Display scaling (rant)

I going to rant about scaling on computer screens. Until 2006 I was solely on Windows computers. There was a setting in the display driver to adjust the scaling so that 1” on the display was 1” on the rulers in the applications. Then the system font size could be adjusted to your comfort. Macs don’t have the capability of adjusting the scaling other than by changing the screen resolution. I found this an issue when I switched my father (age 87 at the time) to a Mac in 2007 and had to reduce resolution so he could see the screen. Now I afraid that because of vision degeneration I will want to do that for myself, however at least with the “Retina” displays there are several choices that don’t degrade the image. But it still isn’t as good as it was with Windows 15 years ago and I expect remains true today.

Which brings me to rant #2. What is 100% scaling mean in an application? With the properly adjusted Windows computers I had, I knew that I could hold a ruler to the screen and it would match. Printing was a different story as often an inch in the application would not be an inch in printed output, an issue that the Mac doesn’t have, thank goodness!

Of the apps I’ve got, only Affinity’s apps and LibreOffice match the ruler at 100%. Most others seem to require 150% on my 27” iMac and 184% (if I can set it) on my 16” MacBookPro. EazyDraw is unusual in that it has “Zoom→Calibrate” which sets it accurately but reads as 150%/184%.

Open Preview on an image and it ignores the pixels per inch — a four inch wide image (1200 px, 240ppi) displays as 11” wide, basically displaying 1:1 image to display pixels when the setting is “actual size”. Maybe I can excuse that. In Lightroom Classic and Pixelmator it’s 5 ½” wide at 100%, neither of which make sense. Affinity Photo gets it right.


Oddly I ranted about Windows scaling on my blog recently and how I felt it’s worse than macOS. There, programs can ignore the scaling settings until you log out and log in again, and as I’ve recently found, apps I was launching in one way were reflecting my scaling options whilst if I launched it in another were not. It was driving me mad!

At least on the Mac, once I set the scale, everything works as it should.


Agreed. When I switched to macOS in 2016, I was very pleasantly surprised to discover that scaling actually, you know, worked. That used to be one of the Windows settings you know you should just forget it exists.

Perhaps Windows worked this way (and still may work this way) in part because Windows systems would be used in places where folks would want to hold up a ruler to measure distances on the screen. Being in the science/engineering discipline, I can appreciate why.

And here you have it. We did not send folks to the moon using calculations made from values obtained by holding rulers up to computer screens.

In the end, I am somewhat lightly amused by your fluster even as I oft face the same confusion. Are you still needing to hold up a ruler to your screen? Really? To get resolutions down to the … say … 1/8th inch … with high precision? Really? Why?

Perhaps if you came to terms with why you need both absolute distance accuracy on the screen as well as variable object resolution on the screen, your choices for the apps and settings would be a bit clearer.

If you do continue BTW, switch to a millimeter ruler. While Jimmy Carter never got his way to enforce the mi → km conversion on interstates, you might breath a bit easier knowing that you only have factors of 10 to scale for decimals (rather than those damn confusing decimals from the factors of 1/6ths and 1/8ths and …).


Maybe it’s my engineering background that I want one inch on the display to be one inch in real life. It’s useful for visualizing and is convenient if I’m say drawing a figure in application A that I want to paste in a document in application B.

I feel the same way: The scaling in Windows seems terrible when compared with on the Mac. In Windows, no matter what I try, on a 4K display things are either tiny or fuzzy.

I’ve had better results selecting my scaling factor (200%) and then selecting the offending apps and overriding the DPI scaling in the settings by using the following guide. When I now launch it, it seems far better. I ditched Launchy as that was causing me issues and was ignoring my overides.

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My experience with Windows ended about 15 years ago, which was pre-hi dpi/Retina. It seems like high resolution improved MacOS, which really embraced it. Windows floundered over it, probably because OS and hardware are separate companies and slow adoption of high resolution displays in the PC world to keep costs down.

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