Most laptops can work as a second screen for another computer, but the method depends on what you are trying to connect. Windows has a built-in wireless display feature that turns any compatible laptop into a Miracast receiver. Third-party apps like SpaceDesk and Duet Display do the same thing over Wi-Fi or USB. A capture card lets you display a gaming console on your laptop screen.
The one thing you cannot do with most laptops is plug in an HDMI cable and use the screen directly. Laptop HDMI ports are almost always output-only. This guide covers every working method in 2026, including the workarounds for that HDMI limitation.
How to Use a Laptop as a Second Monitor with Miracast
Windows 10 and Windows 11 both include a feature called Wireless Display, which uses the Miracast protocol. It lets another Windows PC project its screen to your laptop wirelessly over Wi-Fi. No extra software is needed. Both computers just need to be on the same Wi-Fi network.
This feature was previously called “Project to this PC” in Windows 10. In Windows 11, Microsoft renamed it to “Wireless Display” but the functionality is identical. You turn it on in the laptop that will act as the monitor, then connect from the main PC.
How to set up Wireless Display on the receiving laptop
- Open Settings on the laptop you want to use as a monitor.
- Go to System > Projecting to this PC (Windows 10) or System > Projection settings (Windows 11).
- If you see a message saying “Add the Wireless Display optional feature,” click the link and install it. This is a one-time download of about 10 MB. Windows will prompt you to restart afterward.
- Once installed, set “Some Windows and Android devices can project to this PC when you say it’s OK” to “Available everywhere” or “Available everywhere on secure networks.”
- Set “Ask to project to this PC” to “First time only” or “Every time” depending on your security preference.
- Leave the laptop powered on and connected to Wi-Fi.
How to connect from the main PC
- On the main PC (the one whose screen you want to extend), press Windows + K to open the Cast panel.
- Your laptop’s name should appear in the list of available displays. Click it.
- The laptop will show a permission prompt. Accept the connection.
- Once connected, go to Display Settings on the main PC. The laptop screen appears as a second display. Set it to “Extend” mode to use it as an additional workspace.
Miracast works well for office tasks, web browsing, and document editing. Expect a slight delay of 50 to 100 milliseconds, which is noticeable if you try to watch video or move windows quickly. The display resolution is typically capped at 1080p regardless of the laptop’s native panel resolution.
Can You Use a Laptop as a Monitor with an HDMI Cable
This is the most common question people ask, and the answer is almost always no. The HDMI port on a laptop is an output port. It sends video from the laptop to an external display. It does not accept video input from another device.
A few rare laptops have had HDMI input ports over the years. The Alienware 17 R4 (2017) and some older Lenovo IdeaCentre all-in-ones included a physical HDMI-in switch. These models are discontinued and hard to find in 2026. No current mainstream laptop from Dell, HP, Lenovo, Asus, Acer, or Apple ships with HDMI input capability.
| Port Type | Direction | Can Accept Video Input? |
|---|---|---|
| HDMI (standard laptop) | Output only | No |
| Mini HDMI / Micro HDMI | Output only | No |
| USB-C (DisplayPort Alt Mode) | Output only | No |
| Thunderbolt 3/4 | Output only | No |
| HDMI-In (rare models only) | Input | Yes |
There is no adapter, cable, or converter that can turn an HDMI output into an input. If you see products online claiming to do this, they do not work. The hardware limitation is in the laptop’s display controller, not the cable. The only way to get video into a standard laptop is through software or a USB capture card.
How to Use SpaceDesk to Turn a Laptop into a Second Monitor
SpaceDesk is a free application that extends your main PC’s desktop to another laptop, tablet, or phone over a local network. It works on Windows 10 and Windows 11 and supports connections over Wi-Fi, USB tethering, or a direct Ethernet cable between two machines.
SpaceDesk has two components. The driver runs on the main PC (the one whose screen you want to extend). The viewer app runs on the device you want to use as the extra display.
- On the main PC, download and install the SpaceDesk Driver from spacedesk.net. Choose the correct version for your Windows architecture (64-bit for most modern PCs). Restart the PC after installation.
- On the laptop you want to use as a monitor, download and install the SpaceDesk Viewer from the same website. There are also viewer apps for Android, iOS, and iPadOS if you want to use a tablet instead.
- Make sure both devices are on the same Wi-Fi network.
