space directly after the selected volume, type:

extend

This will merge all the adjacent unallocated space into the selected volume.

⚠️ Important Notes:

1. Diskpart only works if the unallocated space is immediately after the selected volume.
2. If the unallocated space is not adjacent (e.g., before the volume or between other partitions), Diskpart won’t work—you’ll need third-party software.