In Windows, “merging” a partition with unallocated space usually means extending the existing volume into that space. Disk Management can do this only when the unallocated area is immediately to the right of the target, on the same disk, and the target uses NTFS or ReFS. If another partition is in between, the built-in tool cannot extend across it.
Before deleting, moving, or resizing anything, inspect the disk map and identify each partition. The steps below cover the straightforward case first, then what to do when the space is not adjacent.
Check the disk layout before changing partitions
Unallocated space is disk space that does not currently belong to a formatted volume. It is different from unused capacity inside a volume, which is already assigned to a partition. To see the layout, open Disk Management by right-clicking Start and selecting Disk Management, or run diskmgmt.msc as an administrator. Unallocated space appears with a black bar and the label Unallocated. Microsoft’s Disk Management overview covers Windows 10 and 11: Microsoft Support: Create and format a hard disk partition.
- Confirm the target volume and the unallocated space are on the same physical disk.
- Check that the unallocated space is immediately to the right of the target in the disk map.
- Confirm that the target volume uses NTFS or ReFS.
- Identify any partition between the target and the free space, and determine whether it contains data or serves a system or recovery role.
Microsoft’s extension procedure applies to Windows 10, Windows 11, and Windows Server 2016, 2019, 2022, and 2025; the documentation was last updated June 11, 2025. It specifies that unallocated space must be immediately after the volume being extended: Microsoft Learn: Extend a basic volume.
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Extend a volume when the unallocated space is adjacent
Use Disk Management
- In Disk Management, right-click the volume you want to enlarge and select Extend Volume.
- Follow the Extend Volume Wizard. Choose how much of the available unallocated space to add; the wizard defaults to all available space, but you can enter a smaller amount.
- Review the selection and finish the wizard. Check the disk map to confirm the volume now includes the space.
If Extend Volume is unavailable, recheck the same-disk, adjacency, and filesystem requirements before making any changes.
Use PowerShell as an administrator
Microsoft also documents extending a partition with PowerShell. Replace C with the drive letter you intend to resize, and review the disk layout before running the commands:
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- Open PowerShell as an administrator.
- Get the maximum supported size for the target partition:
$size = Get-PartitionSupportedSize -DriveLetter C - Resize the partition to that maximum:
Resize-Partition -DriveLetter C -Size $size.SizeMax
The second command uses the largest supported size returned by the first. If you want to add less than the maximum, specify an appropriate size rather than using $size.SizeMax.
Choose a path when another partition is in the way
Disk Management cannot extend a volume across an intervening partition. The practical choices are to leave the space separate, remove the intervening volume after protecting its contents, or use a partitioning tool that can move volumes.
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| Option | When it fits | Main trade-off |
|---|---|---|
| Keep the unallocated space separate and create a new volume | You want to use the space but do not need to add it to the existing volume. | The space becomes a separate drive volume rather than enlarging the target. |
| Back up and delete the intervening volume | The partition is expendable, and its files have been backed up or moved. | Deleting a volume deletes its files. Do not assume a recovery or EFI partition can safely be removed on every computer. |
| Move a partition with a capable partitioning application | You need to preserve the intervening partition and the tool supports the disk’s layout. | Moving boundaries is higher risk, can take time, and may make an operating system fail to boot. |
Moving a partition is layout-dependent
A partition tool such as GParted can, depending on the layout, shrink a partition, move its boundary, and then grow the target into newly adjacent unallocated space. The free space still has to end up immediately beside the volume being grown. Logical partitions inside an extended partition have additional boundary constraints, so there is no safe one-size-fits-all sequence for every disk, particularly one containing system, EFI, or recovery partitions. GParted’s hosted moving-space explanation is a sample chapter from Manage Partitions with GParted How-to, not a complete current manual: GParted: Moving Space Between Partitions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Back up and account for compatibility before resizing
- Back up important files before moving a partition boundary. GParted characterizes moving a partition as high-risk and warns that it may cause an operating system not to boot.
- After moving or resizing a partition containing NTFS, boot into Windows twice. GParted advises doing so so Windows can perform filesystem consistency checks.
- Use GPT if a disk larger than 2 TB needs to use more than 2 TB. Microsoft identifies GPT as the requirement for using capacity beyond 2 TB on such a disk.
- Do not format a volume to solve an extension problem. Formatting destroys the data on that partition; Microsoft advises backing up before formatting.
These general procedures cannot identify which partition is safe to move or delete on a particular PC. If the intervening partition’s purpose or contents are unclear, do not remove it as a shortcut.
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