You can use another laptop as a second monitor without any cable: on the laptop that will be the screen, install the Wireless Display optional feature and open the Wireless Display app, then on your main PC press Windows + K, pick that laptop and press Windows + P > Extend. Both machines need Wi-Fi with Miracast support. If that fails, the free app spacedesk does the same job over your home network or a USB cable. Plugging an HDMI cable between two laptops won’t work, because laptop HDMI ports almost always send video out, not in.
Why doesn’t an HDMI cable between two laptops work?
Because the second laptop’s HDMI port is an output, just like the first one’s. Two outputs connected together show nothing. When a Latitude owner asked on Dell’s forum whether the laptop’s HDMI port could accept a signal, the answer was no: it’s output only, and a USB video capture device is what you’d need. Another Dell community thread turned up a few exceptions, such as some Alienware 17 and 18 models with HDMI input, but those are rare gaming machines.
So you have three real options: wireless projection built into Windows, an app such as spacedesk, or a capture card. They’re compared in the table further down.
Problems people run into
“My desktop has no Connect to a wireless display option”
This is the most common dead end. A Surface Pro 7 owner who wanted to use the tablet as a second screen for a desktop PC found the option simply missing on the desktop, which used Ethernet rather than Wi-Fi. Wireless projection needs Wi-Fi hardware on both ends. A desktop without a Wi-Fi card can’t send to the laptop this way, so spacedesk over your network cable is the better route there.
“This device doesn’t support receiving Miracast”
Seen in Settings > System > Projecting to this PC on the laptop you want as the screen. In a Microsoft Q&A thread with exactly this message, the person’s PC reported Miracast as available in DxDiag, yet Windows still refused. The replies blamed the wireless hardware or drivers and suggested an external adapter; no fix was confirmed. Updating the laptop’s Wi-Fi driver from the maker’s site is worth a try, but if the message stays, use spacedesk instead.
“The mouse won’t work on the projected screen”
Wireless projection sends a picture. In a thread about input on wireless displays, users reported that keyboard input sometimes worked but the mouse didn’t, and Microsoft’s reply pointed to third-party software for full control. For an extended desktop that’s fine, since you drive both screens with the main PC’s mouse anyway.
Method 1: Windows’ built-in Project to this PC
Free, wireless and already in Windows, so start here. Microsoft’s projection guide covers the setup on Windows 11.
On the laptop that will be the second monitor
- Open Settings > System > Projecting to this PC.
- Select Optional features, then View features, search for Wireless Display, tick it, then select Next and Install.
- Go back to Projecting to this PC and set the first option to Available everywhere (or Available everywhere on secure networks). Set Require PIN for pairing to Never if you’re at home and want fewer prompts.
- Search the taskbar for Wireless Display and open the app. It needs Windows 11 version 22H2 or later; on older versions the app is called Connect.
On your main PC or laptop
- Make sure both machines have Wi-Fi turned on and are on the same network.
- Press Windows + K (or open Settings > System > Display > Multiple displays > Connect to a wireless display).
- Select the other laptop’s name. Accept the request on the second laptop if it asks.
- Press Windows + P and choose Extend. Now you can drag windows across to the second laptop.
- To line the screens up, open Settings > System > Display, click Identify, drag the numbered boxes to match where the laptops sit on your desk, and click Apply.
If the second laptop doesn’t show up in the list, Microsoft’s checklist is short: Wi-Fi on, and the Wireless Display app installed and open on the receiving side. HP also points out that wireless links can be less stable than wired ones, so expect some lag. It’s fine for chat, notes and documents, poor for games or video editing.
Method 2: spacedesk (works over Wi-Fi, Ethernet or USB)
When Miracast refuses to cooperate, spacedesk from datronicsoft is the usual answer. You install a driver on the main Windows 10 or 11 PC and a viewer app on the second laptop, and the second laptop appears to Windows as an extra display. According to spacedesk, it connects over USB, Wi-Fi or a LAN cable, and the viewer runs on Windows, Android and iOS, plus any browser through its HTML5 viewer.
- On the main PC, download and install the spacedesk Driver from spacedesk.net.
- On the second laptop, install the spacedesk Viewer for Windows.
- Connect both to the same network, or link them with a cable.
- Open the Viewer. It should list the main PC; select it to connect.
- On the main PC, press Windows + P > Extend, and arrange the screens in Display settings.
