I have read many posts about screen resolutions for Ubuntu as VirtualBox guest. May be I failed to read the good one... So.

I "just" want to make more screen resolutions available WITHOUT installing/modifying anything requiring superuser access in the Ubuntu guest VM (then WITHOUT guest additions). This requirement is a mandatory security issue for my project.

I am quite confident that it must be somehow possible, because setting "GRUB_GFXMODE=1280x1024" in /etc/default/grub uses 1280x1024 in grub boot menu only. This shows that the Virtual Box virtual graphic card does support it.

PS: please don't reply anything involving guest additions..

  • forums.virtualbox.org/… says "Then you need to adjust the framebuffers of the guest. Since you are negating the guest additions it is all up to you and the guest OS. Custom xorg.conf would help too depending on the OS. But this is all out of the scope of this forum since it does not deal with VirtualBox." – user539484 May 9 '13 at 16:46



You get similar to

Screen 0: minimum 320 x 200, current 800 x 600, maximum 1280 x 1280

VGA connected 800x600+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
       1280x1024      60.0 +   75.0  
       1280x960       59.9  
       1152x864       75.0     74.8  
       1024x768       75.1     70.1     60.0  
       832x624        74.6  
       800x600        72.2*    75.0     60.3     56.2  
       640x480        75.0     72.8     66.7     60.0  
       720x400        70.1

    * item is current.

It is list of resolutions you can set. Now you can change by using

xrandr -s Index

index is number starting from 0 as the first line.


xrandr -s widthxheight

  • thx for your reply. xrandr displayq only two rows for the the low basic screen resolutions (800x600 & 640x480) looking a way to make virtualbox tell ubuntu other rscreen resolutions :) – svert Apr 25 '13 at 13:07
  • Works with 17.04 and VirtualBox 5.1, thank you . – robyschek Jul 19 '17 at 23:20

You will need to boot in EFI mode and install Ubuntu in EFI mode for this to work.

VBoxManage modifyvm "VM name" --firmware efi
VBoxManage setextradata "VM name" VBoxInternal2/UgaHorizontalResolution 1440
VBoxManage setextradata "VM name" VBoxInternal2/UgaVerticalResolution 900

Without guest additions there is no way to randomly change resolutions from the guest. You will have to pick one resolution and stick with it, though you can change resolutions between reboots. For example, power down, change resolution, boot.

You would be much better off making an image with Guest Additions already installed, and just using that as your locked down base image. However the commands above will work.

There is a lot of data about running without guest additions here.

You may wish to use a resolution of 1920x1080 and enable "scaling mode" so the window can be re-sized. It's not the same as changing resolutions but it is a good start at it.


I found this. It may help/work for you:

Close virtualbox, open a terminal and type:


Replace HORIZANTALAMOUNTOFPIXELSHERE with the horizontal amount of pixels and VERTICALAMOUNTOFPIXELSHERE with the vertical amount of pixels. This will set the resolution for virtual machines without guest additions.

It, unfortunately, only worked with openSUSE for me (haven't tried with Ubuntu yet), but you can try it and hopefully it works for you.


1) Stop XOrg

 stop lightdm

2) Open console


3) Create default xorg.conf, it not exists

X -configure

4) Move xorg.conf.new so system uses config file

mv xorg.conf.new /etc/X11/xorg.conf

5) Reboot


6) Modify xorg.conf, add

Section "Monitor"
 HorizSync 1.0 - 1000.0
 VertRefresh 1.0 - 1000.0
 Option "MinClock" "1.0"
 Option "MaxClock" "10000.0"
 Option "Primary" "True"
 Option "PreferredMode" "1920x1080"

7) Reboot


8) System Settings > Display > "Select Any -4:3- Resolution"

9) Enable widescreen

Host:VBoxManage setextradata "YOURGUEST" "CustomVideoMode1" "1920x1080x32"

I had the same problem when I installed an operating system that shall not benamed. I would have used guest additions but Oracle does not make one for that system.

I did manage to work around the two features I missed: sharing files and changing resolution.

Actually, I did not change the resolution so this may not be what you want.

I just wanted to change the window size and found I could do that in for the machine in Virtual Box. If that is what you want to do, here is what I found.

Go to settings->display and change the scale factor and change it. The guest machine's "resolution" remains the same but the screen is now viewable.

By the way, since the machine first boots into EFI, I tried some of the VboxMaanage solutions here and they did not work.

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