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

Discussion in 'Mac Blog Discussion' started by MacRumors, Dec 6, 2018.

  1. MacRumors macrumors bot


    Apr 12, 2001

    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.

    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 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
  2. DrJohnnyN Suspended


    Jan 27, 2010
  3. Romeo_Nightfall macrumors regular


    Aug 8, 2018
    i have this app, but never use it.
    does actually anyone really use it?
  4. goomba478 macrumors regular

    May 10, 2012
    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!
  5. arrowood macrumors newbie

    Jan 24, 2018
    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.
  6. maninhat macrumors newbie

    Sep 28, 2012
    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
  7. skillz1318 macrumors regular

    Mar 21, 2006
    Use it as well any time I'm remote; love dual monitors (Win 10 and iPad Pro 2018)
  8. 4jasontv macrumors 65816

    Jul 31, 2011
    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?
  9. johnnybeagle macrumors member


    Jun 7, 2017
    I use Luna occasionally

    I've been very happy with it
  10. TMRJIJ macrumors 68030


    Dec 12, 2011
    South Carolina, United States
    Haven’t really gotten the chance to make use of this app yet. Maybe it’s time to change that
  11. Fender2112 macrumors 65816


    Aug 11, 2002
    Charlotte, NC
    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.
  12. MacDonaldTrump macrumors regular


    Nov 28, 2018
    Brisbane Australia
    I use it as second display photo editing works well.
  13. shareef777 macrumors 68020


    Jul 26, 2005
    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).
  14. RedGala macrumors regular


    Jun 17, 2015
    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.
  15. dguisinger macrumors 6502

    Jul 25, 2002
    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.
  16. RedGala macrumors regular


    Jun 17, 2015
    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.
  17. max.ine macrumors regular


    Aug 16, 2016
    I want to cry when I imagine the latency...
  18. shareef777 macrumors 68020


    Jul 26, 2005
    Chicago, IL
    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".
  19. LIVEFRMNYC macrumors 604

    Oct 27, 2009
    Don't know why they haven't enabled this on Airplay. It could be an option easily added.
  20. skillz1318 macrumors regular

    Mar 21, 2006
    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.
  21. mrow macrumors regular

    Aug 15, 2009
    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.
  22. bullamakanka macrumors newbie

    Apr 2, 2014
    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.
  23. mrow macrumors regular

    Aug 15, 2009
    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.
  24. ignatius345 macrumors 68000

    Aug 20, 2015
    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.
    --- Post Merged, Dec 6, 2018 ---
    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...
  25. brdeveloper macrumors 68020


    Apr 21, 2010
    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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