You can connect a notebook to your desktop computer and use its screen as an extra display

A notebook or laptop can work as a second monitor for a desktop computer, but it requires software to bridge the connection — your operating system does not do this automatically the way it does with a dedicated monitor. The notebook becomes a wireless or wired extension of your desktop, showing windows, documents, or applications you drag over from your main screen. This works best when the notebook is plugged in and stays in one place, since the connection drops if the notebook goes to sleep or moves out of range.

The setup takes about 10 to 15 minutes and costs nothing if you already own both devices. The trade-off is that your notebook runs two screens at once, which drains the battery faster and can slow down both machines if you are running heavy applications on each one.

Key Takeaways

  • You need third-party software like Duet Display, Luna Display, or Spacedesk to connect a notebook screen to a desktop — Windows and macOS do not have built-in remote display features.
  • Wired connections (USB or HDMI) are more stable than wireless, but wireless works if your notebook and desktop are on the same network.
  • The notebook should stay plugged into power while acting as a monitor, because running two screens drains the battery in two to four hours.
  • Latency (the delay between your mouse movement and what appears on screen) is noticeable on wireless connections and can make the notebook screen frustrating for detailed work like photo editing or coding.

Wired connection: USB or HDMI cable

A wired connection is the fastest and most stable option. You connect the notebook to the desktop using a USB cable (if the software supports it) or an HDMI cable run through a capture card. Duet Display and Luna Display both support USB connections on Windows and Mac. The cable carries both video and power, so the notebook charges while it works as a monitor.

The setup is straightforward: plug in the cable, install the software on both machines, and launch the app on each one. The connection is when ready and there is no lag. The downside is that you are tethered — the notebook cannot move more than the cable length away, and you have a physical cable running across your desk.

Wireless connection: network-based software

Wireless setup lets the notebook sit anywhere within Wi-Fi range and still display your desktop. Spacedesk (Windows and Mac) and Duet Display (Mac and iPad) both work over your home network. You install the software on both machines, connect them to the same Wi-Fi network, and the notebook screen appears as an available display in your desktop's settings.

Wireless is convenient for repositioning the notebook or using it in another room temporarily. The trade-off is latency — there is usually a 100 to 300 millisecond delay between moving your mouse and seeing the result on the notebook screen. This is tolerable for reading documents or watching video, but makes it difficult to use the notebook screen for precise tasks like drawing, photo editing, or coding. The connection also drops if Wi-Fi is weak or if the notebook goes to sleep.

Software options and what they cost

Spacedesk is free and works on Windows desktops with Windows or Mac notebooks. It runs over your network and has the lowest barrier to entry — read, install, and connect. The free version has no time limit and no feature restrictions. Spacedesk is the best choice if you want to spend nothing and do not need wired connection.

Duet Display costs $20 one-time on Mac and $15 one-time on Windows, or $10 per month for both. It supports USB wired connection and wireless over network. Duet has lower latency than Spacedesk on wireless and is faster overall, but the cost makes it worth considering only if you plan to use the notebook screen regularly.

Luna Display is a small hardware dongle ($50 to $80) that plugs into your desktop's USB port. It works with Mac notebooks and desktops and handles the video encoding on its own hardware, which reduces the load on your desktop. Luna is the fastest wireless option but requires buying the dongle and works only on Mac.

Setting up Spacedesk on Windows and Mac

read Spacedesk on your Windows desktop from spacedesk.ph. Install it and launch the process. You will see a list of available displays — this is where your notebook will appear once it connects.

On your Mac notebook, read the Spacedesk client from the same site and install it. Launch the app and you will see a list of available Spacedesk servers — your Windows desktop will appear here. Click on it to connect. Once connected, your Mac screen will show your Windows desktop, and you can drag windows between the two screens.

If the notebook does not see the desktop, check that both machines are on the same Wi-Fi network and that Windows Firewall is not blocking Spacedesk. You may need to allow Spacedesk through the firewall manually in Windows Security settings.

Setting up Duet Display on Mac and Windows

Purchase Duet Display from the App Store (Mac) or Microsoft Store (Windows), or from duetdisplay.com. Install on both your desktop and notebook. Launch Duet on the desktop first, then on the notebook. If you are using a USB cable, plug it in now — Duet will detect it and use the wired connection automatically.

For wireless, make sure both machines are on the same network. Duet will search for available desktops and display them in a list on the notebook. Tap the desktop you want to connect to, and the notebook screen will become an extension of your desktop within a few seconds.

What to expect: performance and limitations

On a wired connection, the notebook screen behaves almost like a real monitor — there is minimal lag and the connection is stable. You can use it for any task without frustration. Battery drain is not an issue because the USB cable powers the notebook.

On a wireless connection, expect a noticeable delay when moving the mouse or typing. This delay makes the notebook screen unsuitable for real-time work like video editing, gaming, or detailed design work. It works well for email, web browsing, document reading, and video playback. The notebook will lose battery in two to four hours even if plugged in, because the software uses significant CPU power to decode the video stream.

If your notebook has a lower-end processor (older Intel Core i3, AMD Ryzen 3, or equivalent), wireless performance will be slower and the notebook may get hot. Newer machines handle it better.

When a notebook screen does not make sense as a monitor

If you need a permanent second display, a used monitor costs $50 to $150 and has no software overhead, no latency, and no battery drain. A notebook screen is best for temporary setups — when you are traveling, when you need flexibility to move the notebook, or when you already have the notebook and want to test whether a second screen helps your workflow before buying a real monitor.

If your notebook is your only computer and you are trying to use it as both your main machine and a second display at the same time, the performance will suffer noticeably. The notebook will slow down because it is running two screens and your applications at once.

Frequently Asked Questions

Can I use an iPad as a monitor instead of a notebook?

Yes. Duet Display and Luna Display both work with iPad. The setup is identical — install the app on your desktop and iPad, connect them, and the iPad screen becomes a second display. iPad often has lower latency than a notebook on wireless because the software is optimized for it.

What if my notebook and desktop are different operating systems?

Spacedesk works between Windows desktops and Mac notebooks. Duet Display works between Mac and Windows in both directions. Luna Display works only on Mac. Check the software's system requirements before you buy or read.

Will using a notebook as a monitor slow down my desktop?

Slightly. The desktop has to encode the video stream and send it over the network or USB, which uses some CPU power. On a modern desktop, this is usually not noticeable. On an older machine or if you are running heavy applications, you may see a small slowdown.

Can I use the notebook for something else while it is acting as a monitor?

Not easily. The notebook screen is showing your desktop, so you cannot use the notebook's own applications at the same time. You can switch back to the notebook's own desktop, but then the second monitor display stops. Some software allows picture-in-picture, but this is not standard.

What happens if the connection drops?

On wireless, the notebook screen goes black and the connection closes. You can reconnect by launching the app again. On wired, the connection is stable unless the cable is unplugged. If the notebook goes to sleep, you will need to wake it and reconnect.