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A Guide for Creating Scaled Resolutions in MacOS

WARNING: Try this at your own risk. I am not an expert in display hardware and am not responsible for any damage to components or system files. Additionally, this may place a greater burden on your graphics card.

Update (Dec 11, 2023):

I highly recommend you ignore this entire guide and download BetterDisplay 2! It's a fantastic application with lots of customization and Apple design language that makes this process a breeze. If you prefer to do this manually or you're curious how scaling works behind the scenes, feel free to read on. :)

Update (May 16, 2023): This process still works for MacOS Ventura, as well as for Apple Silicon! This guide has been updated with a new and hopefully easier process for scaled reslutions, but check out previous versions for past OS versions.

Background

Despite being an Apple fan and avid Mac user, something has always frustrated me about MacOS. Unlike Windows, MacOS does not offer the ability to create custom scaled resolutions without losing pixel density. However, there is a catch: If Apple deems the display to be “Retina” then you get a different resolution selector with options for “More Space” and “Less Space” that is effectively scaling the display without losing pixel density.

This can be frustrating when MacOS arbitrarily decides that a high-resolution monitor is not classified as “Retina” and cannot therefore have scaled resolutions. I have a 25” Acer G257HU monitor with a resolution 2560x1440. Running at 1440p, items along the menu bar appear too small and are hardly readable from a significant distance. However, since it is not deemed a “Retina” monitor the only true resolution-preserving options that appear are 2x, 3x, etc. resolutions. This would leave me with a scaled resolution of 720p which is too large. Instead, I want a scaled resolution of around 125% that would give me the scale of 1080p.

I knew this had to be possible since Apple’s own ancient Thunderbolt display can do it. It runs at a resolution of 1440p yet has the Retina scaling options of “More Space” or “Less Space” that allow it to preserve resolution. Thus began my hunt off-and-on for over a year that resulted in me reading many articles and corrupting many system files in my computer to no avail until I finally figured it out. Because of the time and effort I went through to get this working, I wanted to share the process for any other curious individuals interested in creating scaled resolutions. The steps are actually relatively straightforward although somewhat finnicky.

Process

Step 1: Disable SIP

In order to complete this process, you will need to have full Administrative access to your computer. iMore has a helpful article detailing the steps to disable System Integrity Protection which is necessary to modify system files.

If you are running MacOS 11 Big Sur or later, you will not be able to modify system files in the /System/Library directory. You will be working in the /Library directory instead.

For MacOS 10.15 Catalina and below, to make system files writable you will need to open terminal and type the following commands:

sudo mount -uw /

killall Finder

Now the system hard drive partition should be modifiable by the user.

Step 2: Download RDM

Sometimes System Preferences does not show all of the resolutions possible with your monitor. To bypass this, there are several free utilities that can be used. One I have found to work well is RDM.

Once you have installed RDM, it will run as a menu bar application. It allows you to see all the options for your screen resolution.

Here’s what RDM looks like on my system running a 1440p monitor with some custom HiDPI resolutions I’ve created:

In case you don't want to use RDM, there are some other nice tools like SwitchResX, EasyRes, or QuickRes. I have not used these tools enough to verify them, but you may wish to check them out.

Step 3: Enable HiDPI

In order for your Mac to support scaling, it must have the option for HiDPI (a.k.a. scaled) resolutions turned on. Most newer Macs will have it turned on by default.

If HiDPI is enabled you will see lightning bolt emojis next to resolutions in RDM as can be seen in my screenshot from above. This means that these resolutions are full-quality scaled Hi-DPI resolutions. Another way to check if HiDPI status is under Displays in System Preferences. If the resolutions are not already listed, go to Advanced and enable "Show resolutions as a list." Click Done and on the Displays page, enable "Show all resolutions." It will show several resolution options that MacOS suggests for your monitor. If HiDPI is enabled on your system, you will likely see a resolution that is ½ the size of your monitor’s native resolution that has “(HiDPI)” listed next to the resolution.

The largest HiDPI option for a 1440p monitor will likely be 720p which is a 2x scale. In order to add different resolutions, we will need to modify the file that contains these values.

If HiDPI is not enabled, you can run:

sudo defaults write /Library/Preferences/com.apple.windowserver.plist DisplayResolutionEnabled -bool true

Restart the system to enable.

Step 4: Determine Your Display

There are two methods: downloading Hackintool or manually locating the display information. Manually locating the information may not work for some monitors where color profile information is missing.

Hackintool Method

Download Hackintool from https://github.com/headkaze/Hackintool/releases.

