More Screen Space for $0
A second monitor changes how you work. Email on one screen, your main task on the other. Reference material beside your document. Slack visible without alt-tabbing.
A decent standalone monitor costs $150-300. Your old iPad, with the right app, does the same job for free. Apple even built this directly into macOS. And if you’re on Windows or have an older iPad, there are solid third-party options too.
Option 1: Sidecar (Mac + iPad) — Free, Built In
If you have a Mac and a reasonably modern iPad, Sidecar is the answer. It’s built into macOS and iPadOS, it’s free, and it just works.
Requirements:
- Mac running macOS Catalina (10.15) or later
- iPad running iPadOS 13 or later
- Both signed in to the same Apple ID
- Both on the same Wi-Fi network (or connected via USB cable)
Supported iPads:
- iPad Pro (all models)
- iPad Air (3rd gen / 2019 and newer)
- iPad (6th gen / 2018 and newer)
- iPad mini (5th gen / 2019 and newer)
How to set it up:
- On your Mac, click the Control Center icon in the menu bar (or go to System Settings → Displays)
- Click Screen Mirroring
- Select your iPad
- Choose “Use as Separate Display” (not “Mirror”)
That’s it. Your iPad is now a second monitor. Drag windows to it, adjust the arrangement in Display settings, and work.
What about older iPads? If your iPad is too old for Sidecar (iPad Air 2, iPad mini 4, or anything earlier), skip to Option 2 or 3 below. Those work with older devices.
Option 2: Duet Display — $4/year (or One-Time Purchase on Older Versions)
Duet Display is the best third-party option and works with older iPads and Android tablets that Sidecar doesn’t support. It also works with Windows PCs.
Requirements:
- iPad running iOS 12+ or Android tablet running Android 8+
- Mac or Windows PC
- Duet Display app on the tablet ($4/year) plus the free companion app on your computer
- USB cable or Wi-Fi connection
Setup:
- Download Duet Display from the App Store or Google Play
- Download the Duet companion app on your Mac or PC (duetdisplay.com)
- Connect via USB cable (most reliable) or Wi-Fi
- Your tablet appears as a second display
Why Duet over free alternatives: Lower latency, better color accuracy, and it supports touch input — you can tap and interact with your computer through the tablet screen. It was built by former Apple engineers and it shows.
The old pricing situation: Duet used to be a one-time $10 purchase. They moved to subscription pricing at $4/year. If you bought it years ago, your old license may still work on an older iPad. Worth checking before re-purchasing.
Option 3: Spacedesk (Windows + Any Tablet) — Free
If you’re on Windows and don’t want to pay for Duet, Spacedesk is a solid free alternative.
Requirements:
- Windows 10 or 11 PC
- Any iPad or Android tablet with a web browser (or the Spacedesk app)
- Same Wi-Fi network
Setup:
- Install the Spacedesk Driver on your Windows PC (spacedesk.net)
- On your tablet, either open the Spacedesk app or navigate to your PC’s IP address in the browser
- The tablet connects as a second display
Trade-offs: There’s slightly more latency than Duet, and the initial setup is less polished. But it’s genuinely free with no limitations, and it works with very old tablets that can run a web browser.
Option 4: Deskreen (Any Computer + Any Tablet) — Free, Open Source
Deskreen turns any device with a web browser into a second screen for any computer. Mac, Windows, Linux — doesn’t matter.
Setup:
- Download Deskreen on your computer (deskreen.com)
- Open a browser on your tablet
- Scan the QR code or enter the URL that Deskreen provides
- Choose to extend or mirror your display
It’s free, open source, and works with literally any tablet that has a browser. The latency is higher than the other options, so it’s better for static content (documents, chat, reference material) than for video or fast-moving visuals.
Which Option Should You Pick?
| Situation | Best Option | Cost |
|---|---|---|
| Mac + newer iPad (2018+) | Sidecar | Free |
| Mac + older iPad or Android tablet | Duet Display | $4/yr |
| Windows PC + any tablet | Spacedesk | Free |
| Any computer + any tablet | Deskreen | Free |
| Want the lowest latency | Sidecar or Duet | — |
| Want touch input on the tablet | Duet Display | $4/yr |
Getting the Most Out of Your Second Screen
Once you have the second display working, a few tips to make it actually useful:
What to Put on the Tablet Screen
- Email or Slack — keep communication visible without it stealing your main screen
- Reference material — documentation, specs, PDFs, the spreadsheet you’re cross-checking
- Music or podcast controls — Spotify on the tablet, work on the main screen
- Video calls — put the call on the tablet, your work on the main display
- Calendar — keep your schedule visible all day
Arrange Your Displays
In your display settings (System Settings → Displays on Mac, Settings → Display on Windows), drag the tablet display to match its physical position. If the iPad is to the right of your laptop, put it to the right in settings. This makes dragging windows between screens feel natural.
Use a Stand
If the iPad is lying flat on the desk, you’ll be looking down at it — not great for your neck. A simple tablet stand ($12) at eye level next to your laptop makes a huge difference. The Lamicall adjustable stand works well for this.
Wired vs. Wireless
USB cable gives you less latency and doesn’t depend on your Wi-Fi being stable. If you’re doing anything where speed matters (design work, coding with fast scrolling), use the cable. For static content like email or documents, wireless is fine.
What About Using the iPad as a Drawing Tablet?
If you have an Apple Pencil-compatible iPad and Sidecar, yes — you can use it as a drawing tablet for your Mac. Sidecar supports Apple Pencil input, which means your iPad becomes a Wacom-style drawing surface for Photoshop, Illustrator, Procreate (native), or any Mac app.
For older iPads without Pencil support, Duet Display supports basic stylus input, but it’s not as precise.
Performance on Old Tablets
The honest answer: it depends on the app.
Sidecar on supported iPads: Smooth. Apple optimized this well. Even an iPad 6th gen (2018) handles it without lag.
Duet on older iPads (iPad Air 1, iPad mini 2): Works, but there’s noticeable lag when scrolling quickly or moving windows. Fine for email, documents, and chat. Not great for video or design work.
Spacedesk and Deskreen on old tablets: Similar story. Static content is fine. Fast motion shows artifacts and delay.
So: if you mostly need a second screen to glance at things (Slack, email, reference docs), any old tablet works well. If you need to click around and interact with it constantly, you want a newer iPad with Sidecar or Duet over USB.
Quick Setup Checklist
- Check your devices against the requirements above
- Pick the right option for your combination
- Install the software on both devices
- Connect via cable or Wi-Fi
- Arrange displays in your settings
- Put the tablet on a stand at eye level
- Drag a window over — you now have two screens
Total time: 5-10 minutes. Total cost: $0-4.
Five minutes of setup. 50% more screen space. And that old iPad finally has a daily job again.
