How to Make Ubuntu Full Screen on VirtualBox in Windows 10 and Windows 11

Running Ubuntu on VirtualBox is a great way to test or use Linux without leaving Windows. But right out of the box, the window is usually small, and Ubuntu won’t go full screen. The fix? Installing Guest Additions. Here’s a step-by-step guide to make Ubuntu full screen on VirtualBox in both Windows 10 and Windows 11.

Step 1: Start Ubuntu in VirtualBox

Launch VirtualBox and boot your Ubuntu virtual machine. Make sure Ubuntu is running and you’re logged in.

Step 2: Update Ubuntu

Before installing anything, it’s a good idea to update Ubuntu. Open the Terminal (Ctrl + Alt + T) and run:

sudo apt update && sudo apt upgrade -y

Let it finish updating. This helps avoid conflicts during installation.

Step 3: Install Required Packages

Run the following command in Terminal to install the packages VirtualBox Guest Additions needs:

sudo apt install build-essential dkms linux-headers-$(uname -r) -y

This installs essential build tools and headers required for compiling the modules.

Step 4: Insert Guest Additions CD

In the VirtualBox menu (at the top of the VM window), click:

Devices > Insert Guest Additions CD image…

This mounts a virtual CD inside Ubuntu.

Step 5: Run the Installer

If a file browser opens showing the CD contents, great. If not, open Terminal and run:

cd /media/$USER/VBox_GAs_*
sudo ./VBoxLinuxAdditions.run

You’ll be prompted for your password. Let the script run. Once it’s done, restart Ubuntu:

sudo reboot

Step 6: Enter Full Screen Mode

After rebooting, try full screen by pressing:

Host + F

(By default, the Host key is the Right Ctrl key on your keyboard.)

Ubuntu should now resize automatically to fit your window or go completely full screen.

Troubleshooting Tips

• Still not full screen? Try switching to View > Auto-resize Guest Display in the VirtualBox menu.
• Guest Additions not mounting? Download the ISO manually from VirtualBox’s website and mount it in the VM.
• Wrong resolution? Go to Settings > Displays in Ubuntu and adjust it manually.

Final Thoughts

Once Guest Additions are installed, not only does full screen work, but features like shared clipboard and drag-and-drop between host and guest OS will also be available. It’s a small fix that makes a big difference in usability.

If you’re also looking to expand your virtual machine’s disk size, check out this helpful guide:
How to Enlarge a Virtual Machine’s Disk in VirtualBox or VMware