Before you begin
Make sure your Mac is running the latest version of macOS.
If your display is blank or not detected
Try these steps if you don't see an image on your display.
Check how many displays you can connect
To find out how many external displays your Mac supports, check its technical specifications page or use the Support tab in About This Mac:
- Choose Apple menu > About This Mac.
- Click the Support tab, then click Specifications.
- On the webpage that appears, the number of displays your Mac supports appears under Video Support or Graphics.
Check your cable or adapter
Disconnect the cable from your external display from your Mac, then reconnect it. If the cable from your external display doesn't connect to the ports on your Mac, you can use a Thunderbolt 3 or USB-C adapter.
If your display appears blurry
If images or text on your display appear blurry or pixelated, check the resolution and brightness of your display.
Adjust the resolution
- From the Apple menu, choose System Preferences.
- Click the Displays icon.
- Press and hold the Option key while you click Scaled to see additional resolutions for the second display.
If you're using more than one display, and you can see the image on one of the displays, you can also use Displays preferences to check for connected displays.
If the expected resolution doesn't appear for your display, check the specifications page to see what your Mac supports.
Adjust the brightness
To adjust the brightness of your Apple display, press the increase brightness key or the decrease brightness key on your keyboard.
You can also use the brightness adjustment for each connected display in System Preferences > Displays.
Displays not made by Apple sometimes have brightness and color adjustments built into the display. Check the documentation for your display to see if it includes built-in controls.