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Extend Volume greyed out – Fix

There is unallocated space on the system, but it’s impossible to extend the volume in Disk Management. The Extend Volume option is greyed out. How to quickly fix Extend Volume on the system and go on with other tasks? In this article, we will look at how to extend volume on the (C:) drive.

Extend volume greyed out in Disk Manager

You did add space to the Windows system and want to extend the volume. Unfortunately, in Disk Management, the Extend Volume is greyed out.

In this example, we like to extend the (C:) volume with 8.00 GB of unallocated space.

Extend Volume greyed out download FREE software DiskGenius

Fix extend volume greyed out

We need a FREE tool that extends the (C:) drive with unallocated space. Is there a tool we don’t have to pay for that is easy to use? Yes, there is.

We will use the software DiskGenius to extend the volume on (C:) drive. Download the tool from the official website or here (direct). Next, install it on the system.

The version we will use is DiskGenius DGEngSetup5431342.

Extend Volume greyed out Disk Management

Extend volume greyed out (C:) drive

Go through the below steps to extend the volume:

Start DiskGenius.

Extend Volume greyed out DiskGenius

Right-click on Free > Select from menu Allocate Free Space To > Select from submenu Partition: Local Disk(C:).

Extend Volume greyed out allocate free space to

Click Yes.

Resize warning

Click OK.

Reboot computer warning

The Windows system will reboot, and DiskGenius will start in Preinstallation Environment (also known as Windows PE and WinPE).

Note: DiskGenius will automatically start in Windows PE after a reboot. Go through the steps, and reboot the system.

Extend Volume greyed out volume Windows PE

Windows system is back up. Let’s start Disk Management and check the (C:) volume.

Extend Volume greyed out volume extended

Everything looks great!

Did this help you to extend the volume in Windows?

Read more: Secure wipe hard drive and solid state drive in Windows »


You learned how to extend volume when it’s greyed out in Disk Management. Use the DiskGenius software to extend the volume on (C:) drive or any other drive when Disk Management does not let you do that. It will take a couple of clicks, and you’re all set. The best of all, it’s FREE.

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ALI TAJRAN is a passionate IT Architect, IT Consultant, and Microsoft Certified Trainer. He started Information Technology at a very young age, and his goal is to teach and inspire others. Read more »

This Post Has 2 Comments

  1. Hey Ali, Needed to extend space on W2016 Server Std Virtual Machine ,host ESXi 6.5.
    Extend scenario as above,and Disk Genius (v5.4.3) process all went as above,however after the Win-PE reboot,the VM was inaccessible.

    -In Bios CDROM was the first boot
    -Could not see drives in BIOS

    Tried to convert usb boot disk genius to iso,unsuccessful- (cant boot esxi vm from usb)
    {Using disk genius it may have been possible to use recover partition option to resolve:convert usb-to-iso using usb image tool}
    Boot using parted magic showed the entire extend size as unallocated.
    Looks like the extend did not complete properly,any thoughts?
    Had to restore from backup to resolve

    1. Hi Moosa,

      Glad you were able to get the VM back up and running from the backup.

      I followed the exact steps in the article, and it worked as a charm. It never happened to me before, and DiskGenius is my go-to software for such tasks.

      – Windows Server 2019
      – VMware ESXi 6.7
      – Disk Genius

      It’s difficult to tell why this happens on your end. Perhaps you can send a message to the DiskGenius support team. They are always happy to help (even if you use the free version).

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