Many users are faced with the need to expand their workspace when one screen is no longer enough to comfortably work with tables, code or editing software. Buying a new monitor is an additional expense and a problem with desk space, so the logical question arises: can you use a second laptop you already have on hand as an additional display?
The answer is clear: yes, it is technically possible, but the implementation depends on the operating system and the desired result. A direct connection with HDMI cables “from laptop to laptop” will not work, since the connectors on modern devices are usually output, not input. However, there are software solutions that transmit a video signal through a local network, emulating the operation of a second screen.
Why can't you just connect laptops with an HDMI cable?
The most common mistake when trying to expand your screen is trying to connect two devices with a standard HDMI cable. In the vast majority of cases, the connector on the laptop body is intended only for signal output, that is, for transmitting a picture to an external monitor or projector.
In order for the second laptop to receive the signal via cable, its video input must be implemented in hardware as Video In. Such connectors are extremely rare, mainly in professional gaming models or specific business series, but even there they are rather an exception to the rule. Connecting a regular cable between two laptops will do nothing, since both devices will try to “scream” at each other, but neither will be able to “hear” the incoming signal.
The exception is some older models or specialized capture cards, which can be inserted into an expansion slot, but this requires additional cost and complex setup. For the mass user, the only working option is to use software that transmits images via the Internet or local network.
Connection methods via software
There are several proven ways to turn an old laptop into a monitor. The easiest and free option is built into the Windows 10 and 11 operating system called Project to This PC. This method does not require the installation of third-party software if both devices are running the latest versions of the OS.
An alternative is specialized utilities such as Spacedesk, Deskreen or Mouse without Borders combined with remote access features. These programs often provide a more stable picture and lower latency than standard Windows tools, especially if the connection is via an Ethernet cable rather than Wi-Fi.
For Apple ecosystem users, Sidecar may be a solution, but it only works between Mac devices, which limits its use in mixed environments. In any case, the key success factor is the quality of the network connection and processor performance on both devices, since both laptops will spend resources encoding and decoding the video stream.
Setting up the built-in Windows Project function
Let's start with the most accessible method that is already in your system. On the laptop that is to become the second screen, you need to go to Settings → System → Project to This PC. If the options you want are hidden, you will need to install the Wireless Display component through Additional Features.
After enabling the function on the second device, open Settings → System → Display and select "Connect to a wireless display." The name of your second laptop will appear in the list of available devices. Click on it and the system will ask for permission to connect on the second device.
After connecting, you can configure the operating mode: “Expand” to add a work area, or “Duplicate” to show the same picture. It is important to note that input lag in this mode can be noticeable, so this method is not suitable for dynamic games, but for working with text or static interfaces it is quite acceptable.
- Wireless via Wi-Fi
- Wired via LAN
- Built-in Windows feature
- Third party programs
Using Spacedesk for Flexible Setup
If the built-in Windows tools are unstable or you want to connect a laptop with a different operating system, the program will be an excellent solution Spacedesk. This cross-platform application allows you to use a second screen on almost any device with a browser or client installed.
The setup process begins with installing the server driver on the main computer and the client application on the second laptop. Once both applications are launched, they automatically discover each other on the local network. The program interface allows you to fine-tune picture quality, frame rate and resolution, which is especially important when working via Wi-Fi.
A special feature of Spacedesk is support for touchscreens: if the second laptop has a touchscreen, it will work as a touchmonitor for the main system. This opens up interesting possibilities for designers and engineers who need an additional interactive control panel.
☑️ Preparing to connect Spacedesk
Network requirements for Spacedesk
For comfortable work with high resolution (1080p), it is recommended to use an Ethernet cable for both devices. 5 GHz Wi-Fi is also suitable, but micro-freezes are possible when transmitting video.
⚠️ Attention: Use Spacedesk only on a secure local network. Transmission of a video stream over open public networks may lead to data interception.
Comparison of connection methods and performance
The choice of connection method directly affects the comfort of work. Built-in Windows tools are convenient in their simplicity, but often suffer from high latency (lag) and compression artifacts. Third-party programs such as Spacedesk usually do a better job, but require additional software to be installed and can be CPU-intensive.
The speed of operation also critically depends on the type of network connection. A connection via 5 GHz Wi-Fi is acceptable for office tasks, but for video or graphics work it is better to use a wired connection through a router. The Ethernet cable guarantees minimal latency and no data packet loss.
Below is a table comparing the main parameters of different connection methods:
| Method | Delay (lag) | Picture quality | Difficulty setting up | Audio support |
|---|---|---|---|---|
| Windows Projection | Average | good | Low | Yes |
| Spacedesk (Wi-Fi) | High | Average | Average | Yes |
| Spacedesk (LAN) | Low | Excellent | Average | Yes |
| Remote Desktop (RDP) | Very low | High | High | No (in extended screen mode) |
Limitations and possible problems
Despite the convenience, you should understand that a second laptop will not become a full-fledged monitor. It consumes power, takes up desk space, and requires dedicated space for the keyboard and touchpad if you don't plan to use them. In addition, the battery of the second device will drain much faster if the display is constantly on.
Another limitation is resolution. If the main laptop has a 4K screen and the second one has Full HD, the system may display incorrect scaling of interface elements. You will have to manually configure Scale and layout in the display settings so that the text is readable on both devices.
In some cases, antivirus software or firewall may block the connection, mistaking the software for a threat. If devices cannot see each other, check your firewall settings and allow access for selected programs on your private network.
Before you begin, close unnecessary applications on both laptops to free up RAM and CPU time for processing the video stream.
When does using a second laptop make sense?
Using a second laptop as a monitor is ideal for scenarios where you need to have reference information, chats, email, or server monitoring at your fingertips. It's also a great solution for sharing content during meetings when you need to quickly flip the screen to a nearby device.
This method is not suitable for gaming or professional video work due to the inevitable signal delay. In these cases, it is better to invest in a quality external monitor with low response latency and high refresh rate.
However, for students, freelancers, and those working remotely, it's a free way to double your workspace without breaking the bank. The main thing is to choose the right software and ensure a stable network connection.
Using a second laptop as a monitor is a compromise solution that is great for office tasks, but will not replace a full-fledged display for games and video editing due to signal delays.
Frequently asked questions and answers
Can I use a second laptop for gaming?
Technically it is possible, but it will be uncomfortable to play. The signal delay when transmitted over the network, even under ideal conditions, ranges from 50 to 200 milliseconds, which is critical for dynamic shooters or racing. This is acceptable for strategy or turn-based games.
Will the second laptop lose some performance?
Yes, the processor and video card will be used to decode the video stream. If the laptop is weak, it can lead to overheating and poor performance on the main device. It is recommended to use powerful models as second screens.
Does this work on Windows 7 or 8?
The built-in projection feature is only available in Windows 10 and 11. For older versions, you will have to use third-party programs like Spacedesk, but their support may be limited.
Do I need an HDMI cable for setup?
No, setup takes place entirely via a local network (Wi-Fi or Ethernet). An HDMI cable is not used because laptop connectors usually do not support video input.
Can I connect a laptop to a Mac as a monitor?
The built-in Sidecar feature only works between Mac and iPad. To connect a Windows laptop to a Mac or vice versa, you will have to use third-party utilities such as Duet Display or Luna Display.