How to Extend VirtualBox Disk in Windows – Resize VirtualBox Disk

If the VirtualBox disk is filling up, you can resize and extend it. Here’re the steps to follow to extend the VirtualBox disk in Windows 10.

VirtualBox lets you create a disk of any size while creating the virtual machine. Depending on the operating system VirtualBox can also suggest the appropriate amount of disk space. For example, if you are installing Windows 10 in VirtualBox, you get 50GB as the suggestion for disk space. If you want to, you can customize the disk space using the slider.

After installing the guest OS, if the initial disk space is not enough, you can resize the virtual disk in VirtualBox. All you have to do is use the Resize option in the VDI properties. In this quick guide, let me show you the steps to extend the VirtualBox disk size.

Important Note: Before following the steps, make sure the virtual machine is turned off. That is, not in a saved state. If it is in a saved state, resume the VM and shut down the OS.

Steps to Extend Disk Size in VirtualBox

You can extend VirtualBox disk size from the Virtual Media Manager tool. Here are the steps to do so in Windows.

1. Open VirtualBox.
2. Click “File” and select the “Virtual Media Manager” option.
   
3. Select the virtual disk (VDI) you want to expand.
   
4. Use the slider next to “Size” to resize or expand the disk. You can also enter the exact size in GBs in the field next to the slider.
   
5. Click “Apply“.
6. Close Virtual Media Manager.

As soon as you apply the changes, the VirtualBox disk will be resized according to the settings. For example, in my case, the disk has been resized from 35GB to 45GB.

Do keep in mind that the newly expanded space will be shown as unallocated space in the guest operating system. You need to manually partition the unallocated disk space in the virtual OS. You can use the build Disk Management tool in Windows to create, extend, or resize partitions.

Command to Resize VirtualBox Disk Size

You can use the VBoxManage command to resize the VirtualBox disk. Here’s how.

1. Open Start.
2. Type “CMD” and press Enter.
3. Enter cd "C:\Program Files\Oracle\VirtualBox" in the command window and press Enter.
4. Now, execute the below command. Replace “<absolute path to file>” with the actual full path of VDI file along with its extension and “<size in MB>” with the new disk size in MegaBytes (MB).
   VBoxManage modifyhd "<absolute path to file>" --resize <size in MB>
5. For example, the command will look something like this once you replace the dummy values.
   VBoxManage modifyhd "C:\Users\WindowsLoop\VirtualBox VMs\Windows 10\Windows 10.vdi" --resize 46080
6. Close the Command Prompt window.

That is all. It is that simple to use the VBoxMange command to resite VirtualBox disk size.

Do keep in mind that the newly expanded space will be shown as unallocated space in the guest operating system. You need to manually partition the unallocated disk space in the virtual OS. You can use the build Disk Management tool in Windows to create, extend, or resize partitions.

I hope that helps. If you are stuck or need some help, comment below and I will try to help as much as possible. If you like this article, check out how to convert VMware image to VirtualBox.