The viewer is free for private, non-commercial use as of October 2026, per its licensing page. That license expires after a while and you then install a newer driver version; businesses pay for a commercial license.
Method 3: a USB capture card
A capture card takes HDMI in and shows it on the second laptop through a camera or capture app. It’s the only true cable option, and HP mentions it for setups that need proper resolution support and low latency. You connect the main laptop’s HDMI out to the capture card, plug the card into the second laptop’s USB port, and open the video in the capture software full screen. It’s a mirror of an external display, so it works with consoles and cameras as well as PCs. The downside is cost and a small delay, and you need the capture software running the whole time.
Which method should you pick?
| Method | Cost | Connection | Best for | Watch out for |
|---|---|---|---|---|
| Project to this PC | Free | Wi-Fi (Miracast) | Two Windows laptops, quick setup | Lag; some Wi-Fi cards can’t receive |
| spacedesk | Free for private use | Wi-Fi, Ethernet or USB | Desktops on Ethernet, Miracast errors | Main PC must run Windows 10 or 11 (or a Mac driver) |
| USB capture card | Paid hardware | HDMI into USB | Consoles, cameras, lowest effort on the main PC | Capture app must stay open |
| Remote desktop apps | Often free | Internet or network | Controlling the other PC | Shows the other PC; doesn’t extend your desktop |
HP’s guide also lists remote desktop tools like Chrome Remote Desktop and TeamViewer. Use those to control the other machine from afar, not as an extra monitor.
What if both laptops are Macs?
Apple’s built-in route is AirPlay. On the Mac that will act as the screen, open System Settings > General > AirDrop & Continuity, turn on AirPlay Receiver, and choose who can connect, as described in Apple’s AirPlay guide. Both Macs need to be on the same Wi-Fi network. Then look for the receiving Mac under Screen Mirroring in Control Center on the main Mac. Mixed Windows-and-Mac setups are easier with spacedesk, which has a driver for macOS on the sending side.
How to use a second monitor with a laptop
Going the other way, using a normal monitor as a second laptop screen, is much simpler: plug the monitor into the laptop’s HDMI, DisplayPort or USB-C video port and Windows extends the desktop. If nothing appears, Microsoft’s multiple monitors guide has the fixes.
- Connect the cable firmly at both ends and turn the monitor on.
- If Windows doesn’t pick it up, open Settings > System > Display > Multiple displays and select Detect.
- Press Windows + P and pick Extend for two separate screens, Duplicate for the same picture on both, or Second screen only to use just the monitor.
- Click Identify in Display settings and drag the screens into the order they sit on your desk.
- Turn on Remember window locations based on monitor connection under Multiple displays so your windows jump back to the monitor when you plug in again.
Frequently asked questions
Can I use a laptop as a monitor for a PS5 or Xbox?
Only with a USB capture card. Consoles output HDMI, and a laptop’s HDMI port can’t take that signal in, so the card converts it into something the laptop can display.
Can a USB-C cable turn a laptop into a monitor?
Not on its own on most laptops. spacedesk lists USB as one of its connection types, but the receiving laptop still needs the viewer app running; a cable by itself doesn’t make a laptop screen accept video.
Does using a laptop as a second screen work on Windows 10?
Yes. Project to this PC exists on Windows 10 through the Connect app, and spacedesk supports Windows 10 and 11. The newer Wireless Display app needs Windows 11 version 22H2 or later.
Can I use a laptop as a 2nd monitor without Wi-Fi?
Yes. spacedesk connects over an Ethernet network or USB, and a capture card needs no network at all. Only Windows’ Project to this PC depends on Wi-Fi on both machines.
Why is my second laptop screen laggy?
Wireless projection compresses the picture and sends it over Wi-Fi, so some delay is normal. A wired spacedesk connection over Ethernet or USB, or a capture card, usually feels more responsive.
Sources
- Microsoft Support: Screen mirroring and projecting to your PC
- Microsoft Support: How to use multiple monitors in Windows
- spacedesk: official site
- HP Tech Takes: How do I use a laptop as a monitor?
- Apple Support: Stream video and audio with AirPlay on Mac
- Microsoft Q&A: Use Surface Pro 7 as second monitor for desktop PC
- Dell Community: HDMI as input in Latitude E6530
Featured image: Zesan / Pexels
