I am new to VirtualBox and am trying to set up an instance of Windows 7 64.

I have the virtual machine instance running with Windows 7 now installed, but it only fills up a small portion of my screen. Even when I go full screen, the window stays the same size and the rest of the screen is filled with gray space.

I have installed VirtualBox Guest Additions, which allowed me to go from a resolution of 800x600 to 1024x768, but this still isn't satisfactory as my laptop display is 1600x900.

Any help on this would be most appreciated. Thanks.

  • 1
    can you post a screenshot with VB at fullscreen mode?
    – Sathyajith Bhat
    Apr 3, 2012 at 16:45
  • I'm having a similar problem, though it cropped up out of nowhere after things had worked properly for about 2 years. Mountain Lion host, XP guest, VBox v4.2.6. I increased the VM's total memory and video memory to no avail.
    – psoft
    Feb 6, 2013 at 4:35
  • Just figured it out for myself - see answer.
    – psoft
    Feb 6, 2013 at 4:42

7 Answers 7


You must install guest additions. In the "Devices" menu in the virtual machine's menu bar, VirtualBox has a handy menu item named "Install guest additions", which mounts the Guest Additions ISO file inside your virtual machine. A Windows guest should then automatically start the Guest Additions installer, which installs the Guest Additions into your Windows guest. After that your virtual OS scren will be automatically change resolution to fill entire screen.

  • 8
    For my case I found this answer not explicit enough. For OSs: MAC OS(host), Win(guest): 1.Applications > right-click VBox.app > locate VBoxGuestAdditions.iso 2.In VirtualBoxManager > Storage > drag&drop .iso file here. 3.In the host machine menu Devices > Optical Drives > select .iso file. Then open cd drive in Windows and install guest editions with double-click on .exe file. Finally, reboot.
    – boldnik
    Jan 27, 2016 at 20:51
  • Thanks Arterius. This helped me when I installed Windows 10 in Debian Stretch using Virtualbox 6. Jul 25, 2019 at 22:04

Try increasing the virtual graphics adapter's memory to 64 or 128M. That might help. You may also want to see if you can change the screen resolution from within the guest OS.

  • 7
    Additionally, I had to set scaling to 200% to get a readable screen (everything was very small)
    – grooveplex
    Feb 13, 2019 at 15:49
  • These two comments worked perfectly for me, thank you!
    – Liran H
    Dec 4, 2019 at 14:48
  • Mine was on 16MB, no wonder it struggled! Thank you
    – Edgar H
    Sep 18, 2020 at 16:52
  • Changing the resolution worked for me, thank you!
    – Meir Gabay
    Jan 9, 2021 at 11:49
  • After applying both these suggestions (increasing the display video memory in VirtualBox as well as increasing the display resolution from within the guest OS), the issue went away for me. Feb 23, 2021 at 21:10

Auto-resize Guest Display

After leaving the comment on your original question, I figured out my problem. I had hit Command-G instead of Command-F. On Mac host, Command-G toggles an "Auto-resize Guest Display" setting. That fixed it.

  • All that does is take you to full screen. May 27, 2014 at 13:27

There might be three causes as far as I know:

  • Either your video card doesn't support such high resolution: as BobTsaid you can try tuning your video card settings in the VM properties
  • Or it may be that the resize event is not interpreted correctly by VirtualBox: what happens if you resize the window by dragNDropping the corner to a resolution higher than 1027*768? If this works (allowing you to go higher than that), then you should try entering and leaving full screen several times
  • And if you are using an application that takes full control of the screen (eg. a game), and that application doesn't support your target resolution, then not much can be done.

You need to reboot VM after installing guest additions, and then select options to auto-resize guest display etc to your liking.


I had the same problem and my Guest Addition was installed correctly. I read BobT suggestion above and checked my adapter graphic memory and it was using 128 MB. I changed it to 256 MB and everything got fixed. Then changed it back to 128 MB and now everything is fine :)
So maybe just a change is need to hint VB graphic adapter.
Hope it works :)


There is a menu option in VirtualBox GUI under Screen > Go to full screen; also accessible through Host + F by default. (you can configure the host key in VBox options).

During a fullscreen session you should have a hidden bar on the bottom of the screen with restore tools: just tap the bottom of the screen with the mouse pointer.

  • 5
    Yes, I understand that, but what I'm trying to say is that once it is in full screen, the viewable portion of the virtual machine OS is still set to 1024x768 and all although the VirtualBox program is filling the whole screen, everything around the OS window at 1024x768 is just filled with gray. So I can't make the screen fill my entire display.
    – jdavis
    Apr 3, 2012 at 16:33
  • Sorry, I understood the question wrong: see my other answer
    – PPC
    Apr 3, 2012 at 18:27

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