How to add unused space to c drive without formatting for Windows 11?

Adding unallocated ( "unused" ) space to your C: drive is straightforward as long as the free space sits on the same physical disk. Below are three no-cost methods that work on Windows 10 and 11. Back up important data first—partition changes are usually safe but never 100 % risk-free.

Partition Assistant Standard can move partitions as well as resize them. Here is how to add unallocated space to c drive on Windows 11 or Windows 10.

1. Right-click C: ▸ Resize/Move Partition.

2. If the unallocated space is not next to C:, first drag the entire neighbour partition left/right to make the free block contiguous, click OK.

3. Drag the C: partition’s right border into the unallocated space → OK ▸ Apply ▸ Proceed.

4. The program may reboot to PreOS mode; let it finish. This will add more space to c drive and increase the size of c drive dramatically.

Partition Assistant Standard can merge non-contiguous blocks, work on FAT32 data drives, and offer one-click Extend Partition wizards—all without data loss. Always download directly from the vendor and uncheck bundle offers during setup.

Final tips for adding unused space to c drive

1. Make a fresh backup or system image first.
2. Suspend BitLocker (if enabled) before resizing to avoid a recovery-key prompt on reboot.
3. After extending, run chkdsk /scan to verify the file system and defrag /K (or Optimize Drives) to tidy up.