Apple’s macOS Mojave disables subpixel antialiasing, also known as font smoothing, by default. On a MacBook Air or a desktop Mac hooked up to a non-Retina display, upgrading will make your fonts look worse.
Update: As some eagle-eyed readers have noticed, the below trick doesn’t technically enable subpixel antialiasing. However, this does increase font weight, which makes fonts look less jagged and all-around better on the MacBook Air and other low-resolution displays.
Here’s the Difference
Subpixel antialiasing is a trick designed to make fonts look better on lower-resolution displays. Without this feature enabled by default, macOS Mojave makes text look thinner and more blurry on non-Retina displays.
While subpixel font smoothing is disabled by default, you can re-enable it with a terminal command. There are four possible settings: 0 (disabled), 1 (light smoothing), 2 (medium smoothing), and 3 (heavy smoothing).
Here’s what they look like:
We don’t recommend enabling subpixel antialiasing if you have Mac with a Retina display. Fonts should look nice and readable on a Retina display even without subpixel antialiasing. But, if you have a non-Retina display, we recommend re-enabling this feature.
How to Enable Subpixel Antialiasing
You must run a terminal command to change your subpixel antialiasing settings. To open a Terminal window, press Command+Space to open Spotlight search, type “Terminal,” and press Enter. You can also open a Finder window and head to Applications > Utilities > Terminal.
Copy and paste one of the following commands into the Terminal window and press Enter.
Light font smoothing (1):
defaults -currentHost write -globalDomain AppleFontSmoothing -int 1
Medium font smoothing (2):
defaults -currentHost write -globalDomain AppleFontSmoothing -int 2
Heavy font smoothing (3):
defaults -currentHost write -globalDomain AppleFontSmoothing -int 3
No font smoothing (0):
defaults -currentHost write -globalDomain AppleFontSmoothing -int 0
Sign out of your Mac and sign back in. Your changes won’t fully take effect until you do.
Feel free to try different font smoothing levels. You’ll just have to sign out and sign back in before you can see your changes after running each command.
This process was tested on macOS Mojave developer beta 3, also known as macOS Mojave public beta 2.