How to Use Your iPad as a Second Screen for Your Mac

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Duet Display is an app made by former Apple engineers that allows you to use your iPad as a second screen for your Mac. In this article, we'll explain how it works and the steps you need to follow to get things up and running.


Duet Display is a great way to extend your Mac's desktop and can come in especially handy when you're working away from home and want to broaden your productivity space, but don't have the luxury of a dedicated external monitor.

In earlier versions of macOS, the app was hampered by changes to Apple's operating system that caused its developers no end of problems, but the latest Duet update (v2.0.3.8+) released on December 5 appears to have resolved those issues thanks to the introduction of full hardware acceleration support.

We are excited to announce a breakthrough. As of macOS 10.14.2+ & duet v2.0.3.8+, Duet Display is now fully hardware accelerated, making the fastest way to turn your iPad into a second display even faster. 100% free update at https://t.co/VxaXUTgXdb pic.twitter.com/FbbuqAGF1E - Duet Display (@duetdisplay) December 5, 2018

Duet Display is actually one of two apps best known for letting users leverage their iPad as a second screen for their Mac. The other is Luna Display ($79.99), but that app uses another implementation that requires two small dongles to ensure a consistent low-latency connection.

Duet Display on the other hand is a pure software solution and a lot more affordable at $9.99, which is why we've chosen to cover it here.

How to Use Your iPad as a Second Screen for Your Mac
  1. Launch the App Store on your iPhone or iPad and download Duet Display ($9.99).

    Open a browser on your Mac, navigate to www.duetdisplay.com and click the Download Mac button at the top of the webpage to download the free Mac client.
  2. Once the Duet client app is downloaded to your Mac, drag it from the Downloads folder to the Applications folder.

    Double-click the Duet Mac client to launch it.
    Connect your iPhone or iPad to a free USB-A port on your Mac using a Lightning cable. (If you're using a Mac that has the newer USB-C ports, you'll need to use a Lightning to USB-C cable, which Apple sells in 1-meter and 2-meter lengths.)

    Launch the Duet app on your iPhone or iPad and wait a moment while it communicates with the Duet Mac client. You should see your Mac's desktop mirrored or extended on your iPad screen once a successful connection is made.
Once you've got things working, it's worth checking out Duet's display options: click the Duet applet in your Mac's menu bar and if you have an iPad connected you'll see a button to enable a touch-sensitive MacBook Pro-style Touch Bar along the bottom of your iPad's screen.


If you click Advanced Settings, you can choose from a number of Display options to scale the output to your iOS device. The pre-defined resolutions allow you to see either larger text or more desktop space, and Duet helpfully recommends which scale to pick based on device model.


Check the box next to Mirror Display if you want to duplicate your Mac's desktop on your iPad rather than extend it. There are also options to enable Retina display mode, increase the framerate from 30 to 60fps, and switch the image quality from Regular to High, all of which require more device energy.

If you click the cog wheel in the Duet menu bar applet, you'll also find some additional settings worth attending to. If your Mac has a dedicated graphics card then you can set Duet to use it exclusively for faster performance, alternatively you can limit it to the integrated graphics for energy efficiency.

There are also menus to enable or reduce transparency on your iOS device display, an option to start Duet at login, and a link to change the Display Arrangement of your screens in System Preferences.

iPad showing as external display in System Preferences

If you get on with Duet Display, there are Air ($19.99 annually) and Pro ($24.99) versions that offer additional features like wireless connectivity and Apple Pencil support, respectively. For more information and support, check out the Duet Display website.

Article Link: How to Use Your iPad as a Second Screen for Your Mac
 

goomba478

macrumors regular
May 10, 2012
176
113
Luna Display needs only one plugged in accessory (they have two versions for either USB-C or Display port) and also can work wirelessly or wired. It also allows full support with Apple Pencil. Works great!
 
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maninhat

macrumors newbie
Sep 28, 2012
17
28
I bought duet display a while back, tried again a couple of weeks ago. It's slow, it crashes and has to be reconnected all the time. Wasted money.

Tested on Macbook Pro 15 from 2017 and iPad pro from 2017 as well
 

4jasontv

macrumors 68000
Jul 31, 2011
1,885
1,642
Every time I telecommute or work outside of my office. Used it yesterday, all day, in fact. For a dual-monitor addict like me, it's a godsend.
How is it better than just pulling up the document on your iPad and using cloud storage and Universal Clipboard? What do you use it for where the lag doesn’t drive you crazy?
 

shareef777

Suspended
Jul 26, 2005
2,445
3,218
Chicago, IL
Forgot I bought this app with an iPad I had a few years back. It was laggy/buggy and never liked it and so stopped using it. Started using it now with my 11" Pro and it's significantly better. Will see how reliable it is. Only odd thing is it says it's updated for the new pros, but I still see black vertical bars when connected as a second display (though no black bars when dis-connected).
 

RedGala

macrumors regular
Jun 17, 2015
199
826
WARNING: Duet display is actually a terrible app. They give you sub-par resolution and latency, only to ask you for an annual fee for an actually acceptable mirroring/extension experience.

