CrackMacUnderscan on a Mac: where it is, why it's missing, and what to do instead
The Underscan slider is in System Settings, Displays, but it only appears when you select a TV that macOS recognises as one. Computer monitors, many adapters and the MacBook's own screen never get it. If the picture is cut off on a TV, the TV's picture size setting is the more reliable fix. And if you were hoping underscan would shrink the picture on a damaged MacBook screen, it can't, but there are ways that work.
Where to find underscan on a Mac
- Connect the TV and wait for the picture.
- Open System Settings, Displays.
- Select the TV at the top of the window.
- Look for the Underscan slider below the resolution options, and drag it until the menu bar and the Dock are fully visible.
Using an Apple TV with AirPlay? The setting lives on the Apple TV instead: in its AirPlay settings, turn on AirPlay Display Underscan.
Why the underscan option is missing
- It isn't a TV. macOS offers underscan only for displays that identify as TVs. Computer monitors show every pixel exactly, so they never get the slider.
- An adapter or hub is in the way. Some USB-C hubs pass the TV on as a generic display. Try a plain USB-C to HDMI cable, or the Mac's own HDMI port if it has one. Which adapter to use.
- The resolution was changed. People in Apple's forums report the slider disappearing after picking a different resolution or changing the cable. Set the TV back to its default resolution and check again.
- It's the MacBook's own screen. The built-in display never offers underscan. More on that below.
Underscan keeps resetting
Many people find the setting forgets itself after sleep, after unplugging the TV or after a macOS update. Apple hasn't published a fix. The reliable way round it is to stop needing underscan at all, by making the TV show every pixel:
- In the TV's picture settings, find Picture Size or Aspect Ratio and choose Just Scan, Screen Fit, Full Pixel or 1:1. The name depends on the brand.
- Some TVs only offer that when the HDMI input is labelled as a PC or computer. Rename the input in the TV's settings.
- Then set the Mac's Underscan slider back to zero. With nothing to remember, there's nothing to reset.
More help with TVs: MacBook HDMI not working on a TV and mirroring a MacBook to a TV.
Underscan on a MacBook's built-in screen
This is the case macOS doesn't cover. People usually want it because part of the screen is cracked, black or covered in lines, and a smaller picture would step around the damage. But the built-in display always draws across every pixel. Resolutions only change how large things look, and custom resolutions fill the whole panel too.
What works instead:
- A virtual screen streamed onto the working part. BetterDisplay can do this, and it shrinks the whole desktop to fit. How it compares with CrackMac.
- CrackMac. It leaves the resolution alone and tells macOS where the good glass ends. Windows, the menu bar and the pointer stay inside that area, and the damaged strip is painted black. Nothing is scaled, so text stays sharp. More on blocking off part of a Mac screen.
- An external monitor, if you work at a desk. How to connect one even when you can barely see the screen.
If the damage runs along one edge, CrackMac can keep windows, menus and the pointer off it. There's a free 30-minute trial.
Quick answers
Where is underscan on a Mac?
Open System Settings, Displays, and select the TV in the list of displays. If macOS supports underscan for that TV, an Underscan slider appears below the resolution options. Drag it until the edges of the picture are visible.
Why is there no underscan option on my Mac?
macOS only shows it for displays that identify themselves as TVs. Computer monitors, many USB-C hubs and adapters, and the MacBook's built-in screen never get the slider. Fix the picture on the TV instead, with a picture size setting such as Just Scan or Screen Fit.
Can I underscan a MacBook's built-in display?
No. macOS doesn't offer underscan for the built-in screen, and every resolution fills the whole panel. To keep a damaged part of the screen unused, you need an app that confines windows and the pointer, or a virtual screen streamed onto the working area.
Wanted underscan for a damaged MacBook screen?
Underscan was never going to reach the built-in display. CrackMac does the job it can't: it keeps windows, the menu bar and the pointer off the damaged strip and paints that strip black, without shrinking or blurring the rest.
- Works on macOS 13 or later, Apple silicon and Intel.
- Free for 30 minutes of use, then a one-time price. No subscription.
- A refund within 7 days, no questions asked.