- Open the SpaceDesk Viewer on the laptop. It will automatically detect the main PC running the SpaceDesk Driver. Click the PC’s name to connect.
- The main PC’s extended desktop will appear on the laptop screen. Open Display Settings on the main PC to arrange the monitor positions and set the resolution.
SpaceDesk is free for personal use with no watermark or time limit. Performance depends heavily on your Wi-Fi quality. On a 5 GHz network, latency stays around 20 to 40 milliseconds, which is acceptable for productivity work. On a congested 2.4 GHz network, lag becomes very noticeable. For the lowest latency, connect both devices to the router with Ethernet cables or use a USB tethering connection.
How to Use Duet Display to Make a Laptop a Monitor
Duet Display started as an iPad-to-Mac mirroring tool and has expanded into a full multi-device display solution. It works on Windows, macOS, iOS, Android, and Chromebook. The paid version (Duet Air) supports wireless connections. The base version works over a USB cable only.
- Download and install Duet Display on both the main PC and the laptop you want to use as a display. Create a Duet account if prompted.
- For a wired connection, connect the two devices with a USB cable. Duet automatically detects the connection and extends the desktop to the second device.
- For a wireless connection (requires Duet Air subscription at $3.33/month billed annually), open the app on both devices and connect through the Duet account interface. Both devices must be on the same Wi-Fi network.
- Adjust resolution, frame rate, and performance quality in the Duet Display settings panel. Higher quality uses more bandwidth and CPU.
Duet Display provides noticeably better performance than Miracast, especially over a USB cable. Wired connections deliver near-zero latency and support higher refresh rates. The wireless mode through Duet Air performs similarly to SpaceDesk over Wi-Fi.
SpaceDesk vs Duet Display vs Miracast for Second Screen
| Feature | Miracast (Windows) | SpaceDesk | Duet Display |
|---|---|---|---|
| Price | Free (built-in) | Free | Free (wired) / $3.33/mo (wireless) |
| Connection type | Wi-Fi only | Wi-Fi, USB, Ethernet | USB (free) / Wi-Fi (paid) |
| Typical latency | 50-100 ms | 20-40 ms (5 GHz Wi-Fi) | 5-15 ms (USB) / 20-40 ms (Wi-Fi) |
| Max resolution | 1080p | Up to 4K | Up to 4K |
| Requires install | Optional feature only | Yes (both devices) | Yes (both devices) |
| Works cross-platform | Windows and Android only | Windows + Android/iOS viewers | Windows, macOS, iOS, Android, ChromeOS |
| Good for gaming | No | No | No (wired is borderline) |
For occasional use where you just need extra screen space for email or a document, Miracast is the easiest option because there is nothing extra to install. SpaceDesk is the best free option for regular use. Duet Display is worth the subscription if you need cross-platform support or frequently switch between wired and wireless setups.
How to Use an Old Laptop as a Monitor for a Gaming Console
Connecting a PlayStation, Xbox, or Nintendo Switch to a laptop requires a USB capture card. The console’s HDMI output plugs into the capture card, and the capture card plugs into the laptop’s USB port. Software on the laptop then displays the console’s video feed in a window.
A capture card is the only way to do this because, as covered earlier, laptop HDMI ports do not accept input. The capture card acts as an intermediary, converting the HDMI signal into a USB data stream the laptop can process.
- Buy a USB capture card that supports your console’s output resolution. For PS5 and Xbox Series X at 1080p 60fps, an Elgato HD60 X or AVerMedia Live Gamer Mini works well. Budget USB capture cards from brands like EVGA or generic dongles handle 1080p 30fps for around $15 to $25.
- Connect the console’s HDMI cable to the capture card’s HDMI input port.
- Connect the capture card to the laptop via USB (USB 3.0 or higher recommended for smooth performance).
- Open the capture card’s companion software on the laptop. Elgato uses 4K Capture Utility, AVerMedia uses RECentral. For generic cards, OBS Studio (free) works with virtually every capture card on the market.
- Power on the console. The video feed should appear in the software window on the laptop. Set the capture resolution to match the console output, and toggle fullscreen mode for the best viewing experience.
There are important trade-offs with this approach. Every capture card introduces some input lag, typically 50 to 150 milliseconds depending on the card and the software processing pipeline. Budget cards at the higher end of that range make fast-paced competitive games feel sluggish. An Elgato HD60 X with passthrough would be ideal if you had a separate TV, but if you only have the laptop screen, you are stuck with the software preview and its inherent delay.