If the fact that they STILL haven’t updated their app for the new iPad Pro isn’t a sign that they suck, then I don’t know what is. I’m so mad that I wasted $10 and I hope their theft bites them in the future.
 
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dguisinger

macrumors 6502a
Jul 25, 2002
506
277
I use an Asus USB-C 15" mobile screen.... it was like $250.

I wouldn't want to run a monitor on something that uses a remote software hack, i'd rather have the OS natively recognize it, use the USB C / DisplayPort protocol, and a screen that can natively display it.

I've said for a while, I wish the new iPad Pro's supported it natively, would have given me a reason to buy one. With all that custom silicon you would think they could have done it.
 

RedGala

macrumors regular
Jun 17, 2015
199
826
I use an Asus USB-C 15" mobile screen.... it was like $250.

I wouldn't want to run a monitor on something that uses a remote software hack, i'd rather have the OS natively recognize it, use the USB C / DisplayPort protocol, and a screen that can natively display it.

I've said for a while, I wish the new iPad Pro's supported it natively, would have given me a reason to buy one. With all that custom silicon you would think they could have done it.
Exactly what I’ve been thinking. With the thousands of engineers Apple has, you’d think they could muster the courage to support native display extension. I hope they read these comments and learn.
 
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shareef777

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Jul 26, 2005
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How is it better than just pulling up the document on your iPad and using cloud storage and Universal Clipboard? What do you use it for where the lag doesn’t drive you crazy?
Which iPad are you using it with? I have the 2018 11" and there's no lag at all. I have Slack and Microsoft Code running at full screen on the iPad and it's awesome to be able to use the same keyboard/trackpad to control my iPad screen. It's a more natural workflow then switching between input devices on my MBP and those on my iPad.

Another weird issue is that I get an "Apple Watch is unable to unlock your computer while your screen is shared".
 

LIVEFRMNYC

macrumors 604
Oct 27, 2009
7,443
8,631
I've said for a while, I wish the new iPad Pro's supported it natively, would have given me a reason to buy one. With all that custom silicon you would think they could have done it.
Don't know why they haven't enabled this on Airplay. It could be an option easily added.
 

skillz1318

macrumors regular
Mar 21, 2006
234
10
I haven't noticed any real latency issues via USB-C, but I am using it for Office apps and not gaming. I would obviously expect latency via wifi.
 

mrow

macrumors 6502
Aug 15, 2009
322
389
I use an Asus USB-C 15" mobile screen.... it was like $250.

I wouldn't want to run a monitor on something that uses a remote software hack, i'd rather have the OS natively recognize it, use the USB C / DisplayPort protocol, and a screen that can natively display it.

I've said for a while, I wish the new iPad Pro's supported it natively, would have given me a reason to buy one. With all that custom silicon you would think they could have done it.
Obviously a real, dedicated display would be the best solution. But for people who sometimes need a mobile external display and already own an iPad this solution is significantly cheaper and after this update it works great, and uses hardware acceleration so you're not wasting CPU cycles to power it.
 

bullamakanka

macrumors newbie
Apr 2, 2014
14
7
i have this app, but never use it.
does actually anyone really use it?
Yes, both as a third monitor/Photoshop tablet when at home, and as a primary monitor when on the road. I have a Mac Mini late-2012 i7/16Gb/500gb SSD/4Tb (all internal), the iPad Pro 12.9” monitor setup works perfectly. No lag. I can get started up at a Starbucks in 30 seconds. The only drawback is needing a power outlet, otherwise it’s perfect. I bring my extended keyboard and Bluetooth mouse along, tune in to my phone’s Hotspot (often faster than the local WiFi offerings). This has been my remote setup for close to two years now.
 

mrow

macrumors 6502
Aug 15, 2009
322
389
WARNING: Duet display is actually a terrible app. They give you sub-par resolution and latency, only to ask you for an annual fee for an actually acceptable mirroring/extension experience.

If the fact that they STILL haven’t updated their app for the new iPad Pro isn’t a sign that they suck, then I don’t know what is. I’m so mad that I wasted $10 and I hope their theft bites them in the future.
When was the last time you tried it? The app has been broken for a while now and required a workaround that made it pretty much unusable. After this update those issues have been fixed and it works like it used to. I'd suggest giving it another try. Also, that subscription is only for the version that supports wireless and remote desktop capabilities. If you just want to hook an iPad up and use it as an external display hooked up with a cable it's just the one time cost of the app.
 
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ignatius345

macrumors 68020
Aug 20, 2015
2,390
3,176
I have an iPad, i never use, sitting on my desk. I might give this a try. Though its an iPad mini, not very big.
I could see it being useful for some specific apps you want to run in their own little separate space. If I was doing a lot of Adobe CS stuff on one monitor, I'd consider making that second display the place to park those numerous control palattes.
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Don't know why they haven't enabled this on Airplay. It could be an option easily added.
You can extend your display through AirPlay if you go through Apple TV. Not appropriate for every situation, but useful if you want a group of people all looking at your computer screen without hovering behind you...
 

brdeveloper

macrumors 68030
Apr 21, 2010
2,514
175
Brasil
You're all blaming the app basing your judgement on previous versions, but does actually anyone tested the update from December, 5, that is, yesterday?
 
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