How To Use Your Laptop as a Second Monitor

Knowing how to use laptop as second monitor can instantly double your screen real estate without buying extra hardware. Whether you need more room for spreadsheets, coding, or video editing, a spare laptop sitting nearby is often all you need. This guide walks through every method — wired, wireless, Windows, and Mac — so you can find the setup that works for your devices.

Before diving in, make sure your primary machine is up to the task. If you're shopping for a capable host computer, browse our laptops guide for vetted picks across every budget. Understanding your laptop's processor also matters — older CPUs can struggle to push two displays simultaneously at higher resolutions.

Why Use Your Laptop as a Second Monitor?

A multi-monitor setup is one of the most well-documented productivity boosts in office computing. Research consistently shows that extra screen space reduces the time spent switching between windows and cuts errors on data-heavy tasks. Instead of buying a dedicated external display, an idle or secondary laptop can serve the same purpose.

Common use cases include:

• Keeping reference documents open while writing on the main screen
• Monitoring dashboards or chat windows without minimising your main app
• Using a second screen during video calls to see notes and slides at once
• Extending a workspace when travelling without carrying a portable monitor

What You Need Before Getting Started

Hardware Requirements

Most laptops from the last seven years support at least one wireless display protocol. For wired setups, you need a compatible cable or adapter. Check whether your laptops have HDMI-in ports — most don't, since laptop HDMI ports are almost always output-only. This is why software solutions dominate this workflow.

Software Requirements

The exact software depends on your operating system combination. Windows users benefit from built-in Miracast support, while Mac users can lean on Sidecar (for iPad) or third-party apps. A stable Wi-Fi connection on the same network is essential for wireless methods; a 5 GHz band dramatically reduces lag compared to 2.4 GHz.

How to Use Your Laptop as a Second Monitor on Windows

Windows 10 and Windows 11 include a built-in feature called Wireless Display that lets you use one Windows laptop as a second monitor for another — no cables, no third-party software required.

Using Miracast (Wireless)

Follow these steps on the receiving laptop (the one that will act as the extra screen):

1. Open the Start Menu and search for Connect, then open the Connect app.
2. The laptop is now discoverable as a wireless display.

On the source laptop (your main machine):

1. Press Windows + K to open the Cast panel.
2. Select the receiving laptop from the list of available devices.
3. Choose Extend in the projection options to create a true second display.

Miracast works entirely over Wi-Fi Direct — no internet connection needed. Latency is typically 30–80 ms, which is fine for productivity but not ideal for gaming or video playback.

Using Spacedesk (Free App)

Spacedesk is a free application that turns any Windows laptop, Android tablet, or iOS device into an additional display. Install the Spacedesk Driver on the primary machine and the Spacedesk Viewer app on the secondary device. Both machines must be on the same Wi-Fi network. The app supports up to four additional screens and includes colour depth and compression controls to tune performance on slower networks.

How to Use Your Laptop as a Second Monitor on Mac

Using Sidecar with an iPad

If your secondary screen is an iPad rather than a second laptop, Apple's Sidecar feature is the cleanest option. Sidecar requires a Mac running macOS Catalina or later and a compatible iPad. Connect via USB-C for zero-lag response or wirelessly over the same Apple ID. Go to System Settings → Displays → Add Display and select the iPad. Sidecar supports Apple Pencil input on the iPad side, which is useful for illustration or annotation work.

Using Luna Display or Duet Display

When your secondary device is a second MacBook or a Windows laptop, hardware dongles like Luna Display or the software-only Duet Display are reliable choices. Luna Display requires a small USB-C or HDMI dongle on the primary Mac; it sends a low-latency signal to the secondary device running the Luna app. Duet Display works without extra hardware and now supports Apple Silicon natively. Both options cost money but deliver noticeably lower latency than free alternatives.

A good display panel also makes the experience more comfortable. See our breakdown of IPS vs OLED vs TN laptop displays to understand how panel type affects colour accuracy and viewing angles when using a second screen.

Comparing Methods: Which Works Best?

No single method suits every situation. The table below summarises the key trade-offs to help you decide.

Tips for the Best Dual-Screen Experience

Optimise Your Network

Wireless methods depend entirely on your local network. Place both laptops close to the router or on a 5 GHz Wi-Fi band. If you experience stuttering, switch to a USB connection where the method supports it, or reduce the streaming resolution inside the app's settings.

Match Display Scaling

Mismatched screen resolutions or scaling settings cause text and icons to appear inconsistent across displays. On Windows, go to Settings → System → Display and adjust the scale percentage on each screen independently. On Mac, hold Option while clicking Scaled in Display preferences to see all available resolutions.

Manage Power and Performance

Running a second display increases CPU and GPU load on both machines. On battery, this drains power faster. Plug both laptops in for extended sessions. It's also worth keeping your data protected during long work sessions — our guide on how to back up your laptop data covers quick routines that take minutes to set up.

Adjust Colour Profiles

Different laptop panels render colour differently. If colour consistency matters for your work, calibrate both screens using the built-in colour calibration tools in Windows or macOS, or use a hardware colorimeter for precise results.

Frequently Asked Questions