How to shrink c drive without losing data on Windows 11?

You can use the diskpart system utility to shrink c drive to d drive without losing data. This is for both Windows 11 and Windows 10.

Important Notes:

Backup First: Always back up critical data before modifying partitions.

Adjacent Space Required: D: must be immediately after C: on the disk layout for this to work. If partitions are not adjacent, you'll need third-party disk partition tools to move partitions.

Unallocated Space: Shrinking C: creates unallocated space after it. To extend D:, this space must be directly before D:.

How to shrink c drive to d drive on Windows 11/10

Press Win + X > Disk Management. Verify that D: is adjacent and to the right of C:.

Press Win + S, type cmd, right-click Command Prompt > Run as administrator.

Run DiskPart:

diskpart
list disk                 > Identify your system disk (e.g., Disk 0)
select disk 0             > Replace "0" with your disk number
list partition            > Note C: and D: partition numbers
select partition 1        > Replace "1" with C:'s partition number
shrink desired=10240      > Shrink by 10GB (replace "10240" with your size in MB)
list partition            > Confirm unallocated space appears after C:
exit

Extend d drive to the new unallocated space:

diskpart
select disk 0
select partition 2       > Replace "2" with D:'s partition number
extend                   > Absorbs the unallocated space
exit

Open Disk Management or run diskmgmt.msc. Confirm D: size increased and C: decreased.