1. Computer Skills

How to Connect an iPad as an Additional Screen on a Mac

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Read Time: 5 min

One of the downsides to working from solely a Mac is the lack of screen real estate. Even with a 15” MacBook Pro, the screen is a good deal smaller than an iMac. You can add an external screen but this detracts from a notebook’s big advantage: portability. 

Recently, though, I’ve been trying something different. 

When I travel I also bring an iPad. It’s great for watching films on the plane without needing the tray table or running out of battery too quickly. Or both. An iPad can also be used as a second screen for a Mac. Here’s how.

Duet Display

Duet Display is an app that turns an iOS device into an external display for a Mac. There are two parts to it: 

  1. the Duet Display iOS app, and 
  2. the Duet Display Mac app

While the Mac app is free and available from Duet’s website, the iOS app costs £19.99/$19.99 in the App Store. There is also a Windows app if you want to use an iOS device as a screen for a PC.

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My screen setup with a 15" MacBook Pro and iPad Mini 2. Impressive isn't it!

Although the Duet app will work with any iOS device, in reality it’s best used with an iPad. Even an iPhone 7 Plus doesn’t have a big enough screen to be much use as an external monitor. 

Duet makes a big deal of the fact it was designed by ex-Apple engineers, and the polish shows. It only works when the iPad is connected to the Mac through a lightning cable rather than with a laggy wifi interface. 

Setting Up Duet Display

Download Duet from the developer’s website on the Mac and install it. You’ll need to enter the admin password and restart the Mac for the installation to take effect. Also download the Duet iOS app from the App Store on the iPad. 

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Duet is super simple to setup. 

Open Duet on the iPad and connect it to the Mac using the appropriate USB cable. Duet will work over both Lightning and 30-Pin connections. 

And just like that, the iPad will be up and running as an extra screen for the Mac. 

Configuring Duet Display

While Duet will work right out of the box, to get the best results you need to tweak a few things. You want what you’re seeing on the iPad to roughly match how everything appears on the Mac. 

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To get the most from Duet, you need to select the options that work for you. 

When you first start Duet, it will mirror the screen on the Mac. This is useful in a few circumstances—like letting clients look at photos as you edit them on a photoshoot—but in most cases, you want Duet to work as a second screen.

Click on the Duet menubar icon and select one of the options under Extend Display. There are four to choose from: 

  1. Regular Resolution (Energy Efficient)
  2. iPad Pro Resolution
  3. Retina Resolution (High Power), and 
  4. High Resolution (Smaller Text)

I’ve found that Retina Resolution works best for how I have my display set up, but try all four options to see what works for you.

There are two other options that control how the display will appear: Framerate and Pixel Quality. Each has a High Power and Energy Efficient option. If you are running on battery power or using a relatively underpowered Mac, go with the Energy Efficient options. Otherwise you’re better off just setting things to High Power

You can also use Duet to add a Touch Bar to any Mac. Just select Touch Bar Enabled from the menubar. 

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You can arrange how Duet positions the displays. 

To change the layout of your multiple screens, go to System Preferences > Displays > Arrangement. You’ll see all the screens you currently have connected to the Mac and you can position them how you please. I like to have the iPad sit to the right of the main display. 

Using Duet Display

iPads obviously have an awesome touch screen and it would be silly if you weren’t able to make use of it. The good news is with Duet you’re able to. You can drag with one finger to move the mouse curser about, drag with two fingers to scroll, and tap to click. 

If you have an iPad Pro you can also subscribe to Duet Pro. The big feature is that you can then use the iPad and an Apple Pencil as a pressure sensitive drawing tablet for the Mac. This means you can use it to sketch or edit photos in Photoshop. Duet Pro is a $19.99 a year in-app subscription.

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The Mountie clip has made a huge difference. 

I first tried Duet when it launched a few years ago and, while I was impressed, I didn’t use it a lot. It was just too awkward to prop the iPad up somewhere. 

Things changed when I discovered Ten One Design’s Mountie. This small clip mounts the iPad to the Mac’s display. It’s adaptable enough to work with any iOS device. At $20 it’s not cheap, but it’s made all the difference to my workflow. 


Duet is one of those apps that, once you start using it, you won’t know how you did without. I mainly use my iPad to keep an extra browser open for referencing things, but you can use it for anything. If you like having a lot of screen real estate but need the portability of a MacBook, Duet is worth a look. 

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