You can use a laptop as a monitor, but it requires software and works best for specific setups

A laptop can display what your desktop or another computer is doing, but it is not the same as plugging in a traditional monitor. Your laptop becomes a secondary display through software that streams the image from your main computer to your laptop's screen. This works over Wi-Fi or USB, depending on the method you choose. The laptop stays powered on and running the software the whole time, so you cannot use it for other tasks while it is acting as a monitor.

The main reason people do this is to add screen space without buying a new monitor, or to use a laptop screen temporarily when a monitor is not available. It is slower than a direct monitor connection and introduces a slight delay in what you see, which matters if you are gaming or doing video editing but is fine for email, spreadsheets, or web browsing.

Key Takeaways

  • Laptop-as-monitor software streams your desktop image to the laptop screen over Wi-Fi or USB, and the laptop cannot be used for anything else while this is happening.
  • Windows and Mac have built-in wireless display features, but they work only between computers running the same operating system.
  • Third-party software like Duet Display and Luna Display works across Windows, Mac, and iPad, but most charge a one-time or monthly fee.
  • USB connection is faster and more stable than Wi-Fi, but requires a compatible cable and limits how far apart your computers can be.
  • Expect a slight delay (lag) between what happens on your main computer and what appears on the laptop screen, especially over Wi-Fi.

Built-in options: Windows and Mac wireless display

Windows 10 and 11 have a feature called Wireless Display that lets you send your screen to another Windows computer or compatible device. On your main computer, go to Settings > System > Display > Multiple Displays, then scroll down and select "Connect to a wireless display." Your laptop will appear in the list if it is on the same Wi-Fi network and has Wireless Display turned on (Settings > System > Display > Multiple Displays > Wireless Display).

Mac computers have AirPlay, which works between Macs and also to Apple TV. Click the Control Center icon in the top right, select Screen Mirroring, and choose your laptop from the list. Both computers must be on the same Wi-Fi network and signed into the same Apple ID for this to work smoothly.

The advantage of these built-in methods is that they are free and do not require installing anything. The disadvantage is that they only work between computers running the same operating system — you cannot use AirPlay to send a Windows desktop to a Mac, or vice versa.

Third-party software that works across Windows, Mac, and iPad

Duet Display is the most widely used option for turning a laptop or iPad into a second monitor. It works between Windows and Mac, and also supports iPad as a display. You install the Duet app on both your main computer and your laptop, connect them over Wi-Fi or USB, and your laptop screen becomes a secondary display. Duet charges a one-time purchase fee (around $20) or offers a monthly subscription.

Luna Display is a hardware adapter that plugs into your Mac or Windows computer's USB port and lets you use an iPad or Mac as a second display. It is faster than pure software solutions because the adapter handles the video encoding. Luna Display costs around $50 for the adapter and works over Wi-Fi or USB-C.

Spacedesk is a free option that works between Windows computers and also supports Android tablets and phones as displays. Install the server software on your main Windows computer and the client app on your laptop, then connect over Wi-Fi. Spacedesk is slower than paid options but costs nothing.

All of these require both devices to be on the same network (or connected via USB cable), and all introduce some lag — usually 50 to 200 milliseconds depending on your Wi-Fi speed and the software you choose. For everyday work this is not noticeable, but it becomes obvious if you are moving the mouse quickly or watching video.

USB connection versus Wi-Fi: speed and stability trade-offs

Connecting your laptop to your main computer with a USB cable is faster and more stable than Wi-Fi, but it limits your setup. A USB connection reduces lag to 20 to 50 milliseconds and does not depend on your Wi-Fi signal strength. The cable also means your laptop has to sit close to your main computer — usually within 10 feet unless you use an extension cable.

Wi-Fi is more flexible because your laptop can be anywhere in range of your router, but the image quality and responsiveness depend on your network speed. If you have a 5 GHz Wi-Fi network (faster than 2.4 GHz), the lag is usually acceptable. If your Wi-Fi is slow or crowded, you may see stuttering or a noticeable delay when you move windows or type.

