How to Make VirtualBox Full Screen for Windows 10 Guests

VirtualBox is a popular virtualization software that allows you to run multiple operating systems on a single machine. One of the most common issues users face when running Windows 10 as a guest OS on VirtualBox is the inability to switch to full screen mode. In this article, we will explore the reasons behind this issue and provide step-by-step instructions on how to make your VirtualBox window full screen.

Installing Guest Additions

The process of installing Guest Additions is quite straightforward. In the guest Windows system, open Windows Explorer and go to the virtual CD drive (disk D: in this case). Run the VBoxWindowsAdditions-amd64.exe file to install VirtualBox Guest Additions on the Windows 10 guest.

Inserting Guest Additions CD Image

In the VM window, go to Devices > Insert Guest Additions CD image to insert the ISO disk into the virtual CD drive of the VM. This will allow you to access the Guest Additions installation package and complete the installation process.

Fixing Full Screen Mode Issue

To fix this issue and make VirtualBox full screen, you should install VirtualBox Guest Additions on the guest OS. If you try to enter the full screen mode by clicking View > Full screen mode in the VM window or by pressing the combination of the VirtualBox host key and F (Right Ctrl + F in this case), the guest OS screen will not be stretched to the size of your display and resolution will not be increased.

Increasing Guest OS Resolution

For example, in our case the resolution of the monitor is 1920x1080 and the maximum resolution in the Windows 10 guest settings is 1600x1200 (available resolution settings of the guest OS are not for widescreen displays, as you can see). If you go to Windows 10 display settings (right click the desktop and select Display settings in the context menu), you can increase the guest OS resolution. However, you still have no ability to switch the full screen mode on.

Enabling 2D and 3D Acceleration

It is recommended that you set 128 MB of video memory, as when a video mode with higher resolution is used, more video memory is needed. If you try to maximize the VirtualBox VM window right after installing Windows 10 on a VirtualBox VM, the size of the guest OS user interface is not increased (see the screenshot below).

Checking Video Memory

Check the amount of video memory you have in the virtual machine settings. As you recall, VirtualBox is installed on the host OS running on a host machine (a physical machine) and the guest OS is the operating system running on a VM.

Disabling Internet Connection

You can disable the internet connection or set up a virtual network adapter for a VM in the Host Only mode to allow network communication only between host and guest systems, and deny connecting the Windows 10 guest to external networks, including the internet. This is particularly useful if security is a concern for you.

Running Windows 10 as a virtual machine (VM) on VirtualBox is a good idea if security is a concern for you. By following these steps, you can make your VirtualBox window full screen and enjoy a seamless experience running multiple operating systems on a single machine.

Additional Resources

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