while exploring different possibilities of my monitor with different resolutions I have been using xrandr. I wish to know what one of the outputted data of xrandr means.

In the following example I would like to know what the final data set means (the part stating 890mm x 500mm)

HDMI1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 890mm x 500mm

What are these Dimensions specifically, and are these parameters changeable?

  • My guess is, its the mm size of the screen itself not the chassis. – Videonauth Apr 28 '16 at 7:54
  • @Videonauth - I get different ouputs of this parameter depending on the stauts of my monitor being turned off or on. ON=890mm x 500mm OFF=708mm x 398mm – Kalamalka Kid Apr 28 '16 at 7:56
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    Maybe a kind of default setting to go to when it doesnt get data from the monitor. Curious if the On measurements would fit to your monitor. – Videonauth Apr 28 '16 at 7:58
  • xrandr uses metric (mm) while Ubuntu System Settings shows monitor size in inches (55") – Kalamalka Kid Apr 28 '16 at 8:00

What it means

In the line:

HDMI1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 890mm x 500mm

indeed, the last section: 890mm x 500mm gives you the size of your screen x/y in mm

Why the difference?

In this question, we ran into the same issue. The explanation is that by default, the screen is "assumed" to be at 96dpi, which is not necessarily the case. If the screen is on, the value is set form the "real" resolution (pixels/inch), which is obviously slightly different on your screen.

this bug is related to the issue; you would probably get the same difference when getting the screen info via xdpyinfo. Note that the xrandrsize with screen on is the correct size.

Obviously, you cannot change these values.

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    @KalamalkaKid I tend to think not, since it is purely a "virrtual", informational rendering of the size. On the other hand, do you have a (set of) screenshots (before/after)? It would be interesting to measure if the changes are of the same ratio. – Jacob Vlijm Apr 29 '16 at 5:00
  • ok I was thinking the same thing, so I updated my answer on the other post, (included some more information about some buggy behavior), and also included the screenshots askubuntu.com/questions/742897/… – Kalamalka Kid Apr 29 '16 at 6:14

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