If there's one thing that's better than the Retina display on your MacBook or iMac, it's plugging in a second screen. That's all very well if you have a spare screen, or the cash for an additional display, but what if you don't? Can you use your iPad as a second monitor? The answer is, yes you can.

It's actually been something you can do via third-party software for some time, but Apple's finally making it possible to do so via macOS Catalina. In this article, we'll look at what you'll need to use your iPad as a second screen for your Mac in Catalina, and also how you can use your iPad as a second screen if you're not running Apple's latest operating system.

Sidecar in macOS Catalina

In macOS Catalina, now available following an October 2019 release, you're able to use your iPad as a second screen for your Mac, either mirroring it or extending your display so that you can fit in even more windows. You can choose to plug the iPad directly into the Mac or connect it wirelessly using Bluetooth and Continuity (within a range of 10 meters).

iPad sidecar

What you need:

  • A compatible Mac running macOS Catalina - most Macs since 2012 can run Catalina but not all Macs will work with Sidecar., see below for a full list. 
  • An iPad running iPadOS 13 (see below for a full list)
  • It is necessary to be logged into the same iCloud account on the Mac and iPad.
  • You’ll need to be within 10 meters of your Mac if you're connecting wirelessly.

iPads that work with Sidecar include:

  • 12.9-inch iPad Pro
  • 11-inch iPad Pro
  • 10.5-inch iPad Pro
  • 9.7-inch iPad Pro
  • iPad (6th generation)
  • iPad (5th generation)
  • iPad mini (5th generation)
  • iPad mini 4
  • iPad Air (3rd generation)
  • iPad Air 2

Macs that work with Sidecar include:

  • MacBook Pro (2016 or later)
  • MacBook (2016 or later)
  • MacBook Air (2018 or later)
  • iMac (2016 or later, as well as iMac 5K, 27-inch, late 2015)
  • iMac Pro
  • Mac mini (2018 or later)
  • Mac Pro (2019, when it launches)

How to use an iPad as a second screen on macOS Catalina

If you've got a compatible Mac and iPad, setting up the second display functionality is, in true Apple form, fairly straightforward:

  1. You can connect your iPad using your charging cable (if you have the required ports on your Mac), alternatively, you can connect via Bluetooth as long as you are within 10 meters of the Mac. There's not much of a difference in terms of delay, but you might find your iPad lasts a little longer if plugged in.
  2. To connect, click on the AirPlay icon in the menu at the top right of your screen. (It’s a square with a triangle).
  3. You should see your iPad listed. Select it and an an extension of your Mac’s screen will appear on the iPad display.
  4. If you would prefer to mirror your Mac’s screen on the iPad, rather than use the iPad as an extension of your workspace, click on the new screen icon that has appeared in the status bar (it should have replaced the AirPlay icon).
  5. Switch from "Use as Separate Display" to "Mirror Built-in Retina Display".
  6. You can also connect to your iPad via the Sidecar section in System Preferences.

Other features of Sidecar

There's much more to Sidecar than simply extending your workspace. Other features include:

  • A virtual Touch Bar displayed on the iPad, bringing many of the Touch Bar features that are currently exclusive to the MacBook Pro to other Macs.
  • While it doesn't accept touch input, you can use an Apple Pencil and turn your iPad into a graphics tablet. (See below to see which iPads will work with the feature).

The following iPads can be used as graphics tablets (with Apple Pencil) in macOS Catalina:

  • 12.9in iPad Pro
  • 11in iPad Pro
  • 10.5in iPad Pro
  • 9.7in iPad Pro

How to use an iPad as a second display on older Macs

But what if you have a Mac that doesn't support macOS Catalina? There a handful of third-party tools that allow you to use your iPad as a monitor for your Mac, but unlike Apple's built-in option, these are paid-for apps.

What you'll need

  • A Lightning to USB cable
  • An iPad
  • Software such as Duet Display, iDisplay and AirDisplay.
  • A Mac running macOS 10.13.3 or earlier - unfortunately, 10.13.4 broke some of the DisplayLink functionality that these apps rely on.

Problems

These apps use DisplayLink USB graphics technology, which can be used to connect computers and displays via USB, Ethernet, and WiFi. Unfortunately, macOS 10.13.4 broke DisplayLink - and therefore apps like Duet Display and those mentioned above may not work if you have installed the update to High Sierra.

The issue was fixed with the release of macOS Mojave 10.14.2, so if you're currently running High Sierra 10.13.4, try and upgrade your OS.

How to use Duet Display

In this example, we're using Duet Display, which was developed by a team of ex-Apple engineers. Duet Display allows you to use the tablet as a second display not just on your Mac, but a PC too.

Duet Display also provides limited touchscreen support, allowing you to tap and swipe your way around macOS. It means you don’t have to spend your time moving your mouse between the two screens, which becomes especially laborious when using a trackpad and again, enables users to be more productive.

We'll show you how to set up Duet display to use your iPad (or any other iPad or iPhone) as a second display for your Mac or PC.

Here’s an overview of how to use your iPad Pro as a second display using Duet Display, with more in-depth instructions below:

  1. On your iPad, open the App Store and install Duet Display– at the time of writing, it costs £9.99/$9.99. It’s a universal app, so it’ll also be available for use with your iPhone.
  2. On your Mac or PC, head over to the Duet Display website and download the Duet for Mac/Windows app.
  3. Install the Duet companion app for Mac or PC. This is an important step, as the companion app allows your iPad and Mac to ‘talk’ to each other. Follow the installation instructions, and restart your Mac to complete the installation.
  4. On your iPad, open the Duet Display app and plug it into your Mac or PC using a Lightning cable (or 30-pin cable if you’re using an older iPad).
  5. The iPad should be recognised by the Duet companion app, and your desktop should now extend across the two displays. You’re then ready to go! Quality settings can be tweaked via the Duet companion app on your Mac or PC to provide higher graphics, smoother refresh rates, etc. and to disconnect the display, simply close the app on your iPad.

If you are using your Mac with an external screen and want to close the lid on your MacBook, here's how to use MacBook with the lid closed, and For more Mac tips, take a look at our top Mac tips, tricks and timesavers.