The tablet in your drawer is already a monitor. A second-generation iPad Air has a Retina display, USB-C or Lightning to charge, and a Bluetooth stack that pairs with your Mac in seconds. Buying another 13-inch monitor at that spec would run north of a hundred dollars. Turning your iPad into one costs somewhere between nothing and $30.
We tested seven apps that turn an iPad into a second display for Windows and macOS. Wired, wireless, native, cross-platform, free, subscription. We judged each one on latency, resolution options, how quickly it reconnects after sleep, and whether it treats the iPad as a first-class monitor (drag windows freely) or a mirror.
What to look for in an iPad-as-second-monitor app
- Wired vs wireless. Wired is lower latency and no jitter; wireless is cable-free but competes for Wi-Fi bandwidth.
- Extended vs mirror. Extended lets you drag arbitrary windows to the iPad; mirror just repeats the main display.
- Retina scaling. iPads have dense screens. If the app forces 1x, text looks sharp but tiny.
- Touch and Pencil. Some apps pass through touch and Apple Pencil pressure so the iPad becomes a Wacom stand-in.
- Reconnect behavior. After the Mac or iPad sleeps, does the second display come back automatically or do you re-launch?
- Platform. macOS-only, Windows-only, or both matters if you use both.
Quick comparison
| App | Best for | Platforms | Free plan | Starting price | Rating |
|---|---|---|---|---|---|
| Sidecar | macOS + iPad users | macOS + iPadOS | Built-in, free | Free | 4.5 (App Store) |
| Duet Display | Cross-platform wired reliability | Win, macOS + iPadOS | Trial only | Around $3.99/mo Air | 4.3 |
| Astropad Studio | Digital artists using Pencil | macOS + iPadOS | Trial | Around $79.99/yr Studio | 4.4 |
| Luna Display | Zero-lag wireless with a dongle | Win, macOS + iPadOS | None (hardware) | One-time around $129 | 4.2 |
| spacedesk | Free wireless Windows setup | Windows + iPadOS/Android | Fully free | Free | 4.1 |
| Splashtop Wired XDisplay | Wired Windows on a budget | Windows + iPadOS/Android | Free | Free (paid Pro tier) | 4.0 |
| Yam Display | Wired macOS with low overhead | macOS + iPadOS | Trial | Around $9.99 one-time | 4.2 |
The apps
1. Sidecar, best for macOS + iPad users
Sidecar is Apple’s own answer, and if your Mac and iPad are both from the last several years, it’s the fastest install: turn it on in Control Center. Wireless works within about ten meters; a USB-C or Lightning cable pins it to zero-flake reliability. Full Apple Pencil support, Touch Bar overlay for Macs without one, sidebar with modifier keys.
Sidecar for extending is the “just works” pick when both devices are Apple’s. There’s no monthly fee, no third-party account, and reconnect after sleep is normally seamless.
Where it falls short: Requires reasonably modern hardware on both sides. macOS only (Windows users can stop reading this entry). Some third-party apps handle Pencil pressure less cleanly than in Astropad.
Pricing:
- Free (part of macOS)
Platforms: macOS, iPadOS
Download: Built into macOS. Enable via Control Center → Screen Mirroring.
Bottom line: The right pick when you’re in the Apple stack and don’t want to install anything.
2. Duet Display, best cross-platform wired reliability
Duet Display started as the wired iPad-to-Mac tool of choice and has broadened. It runs on Windows and macOS, connects over USB or wireless, and its paid Air and Pro tiers add features Sidecar doesn’t (higher framerates, remote desktop-style access, air mode over Wi-Fi with color accuracy).
Duet for extending is the reliable cross-platform pick. Wired mode reliably delivers a stable 60 fps. Reconnect after sleep is fast; the Menu Bar/System Tray app remembers your setup.
Where it falls short: Now subscription-first. The one-time purchase most users remember is not the current pricing model; expect a monthly or annual bill for the tiers with air mode and higher framerates.
Pricing:
- Free trial
- Around $3.99/mo Duet Air
- Higher tier for remote desktop-style access
- Annual pricing brings the monthly down
Platforms: Windows, macOS, iPadOS
Download: duetdisplay.com
Bottom line: The right pick when you’re on Windows or need a wired setup that works the same on both OSes.
3. Astropad Studio, best for digital artists using Pencil
Astropad Studio is the pick when the iPad-as-second-monitor question is really “can I use it as a Wacom Cintiq for Photoshop or Procreate on desktop.” Studio’s LIQUID engine tunes for the drawing-latency problem specifically; pressure and tilt from Apple Pencil map into the desktop app.
Astropad Studio for artists means low input latency on pen strokes, custom shortcut sidebars per app, and gesture mapping that a general-purpose display app doesn’t do.
Where it falls short: Studio is a subscription in the “creative pro tool” price bracket, not the “iPad-as-screen” one. Astropad Standard exists as a cheaper one-time buy but drops the low-latency drawing engine.
