I've got an early 2013 MacBook Pro with an external display connected via HDMI to the in-built port. The system shows that the resolution of built-in display (15-inch Retina) is 2880 x 1800, while the external display max reso is 1920 x 1080. So if I have a large picture / application on the external display, I should be able to drag it to the internal one and have still screen estate to spare. This isn't happening. Here are images of this very page, first on the external screen, then without resizing dragged to the internal one:

External Display

Internal Display

I can't change the resolution of either display in Display Preferences. OS is Mojave 10.4.5, and as far as I am aware everything is up to date. Can anyone suggest what's wrong, and what could I do to fix this?

  • There is no need to write "SOLVED" into the question title. You've accepted the answer below, this will also show up accordingly in any listing of the question.
    – nohillside
    Commented Aug 5, 2019 at 18:15

1 Answer 1


This is the correct behavior. The actual resolution of the panel is 2880 x 1800, but macOS scales the UI to simulate 1440 x 900 @ 2x by default.

You can change the scaling factor in Display preferences to "create" more screen space. If you set it to the highest setting, 1920 x 1200, then you'll be able to drag a window from the external to the internal display in the way you're expecting.

  • Thanks a bunch. I'm still confused why the panel shows far larger resolution than the screen actually shows. Why might this be?a Commented Aug 5, 2019 at 16:52
  • Because the higher resolution is used to make the image sharper, not to provide more space. The panel's real resolution is 2880 x 1800, but the UI is drawn as if its resolution was only 1440 x 900. So the UI is the same physical size as it was on the 2011 15" MacBook Pro (which used a 1440 x 900 panel), but it's four times as sharp, because the panel has four times as many pixels.
    – daGUY
    Commented Aug 5, 2019 at 23:57
  • OK that does make sense. But if the panel resolution is what you say, there's still a lot of unused reso left after setting the scaling factor to the highest setting. Weird :-) Commented Aug 7, 2019 at 7:06
  • There are unofficial ways you can set the screen resolution to the panel's native resolution, if you really want to. I think Apple's position is just that doing so makes the UI way too small for most people, so they don't offer it as an option in Displays preferences.
    – daGUY
    Commented Aug 11, 2019 at 15:23

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