Solution - can't extend C drive in Windows 7

Updated on: November 16, 2019

This article introduces why cannot extend C drive in Windows 7 Disk Management and what to do when unable to extend system partition C.

Why unable to extend C drive in Windows 7

Better than previous version, Windows 7 has new Shrink and Extend Volume functions built in Disk Management, which is able to change partition size without losing data. However, many people feedback that they can't extend C drive in Windows 7 Disk Management. Because after shrinking drive D, Extend Volume is disabled for C drive. This article explains why you unable to extend C drive with Disk Management and how to solve this problem with ease.

From Microsoft explanation, both Shrink Volume and Extend Volume functions only support NTFS partition. However, few computers use FAT32 partition for system C drive, so this is not an issue. There are other 2 common reasons why you can't extend C drive in Windows 7 Disk Management.

1. No adjacent Unallocated space

A 160GB hard disk cannot be increased to 250GB (except virtual disk), so before extending a drive you must shrink or delete another one to get Unallocated space. If you right click C drive directly, of course Extend Volume is greyed out.

By shrinking a volume, all files keep intact, so it is better than deleting. However, you can't extend C: drive by shrinking D via Disk Management.

Extend Volume disabled

This is because:

  • Shrink Volume function can only make Unallocated space on the right side while shrinking any partition.
  • Extend Volume function can only combine Unallocated space to the contiguous partition on the left.

As the screen shot shows, Disk Management cannot extend volume C: and E: after shrinking D.

In this case, you need to run NIUBI Partition Editor to move Unallocated space from right of D drive to the left, then C drive can be extended by either tool easily.

2. Restriction between Primary and Logical partition

Different with Windows 10 that formats disk as GPT by default, Windows 7 format the hard disk as MBR, so there is potential issue if you use the default MBR style disk.  One of them is that there are only 4 entries in Master Boot Record, (from which Operating System can easily locate the position of each drive), so you can only create maximum 4 Primary partitions or 3 plus an Extended partition.

Cannot extend partition C by shrinking D, some people try to delete it instead, but Extend Volume is still disabled after deleting, as the screenshot show.

Cannot extend

Unlike Primary partition that works as independently, Logical drives are part of the Extended partition, so disk space shows as Free instead of Unallocated after deleting.

In this situation, if you want to enable Extend Volume for C drive partition, you must delete all other Logical drives and then delete the entire Extended partition. Obviously, it's a bad way.

To NIUBI Partition Editor, there is no difference while shrinking and extending Primary and Logical partitions. You just need to drag and drop on the disk map.

Solution when you can't extend C drive with Disk Management

When you unable to extend C drive in Windows 7 Disk Management, run NIUBI Partition Editor, as the safest and fastest Windows partition software, it helps you fix this issue safely and easily. Comparing with Disk Management, NIUBI has more advantages while resizing disk partition such as:.

Move Unallocated space next to C drive

If you have shrunk the right contiguous partition D (or E), you must move the generated Unallocated space to the left side. After that, Extend volume will be enabled.

NIUBI Partition Editor

How to fix the common issue that can't extend C drive in Windows 7 DM:

Step 1: right click drive D: and select "Resize/Move Volume", drag middle towards right in the pop-up window.

Move Unallocated

Then Unallocated space is moved next to C drive.

Unallocated moved

Step 2: right click C: drive and select "Resize/Move Volume" again, drag right border towards right in the pop-up window.

Add Unallocated

Then Unallocated space is added into system C drive.

Unallocated added

Step 3: click Apply on top left to execute. (All operations before this step only work in virtual mode.)

If you deleted the right adjacent partition D, just follow STEP 2 to add Unallocated space to C drive.

Video guide

Video guide

Besides shrinking, moving and extending partitions, NIUBI Partition Editor helps you do many other operations.