How to Extend Display on macOS

If you want to increase your Mac’s desktop canvas, you can connect a second screen to it. When you extend the display, the primary and secondary screen work side-by-side. This makes it easier for you to multitask and manage your overall workflow.

You can extend the display of your Mac either wired or wireless. For a wired connection, you’ll need an HDMI cable to pair your Mac with a second screen. Whereas, AirPlay is a great way to extend your display wirelessly. However, your second screen must also support the AirPlay feature to do so.

Before You Begin

Depending on your Mac’s model, it can support multiple numbers of external displays. To check how many extra screens your computer can handle, you have to check your video adapter specifications.

1. Open Finder.
2. Click Apple > About This Mac from your menu bar.
   
3. Navigate to the Support tab.
4. Click on Specifications that’s beside Mac Resources.
   
5. In the Video Support section, you can see how many external screens your Mac can support.

Connect Second Screen Wired

The easiest way to connect a second screen on a Mac is by using an HDMI cable. But, MacBooks usually don’t have an HDMI port on them. If so, you can invest in a USB-C to HDMI adapter.

To use the USB-C to HDMI adapter, your computer must have either Thunderbolt 3 or Thunderbolt 4 ports. But if your Mac has Thunderbolt 1 or Thunderbolt 2 ports, you have to use a Mini DisplayPort to HDMI adapter instead.

First, plug in the HDMI cable to the HDMI-Out port of your computer. Use an adapter to bridge the connection if your Mac doesn’t have an HDMI port. Then, connect the other end of the HDMI cable to your second monitor’s HDMI-In port. Once the video cable is connected to the respective ports, you can extend your Mac’s display.

Step 1: Extend Your Display

When you connect a second screen, your Mac’s display should extend by default. The extended display will act like a separate canvas, rather than a mirrored screen. This way, you can open one application on your Mac and run a different process on your extended screen.

However, if your second screen mirrors/duplicates your Mac and you see the same image on both of them, you’ll have to manually adjust your display settings.

1. Plug in your second screen.
2. Then, open Finder.
3. Go to Apple > System Preferences from the menu bar.
   
4. Click on Displays.
5. Navigate to the Arrangements tab.
6. Here, uncheck the option for Mirror Displays. This will now extend your Mac’s display.
   
7. On this Arrangements tab, there are multiple screen icons depending on the number of displays connected to the system.
8. Drag one of these icons and drop it to either side of the other to rearrange your display as you see fit.
   
9. The screen with the white horizontal bar is the primary screen.

Step 2: Scale Your Second Screen

More often than not, when you extend your display, the resolution of your second screen can be imperfect. This happens when your second monitor’s display properties do not align with that of your Mac. However, you can alter the resolution from your System Preference panel.

1. Plug in your second screen.
2. Then, open Finder.
3. Go to Apple > System Preferences from the menu bar.
   
4. Click on Displays.
5. On your second screen, a separate Displays window will open.
6. Here, choose your Resolution to be Scaled.
   
7. Now, select the optimal resolution for your second screen.
8. When you get a prompt message, click Yes to scale your display.

This is how you extend your Mac’s display using an HDMI cable. The resolution is now optimal for both of your displays and you can start working on this extended desktop canvas.

Connect the Second Screen Wirelessly

To connect a second screen wirelessly, you need to AirPlay your Mac to that screen. This is usually possible with devices that independently support the AirPlay feature, like Apple TVs, some smart TVs, and other Macs.

1. First, make sure AirPlay is enabled on your second display.
2. Then, open Finder.
3. Go to Apple > System Preferences from the menu bar.
   
4. Click on Displays.
5. Enable the option to Show mirroring options in menu bar when available.
6. Click on AirPlay Display and select your second display from the dropdown list.
   
7. If an AirPlay Passcode pops up on your second screen, type it on your Mac and hit OK.
   
8. The second display should now mirror your Mac.
9. Then, on the menu bar, select the Screen Mirroring icon.
10. Choose to Use As Seperate Display.
    
11. Your Mac’s screen will now be extended to your second monitor.
12. To scale your display, go to Apple > System Preferences > Displays.
    
13. On your second screen, a separate Displays window will open.
14. Here, choose your Resolution to be Scaled.
    
15. Now, select the optimal resolution for your second screen.
16. When you get a prompt message, click Yes to scale your display.

Problem Detecting the Second Screen?

When you connect the second screen and your Mac does not recognize it automatically, restart your computer and try again. If this does not do much, you can force your computer to detect the connected displays.

1. Plug in your second screen.
2. Then, open Finder.
3. Go to Apple > System Preferences from the menu bar.
   
4. Click on Displays.
5. Then, hold Option on your keyboard and select the option to Detect Displays.
   
6. Your system will now scan for nearby/connected displays.
7. When it detects the compatible display, it’ll automatically connect the second screen.