Most software supports both options and lets you switch between them. If you are setting up a permanent second display, USB is worth the inconvenience. If you want flexibility to move your laptop around, Wi-Fi is the trade-off you make for convenience.

What you need before you start

Check that both your main computer and your laptop meet the software's system requirements. Most third-party options need Windows 10 or later, or macOS 10.12 or later. Your Wi-Fi network does not need to be fast, but both devices must be able to connect to it — if your laptop is on a guest network and your main computer is on the primary network, they will not see each other.

If you are using USB, make sure you have a compatible cable. Duet Display and Luna Display specify which cables work with their software. A standard USB-C or USB-A cable may not work even if it physically fits, because the software needs the right data protocol.

Close any programs on your laptop that use a lot of processing power before you start. Turning a laptop into a display uses CPU and RAM to decode the incoming video stream, and if your laptop is already running heavy software, the display will lag or stutter. Closing your email client, browser tabs, and other background apps helps.

Setting up your first secondary display

The exact steps depend on which software you choose, but the general process is the same. First, install the software on both your main computer and your laptop. Second, make sure both devices are on the same Wi-Fi network (or connect them with a USB cable). Third, open the software on your main computer and look for an option to "add display" or "connect device." Your laptop should appear in a list — select it. Fourth, open the software on your laptop and confirm the connection.

Once connected, your laptop screen will show your main computer's desktop. You can drag windows between your main monitor and your laptop screen just like you would with a physical second monitor. Your main computer's taskbar or dock will show both displays as active.

If the connection drops, check that both devices are still on the same network and that the software is still running on both sides. Wi-Fi connections drop more often than USB, especially if your laptop moves far from the router or if someone else on your network is using a lot of bandwidth.

When a laptop screen does not work as a monitor

Some laptops have hardware limitations that make them poor choices for this. Older laptops with slow processors or limited RAM will lag noticeably, especially over Wi-Fi. Gaming laptops with high refresh rate screens (144 Hz or higher) will not display that smoothness when used as a secondary display — the software usually caps the refresh rate at 60 Hz.

If your laptop screen is very small (under 13 inches), the extra display space may not be worth the hassle of keeping the laptop powered on and connected. A cheap external monitor is often a better choice for permanent setups.

Laptops with integrated graphics (Intel UHD, AMD Radeon) handle this better than older models, but they still use more battery power than normal. If you are using your laptop as a display, plug it in — running on battery while also decoding video will drain it quickly.

Frequently Asked Questions

Can I use my laptop as a monitor while also using it to work?

No. When your laptop is acting as a secondary display, it is running the client software full-time and cannot be used for other tasks. You can switch back to using your laptop normally by closing the software, but then it stops being a monitor. If you need to use both devices at the same time, you need a separate physical monitor.

Will using my laptop as a monitor drain its battery?

Yes, significantly. The software uses CPU power to decode the incoming video, and the screen stays on the whole time. Always plug your laptop in when you are using it as a display. Running on battery will drain it in two to four hours depending on your laptop's battery capacity and the software you are using.

Why is there a delay when I move my mouse?

The delay (lag) happens because the video has to be compressed, sent over Wi-Fi or USB, and then decompressed on your laptop screen. This takes time — usually 50 to 200 milliseconds. USB is faster than Wi-Fi, and paid software is usually faster than free options. For typing and browsing, you will not notice it. For gaming or video editing, it becomes annoying.

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

Yes, if you use software that supports iPad. Duet Display and Luna Display both work with iPad and often perform better than using a laptop because iPads are designed for this use case. The setup is the same — install the app on both devices and connect over Wi-Fi or USB.

What if my laptop and main computer are different operating systems?

Built-in options like Windows Wireless Display and AirPlay will not work. You need third-party software like Duet Display or Spacedesk that supports cross-platform connections. Check the software's system requirements before you buy or read to make sure it supports your specific combination of operating systems.