Audio comes through the capture card as well. You can listen through the laptop’s speakers or headphone jack once the capture software is receiving audio from the console.
What Are the Limitations of Using a Laptop as a Monitor
Every method described in this guide has compromises compared to using a proper external monitor. Before committing to any of these setups, understand what you are giving up.
Latency is unavoidable. Wireless methods (Miracast, SpaceDesk over Wi-Fi, Duet Air) all add enough delay that video playback looks slightly off and mouse movements feel floaty. Wired USB solutions reduce this but do not eliminate it completely. None of these methods are suitable for competitive gaming or precision video editing.
Resolution is often limited. Miracast caps at 1080p. Software solutions can theoretically push higher resolutions, but the processing overhead on older hardware makes anything above 1080p impractical. Budget capture cards top out at 1080p 30fps, which is not ideal for modern consoles capable of 4K output.
Network dependency. Wireless solutions require a stable, uncongested Wi-Fi network. If your router is handling heavy traffic from streaming, downloads, or other devices, the extended display will stutter and drop frames. A 5 GHz band or dedicated connection helps significantly.
Battery drain. Running a laptop as a secondary display while receiving a wireless stream or processing a capture card feed puts substantial load on the battery. Keep the laptop plugged in during extended use.
Touch and pen input. When using a laptop as a wireless display via Miracast, you cannot use the laptop’s touchpad or keyboard to control the main PC. The laptop essentially becomes a passive display. SpaceDesk and Duet Display do allow touch input on the extended display, which makes them better options if the secondary laptop has a touchscreen.
Using a Laptop as a Monitor FAQs
Can I use a Mac laptop as a monitor for a Windows PC?
Not natively. Miracast is a Windows-only protocol, so a MacBook cannot act as a Miracast receiver. Duet Display is the best option for cross-platform setups because it supports both macOS and Windows. Install Duet on both machines, connect over USB or Wi-Fi (Duet Air subscription required for wireless), and the MacBook becomes an extended display for the Windows PC. Luna Display is another hardware option that works across platforms but costs around $130 for the dongle.
Does using a laptop as a monitor affect its performance?
Yes, but the impact depends on the method. Miracast and SpaceDesk use minimal resources on the receiving laptop because the main PC does most of the rendering work. Running a capture card with OBS Studio is more demanding because the laptop’s CPU and GPU handle the video decoding. On a laptop with at least an Intel Core i5 or AMD Ryzen 5 processor, the performance hit is manageable. Older or budget laptops may struggle with higher resolutions and frame rates.
Can I use a broken laptop screen as a monitor for another device?
Not without disassembly. If the laptop screen is physically intact but the laptop itself is broken, you can technically remove the LCD panel, buy a compatible LCD controller board for that specific panel model, and wire it up as a standalone monitor. Controller boards cost $20 to $40 and connect via HDMI or VGA. This requires opening the laptop, disconnecting the ribbon cable, and matching the exact panel model number to a compatible controller. It is a viable DIY project but not a quick solution.
What is the best free software to use a laptop as a second monitor?
SpaceDesk is the best free option in 2026. It has no watermark, no time limit, and supports Wi-Fi, USB, and Ethernet connections. The only requirement is that the main PC runs Windows. For the receiving device, SpaceDesk offers viewer apps for Windows, Android, and iOS. If both machines are Windows PCs and you want a zero-install solution, the built-in Miracast wireless display feature works without downloading anything extra.
Can I extend my desktop to a laptop with just a USB cable?
Yes, with the right software. Duet Display supports USB connections natively. SpaceDesk also works over USB tethering. You cannot just plug a USB cable between two computers and have it work as a display connection. The cable handles data transfer only. You need software running on both ends to convert that data stream into display output. A standard USB-A to USB-A cable will not work either. Use a USB-C cable or a USB-A to USB-B cable depending on what ports are available.
Sources
Microsoft – Project to a wireless display with Miracast – support.microsoft.com, SpaceDesk Official Documentation – spacedesk.net, Duet Display Support – duetdisplay.com, Elgato HD60 X Specifications – elgato.com, OBS Studio – Open Broadcaster Software – obsproject.com, Microsoft – Wireless Display optional feature – learn.microsoft.com