Open Hackintool and select the Displays tab. Under this tab, all of the displays connected to the computer will be listed with their Vendor and Product IDs. Remember these values for your external monitor. They will be used for locating your display file.

Manual Method

Under Displays in System Preferences, note which color profile is being used. Select the default color profile for your computer (usually called “Color LCD” or the name of your monitor). If you are running a version below Ventura, select Open Profile.

If you are running Ventura or above, open ColorSync Utility manually, navigate to the Devices tab, select the Color Profile under Displays, and on the right panel click Open next to the path of color profile file to open the detailed color profile file.

Scroll to the last line in the file which should be called “Apple display make and model information.” Unfortunately, this item does not always exist.

The pieces of information we want from this screen are the Manufacturer and Model tags. This will allow us to find what file is being used to supply the resolutions to the system.

Record the non-zero values in the Manufacturer and Model fields. For example, my Acer monitor with my Hackintosh is 472 and 416 or my monitor with my MacBook Pro is 620 and A022.

Step 5: Locate Your Display File

Big Sur 11.0 and above: Navigate to /Library/Displays/Contents/Resources/Overrides/

Catalina 10.15 and below: Navigate to /System/Library/Displays/Contents/Resources/Overrides/

Navigate to the folder called DisplayVendorID- with the Manufacturer number of your color profile on the end. Inside this folder should be a file that is DisplayProductID- with the Model number of your color profile on the end. This file will contain the resolutions that your computer can display.

However, do not fear if this file does not exist. In this case, you will have to create the file. Thankfully, someone has made a website for this.

Step 6: Generate Resolutions

Here’s the most important part that was hindering me for a long time because I couldn’t seem to find it posted anywhere. You need to create BOTH the scaled HiDPI resolution that you want and DOUBLE that resolution.

For instance, I wanted my 1440p monitor to scale to 1080p so I needed to create entries for 1920x1080p HiDPI as well as for 3840x2160p HiDPI. Without the 2160p entry, my monitor would not accept 1080p as a HiDPI option. This had me stuck for an obnoxiously long time. Weird. I suspect this tricks MacOS into believing it is a true 2x scaling and thus is allowed instead of an arbitrary scaling value.

So let’s create the resolutions. Head to https://comsysto.github.io/Display-Override-PropertyList-File-Parser-and-Generator-with-HiDPI-Support-For-Scaled-Resolutions/.

Type the color profile model that we found earlier under the DisplayProductID field and the color profile manufacturer under the DisplayVendorID field. Next add desired resolutions. Make sure all resolutions have HiDPI selected.

Here’s what I generated for my system based on my monitor and the resolutions I desired:

If your system already has the file for your display, I recommend creating only the new resolutions you want and copying those lines into the existing file. Otherwise, click the button in the bottom right to download the file. Save it somewhere memorable. Do not change the name, as the generator creates the correct name for your monitor.

Step 7: Change Display File

If the file already exists:

Before you change the display file, make sure to create a copy. Create a copy on your desktop of the original file in case something goes wrong and you needed to reset to the original. Duplicate this newly created copy. This will be the file to change.

Open the file with a text editor and locate the section titled <key>scale-resolutions</key>. Under this is the section <array></array> which holds all of the values for the resolutions that appear in the scaled resolutions options in System Preferences. Between the array tags copy the resolutions from the website. There should already be some resolutions there. This section of the file should look similar to the below image although you may not have as many resolutions listed.

If the file does not already exist:

Copy the downloaded file into the system folder we found in Step 4 (/Library/Displays/Contents/Resources/Overrides/...) that should contain the file. If the information is put into the website correctly, the downloaded file will be readable by the computer and no editing is necessary.

Step 8: Reboot

Reboot the machine for the changes to take effect. If the file’s name and location are correct for your system, then MacOS should automatically recognize the file and see the new resolutions. Open RDM and select the resolution you wish to use. And voila! Now you can use scaled resolutions.

After a reboot the system files are no longer modifiable. System Integrity Protection (SIP) will likely stay disabled until the next MacOS update modifies the recovery partition. If you would like to reenable SIP, the link from Step 1 details the process to reenable SIP.

Final Thoughts

Feel free to contact me if you find this helpful or have more questions. I’d love to hear your feedback!

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One huge shout-out to this article:

https://comsystoreply.de/blog-post/force-hidpi-resolutions-for-dell-u2515h-monitor

This developer created the tool to generate the scaled resolutions. Their knowledge helped me immensely when getting this working.