Auto resize screen size for Windows 10 guest VMs in Virtualbox

After installing a guest operating system (OS) on VirtualBox, the interface of the guest OS is displayed in a windowed mode by default. Moreover, the size of that window is usually not big, and if you maximize the window’s size, the resolution of the guest OS user interface is left the same. In the majority of cases, working in a guest OS with low resolution is not comfortable. Don’t worry, however, as it is possible for you to increase the screen resolution of the guest OS user interface as well as run a guest OS in the full screen mode. Read today’s blog post to learn how to make VirtualBox full screen for Mac OS X and Windows guest OSs.

  

How to Make VirtualBox Full Screen for Windows 10 Guests

If security is a concern for you, running Windows 10 as a virtual machine (VM) on VirtualBox is a good idea. 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. 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.

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).

Check the amount of video memory you have in the virtual machine settings. 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. You can also enable 2D and 3D acceleration.

 

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, but you still have no ability to switch the full screen mode on. 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 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.

In order to fix this issue and make VirtualBox full screen, you should install VirtualBox Guest Additions on the guest OS.

[Solved] Automatic resizing of Screen resolution

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.

 

In the guest Windows system open Windows Explorer, go to the virtual CD drive (disk D: in this case) and run VBoxWindowsAdditions-amd64.exe file to install VirtualBox Guest Additions on the Windows 10 guest.

 

The process of installing Guest Additions is quite straightforward. After finishing the installation, reboot the VM.

Higher screen resolution in VirtualBox?

Once VirtualBox Guest Additions are installed, you can see a different set of resolution settings in the Windows 10 guest. In the VM Window menu, go to View and make sure that the Auto-resize Guest Display option is enabled.

Move the mouse pointer over the corner of the VM window, push the left mouse button and change the size of the VM window. The resolution of the user interface of guest Windows 10 is automatically changed. Now you can maximize the VM window size of the Windows 10 guest.

We are now close to answering the “how to make VirtualBox full screen Windows 10” question. After making the configuration explained above, you can enable the full screen mode for your Windows 10 VM by clicking View > Full Screen mode in the VM window. As an alternative, you can press the combination of the VirtualBox Host key and F. Right Control is the default host key in VirtualBox, hence, you should press Right Ctrl + F to enter full screen mode for a Windows 10 VM.

How to Make VirtualBox Full Screen for Mac OS X Guests

After installing macOS on VirtualBox, the default screen resolution of the guest OS is 1024x768. Display Settings of macOS can be found in System preferences > Display. You cannot increase the screen resolution in the display options. Only the 1024x768 resolution is available in these settings.

 

Before you can increase the display resolution for your macOS running on a VM, go to VM settings > Display, and make sure that the amount of video memory is 128 MB and the Enable 3D acceleration checkbox is ticked (similarly to the process explained above for the Windows VM).

Let’s now go to configuring the display resolution of the macOS guest.

Power off your macOS VM.

Open the console in your host machine. In our example, Windows 10 is used as a host machine, hence, we have to run CMD as Administrator.

Go to the VirtualBox directory; the default installation path of VirtualBox is C:\Program Files\oracle\virtualbox

cd "c:\Program Files\oracle\virtualbox"

Set the necessary resolution with VBoxManage which is a command line configuration tool of VirtualBox. The defined resolution can be less than or equal to the resolution of your physical monitor connected to your physical (host) machine. In our case, the monitor has the FullHD resolution (1920x1080). Let’s run the command in the host OS to set the necessary resolution.

VBoxManage setextradata "macOSMojave10-14" VBoxInternal2/EfiGraphicsResolution 1920x1080

If you use Linux or macOS on a host machine, the configuration principle is similar – run VBoxManage with the similar parameters.

Power on the VM.

Now you should notice that the VM display resolution in the VM window is higher right after powering on the VM (during VM boot). When a VM boots, you will see your resolution in the display settings of the macOS guest. There is still only one resolution parameter in the list, but it is 1920x1080 now instead of 1024x768 seen previously.

Press the combination of the host key and F. In this case, this is the Right Ctrl + F key combination. As an alternative to the key combination, you can click View in the VM window and hit the Full-screen Mode option.

Now your guest macOS running on VirtualBox is running in the full screen mode.

Advantages of this method: Ease of use.

Disadvantages of this method: You need to shut down a VM to change screen resolution in the VirtualBox VM window.

Since VirtualBox v.6.0.0 was released, VirtualBox Guest Additions have been provided for macOS guest OSs, while earlier versions of VirtualBox did not include Guest Additions for macOS. Unfortunately, the current version of macOS Guest Additions does not contain macOS graphic drivers to change the VM display resolution automatically when stretching or maximizing the guest VM window. Only the basic functionality is available right now, which means that you cannot use the same method of changing screen resolution as for Windows and Linux guest OSs running on VirtualBox after installing Guest Additions.

How to Make VirtualBox Full Screen for Linux Guests

First of all, make sure that in the virtual machine display settings (Machine > Display), the amount of video memory is 128 MB (as was the case for the previous two examples).

Install VirtualBox Guest Additions on your Linux guest.

Let’s explore how to make VirtualBox full screen for Linux guests on an example of using Ubuntu. You can install VirtualBox Guest Additions on Linux, as was shown in the first section for Windows by inserting the ISO disk image into a virtual CD/DVD drive of a VM and running the installer for the appropriate platform. We considered this method in the blog post about installing Ubuntu on VirtualBox. Installing Guest additions from online package repositories with your package manager is possible, but at this time there remain some disadvantages caused by package dependencies. Hence, it is recommended to install Guest Additions from a virtual ISO disk at present.

In order to install Guest Additions and make VirtualBox full screen for Linux guests, do the following:

• In the VM window hit Devices > Insert Guest Additions CD image.
• If autorun is enabled, you will see the autorun window. Hit Run and enter your password to confirm running the installer.
• Type y and press Enter in the appeared console window.
• After finishing installation reboot the Linux VM.

Now you can change the size of the VM window, and the resolution of your guest Linux will fit the size of the VM window automatically. Go to View > Full screen mode or press the Host+F combination to make VirtualBox full screen for your Linux guest.

Note: If for some reason, you cannot install VirtualBox Guest Additions on your guest OS, you can manually and statically increase the resolution of the guest OS display by using VBoxManage (a VirtualBox command line configuration tool) on a host OS as explained above in the macOS configuration section:

VBoxManage setextradata "VM_name" VBoxInternal2/EfiGraphicsResolution 1920x1080

Conclusion

Using a full-screen mode for a virtual machine is convenient and allows you to appreciate the advantages of hardware virtualization. This feature allows you to use the guest OS on the VM much as it would be used on a host machine for high resolution applications, large workspace, etc. Today’s blog post has explored how to make VirtualBox full screen for Windows, and macOS and Linux guest OSs running on VMs.

The first method is using VBoxManage, the command line VirtualBox management tool, for changing resolution manually. This method can be used for all available OSs – Windows, macOS and Linux. The disadvantage of this method is that you have to shut down the VM to change the guest OS display resolution. Use this method only if it is impossible to install VirtualBox Guest Additions on a guest OS. Automatic changing resolution in real time when resizing a VM window or entering a full-screen mode is possible for Windows and Linux guests after installing Guest Additions. This is the second method that is available. Unfortunately, the current version of VirtualBox Guest Additions for macOS (v.6.0.8) does not contain special display drivers for changing resolution and entering a full-screen mode in macOS guests automatically.