Why your M1 or M2 MacBook shows only one external monitor

Why it happens

Each Apple chip can drive a fixed number of screens. The plain M1 and M2 chips run the built-in screen plus one external display, so a second monitor stays black even when it's plugged in correctly. A normal hub, dock or adapter can't raise that limit.

How to fix it

1. Choose Apple menu > About This Mac. Note the chip, such as Apple M1, M2 or M3, and the model name at the top.

   Apple menu›About This Mac

2. Look up your model's Tech Specs on Apple's support website and read the Display Support section. It gives the exact number of external displays your Mac can use.

3. MacBook Air with M3: connect both displays, plus power, a keyboard and a mouse, then close the lid. Both external displays should light up.

4. MacBook Air or 13-inch MacBook Pro with M1 or M2: only one external display works. The same goes for the 14-inch MacBook Pro with the plain M3 chip. Pick the display you want and connect only that one.

5. Mac mini with M1: it supports two displays, but one must use the HDMI port and the other a Thunderbolt port.

Still not fixed?

1. Chaining one display through another doesn't help. Every screen still counts toward your Mac's limit.

2. Some docks add extra screens with their own driver software. They can be fine for documents, but video and scrolling may stutter, so check the dock maker supports your macOS version.

3. If a display your Mac should support isn't showing, open Displays, hold Option and click Detect Displays. Then try another cable and restart.

   Displays›Detect Displays

4. Need two or more screens every day? A Mac with a Pro or Max chip, or a MacBook Air with M4, runs two external displays with the lid open. Check the Tech Specs before you buy.

5. If your Tech Specs list two displays and one still stays black with a known-good cable, contact Apple Support or a repair shop. A faulty port is a hardware repair.