Hopefully, this doesn't sound like a dumb question, but I'm wondering if the "Looks like" resolutions listed for each scaling mode in System Preferences > Displays are the true resolutions one would be running at/seeing when using any of them.

What made me interested in finding this out is when I read that the 2880x1800 resolution shown in About This Mac on the Early 2013 15" Retina MacBook Pro (and I assume many others) was not actually easily accessible without a tool like Retina Display Master (RDM). So I got it here: https://github.com/avibrazil/RDM, and through this video: https://www.youtube.com/watch?v=tG42tS2wTK4, found there was a more updated fork of it (https://github.com/usr-sse2/RDM/tree/2.3.2), which is fully compatible with Catalina (that apparently allowed you to set custom HiDPI resolutions by disabling SIP).

At some point between finding out about RDM's existence and the updated fork of it, I also found out you could scale said 15" display not to just 2880x1800, but a ridiculous 3840x2400.

To keep this from being an unnecessarily long question/post (might be a bit too late for that), I am trying to keep the 3840x2400 resolution (potentially for the sake of things like 4K video or photo editing) while having the UI not be so small and difficult to read.

As of writing this, I currently believe that picking one of the larger scaling options in System Preferences > Displays is actually showing that "Looks like" resolution (this is because RDM shows the current resolution in its menu bar icon, though I have no other way to confirm this, which is why I'm asking the question) not a possible higher resolution(?).

One of the things I can do when using the higher resolutions is to make the Dock (a lot) bigger, which is helpful but doesn't nearly solve the problem in its entirety.

This issue on the original RDM repository seems to explain basically what I'm thinking, just far simpler: https://github.com/avibrazil/RDM/issues/40

Again, hopefully, at least some of this makes sense to people and doesn't come across as complete nonsensical garbage.

Additional note: Disabling SIP and trying to add a "custom" HiDPI 3840x2400 in RDM (which to me sounds like it would double the size of UI elements while retaining that resolution) did not appear to do anything, or at least not what I thought it would do.

2 Answers 2


The point to remember is that the display is a physical grid of pixels. They do not grow larger or smaller; they do not increase or decrease in number when you 'change the resolution'.

It's all a trick of software. Does this shape take up 12 pixels, 6 pixels, or 3 pixels with a bit of blur spilling onto next door's pixels?

My advice is to set the display to the default 2x scaling and don't give it any more thought. I certainly wouldn't disable SIP.

Your laptop's display is too small to show 'pixel for pixel' 4K video. You're not going to get extra detail because some software is faking a larger screen size than you actually have.

  • I don't think RDM is doing any kind of supersampling or faking, I believe it's just what the actual panel is capable of displaying. I could be wrong though. Still helpful information nonetheless. Commented Aug 29, 2020 at 13:00
  • @bennettisawesome The 15" 2013 MBP has 2880 x 1800 pixels. No more, no less.
    – benwiggy
    Commented Aug 29, 2020 at 13:58

The answer to your question really depends on the definition of the "true" resolution.

Some people would say that the resolution that the actual display uses is the "true resolution". This means that this is the actual "pixels" you can turn on/off.

If you use this definition, the "Looks like" resolution is not the true resolution. The "true resolution" is much higher, usually double of that. However "Looks like" means that things on screen appear as if the resolution was that, but pixels have been doubled (or nearly doubled) in order to improve sharpness and clarity while maintaining an actual physical size of letters, shapes, etc. that is not too small for you to be able to read.

For example you might have a 4k display capable of displaying 3840x2160 pixels. You might choose a setup here that "Looks like" 1920x1080. The actual resolution in terms of pixel data sent to and shown on the display is 3840x2160, but user interface elements, font sizes, etc. have been scaled so that in terms of physical size it looks like you had a 1920x1080 display of the same physical size. The benefit you get is that text and other elements are "clearer" on screen.

  • This is very helpful and HiDPI makes a lot more sense now, thanks. Just for clarification, does this mean I should use 1920x1200 HiDPI/"More Space" for 3840x2400 (in "sharpness"?) but with not ridiculously tiny UI elements? Will 4K video play properly as 4K video (when full-screened I guess) in the 1920x1200 mode? Commented Aug 24, 2020 at 9:31

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