Pricing:
- Trial
- Around $79.99/year Astropad Studio
- Astropad Standard is a one-time purchase for lighter use
Platforms: macOS, iPadOS (Windows via a separate Astropad product line)
Download: astropad.com
Bottom line: The right pick when the second display is really a drawing tablet in disguise.
4. Luna Display, best zero-lag wireless with a dongle
Luna Display is the hardware-plus-software combo from the Astropad team. Plug the small USB-C or Mini DisplayPort dongle into the host, and the iPad becomes a real second display over Wi-Fi with the responsiveness of a wired connection.
Luna Display for wireless means near-zero perceived lag, easy switch between iPads or Macs, and full extended-desktop behavior including HiDPI.
Where it falls short: Costs money up front and requires an extra USB port on the host. The dongle is an easy thing to lose.
Pricing:
- One-time around $129 for the dongle
- No subscription
Platforms: Windows, macOS, iPadOS
Download: lunadisplay.com
Bottom line: The right pick when you want wireless without the compromises and are willing to pay once.
5. spacedesk, best free wireless Windows setup
spacedesk is the entry that runs $0 and still works well. Install the Windows server on your PC, install the iPad viewer, and both devices connect over the local network. Extended mode, mirror mode, multi-client (many spare screens at once), and adjustable image quality.
spacedesk for extending is the free-forever option most Windows users don’t know exists. It’s how you turn an iPad, an old Android tablet, and a Fire tablet into three extra monitors without touching a wallet.
Where it falls short: Wi-Fi only (no USB). Image quality is user-tunable but at highest fidelity, refresh drops. macOS is not supported as a host.
Pricing:
- Fully free
- No paid tier
Platforms: Windows (host), iPadOS, Android, Windows client
Download: spacedesk.net
Bottom line: The right pick on Windows when the budget is zero.
6. Splashtop Wired XDisplay, best wired Windows on a budget
Splashtop Wired XDisplay covers the “I want wired on Windows without paying Duet” case. Install both apps, plug in USB, and the iPad shows up as an extended display. Lower framerates than Duet’s paid tiers but zero cost and zero Wi-Fi contention.
Splashtop for wired on Windows means the low-fuss free option that’s still cable-based. Battery on the iPad also charges while connected.
Where it falls short: The free tier is capped at a modest frame rate. Splashtop’s push toward its paid remote-desktop products means the free XDisplay app doesn’t get frequent updates.
Pricing:
- Free tier
- Paid Splashtop tiers add other Splashtop products, not extra XDisplay features
Platforms: Windows, iPadOS, Android (macOS host support is limited)
Download: splashtop.com/wiredxdisplay
Bottom line: The right pick on Windows when wired is important and paying isn’t.
7. Yam Display, best wired macOS with low overhead
Yam Display is the quieter macOS pick, a one-time purchase that turns any iPad into a wired second display with minimal CPU overhead on the Mac side. Retina scaling, touch and Pencil support, and a tiny memory footprint.
Yam for macOS extending is the “I want Sidecar-style behavior on an older Mac Sidecar refuses to run on” pick. It’s also handy on Sidecar-capable Macs when you’d rather not run Apple’s stack.
Where it falls short: Wired only. macOS host only (iPad client). Not as feature-rich as Duet; no air mode.
Pricing:
- Around $9.99 one-time (App Store)
- No subscription
Platforms: macOS, iPadOS
Download: App Store
Bottom line: The right pick on macOS when Sidecar refuses to run and you want to pay once.
How to pick
If your Mac and iPad both support Sidecar, use Sidecar. Free, built in, works.
If you’re on Windows and want wireless free, use spacedesk. If you want wired free, use Splashtop Wired XDisplay.
If you’re on Windows or cross-platform and want the polished wired experience with all the tiers, use Duet Display. Budget for the subscription.
If you’re on macOS and Sidecar won’t run on your hardware, use Yam Display for wired at low cost.
If you want wireless with wired feel across Windows and macOS and don’t mind a hardware dongle, use Luna Display.
If the iPad is really a drawing tablet, use Astropad Studio.
FAQ
Can I use an old iPad as a second monitor for free? Yes. On macOS Sidecar is free and built in. On Windows spacedesk is free and works over Wi-Fi. Splashtop Wired XDisplay is a free wired option on Windows.
Which iPad-as-monitor app has the lowest latency? Wired connections beat wireless every time. Sidecar wired, Duet wired, Astropad Studio wired, and Luna Display (via its dongle) all deliver near-zero perceived lag.
Does Sidecar work with Windows? No. Sidecar is macOS + iPadOS only. On Windows use Duet, spacedesk, Splashtop, or Luna Display.
Can I use the iPad’s touchscreen with a Windows PC? Yes with spacedesk, Duet, and Splashtop. All three pass touch back to the host. Apple Pencil pressure varies by app.
Do these apps use Wi-Fi or Bluetooth? Wireless options run over Wi-Fi, not Bluetooth. Both devices should be on the same network for anything wireless to work. Wired options run over USB and don’t touch the network.
Will this drain the iPad battery? Wired connections charge the iPad while it’s in use. Wireless drains normally; plug in for long sessions.
