The Three Ways to Share a Monitor Between Two Computers

You can connect two computers to one monitor using a KVM switch, a monitor input selector, or software screen sharing. Each method works differently and suits different situations. A KVM switch lets you control both computers from one keyboard and mouse. A monitor input selector requires you to manually switch between video inputs. Software sharing lets one computer display another computer's screen over your network.

The method you choose depends on whether you want to switch between computers when ready, use both at the same time, and whether the computers are in the same room. Most people find a KVM switch the easiest option because it feels like using one computer, even though two are running.

Key Takeaways

  • A KVM switch connects to both computers and your monitor, letting you switch between them with a button press or keyboard shortcut, and share one keyboard and mouse.
  • A monitor input selector (HDMI or DisplayPort switcher) costs less than a KVM but requires you to manually switch video inputs and still needs separate keyboards and mice.
  • Software screen sharing like Chrome Remote Desktop or TeamViewer works over your network and lets you control one computer from another without extra hardware.
  • Check your monitor's input ports (HDMI, DisplayPort, VGA, USB-C) and your computers' video outputs before buying a switch or cable.
  • KVM switches with USB hubs let you share printers and other USB devices between computers, not just the keyboard and mouse.

Using a KVM Switch for Full Control of Both Computers

A KVM switch (keyboard, video, mouse) is a small box that sits between your two computers and your monitor, keyboard, and mouse. When you press a button on the switch or use a keyboard shortcut, it when ready switches which computer controls the monitor and peripherals. You type on the same keyboard and move the same mouse, but the input goes to whichever computer you have selected.

To set up a KVM switch, connect the video cable from your monitor to the switch's monitor output port. Then connect video cables from each computer to the switch's two input ports. Plug your keyboard into the keyboard port and your mouse into the mouse port on the switch. Plug both computers into power and turn them on. Most switches work when ready with no software installation needed.

KVM switches come in two-port (two computers) and four-port (four computers) versions. Prices range widely depending on the video quality they support. A basic HDMI KVM switch costs around $30 to $60. If you need 4K video support, expect to pay $80 to $150. Some switches include USB hubs so you can also share a printer or external hard drive between computers—plug the USB device into the switch instead of directly into a computer.

Using a Monitor Input Selector for Video Only

A monitor input selector (also called a video switcher or HDMI switcher) is simpler and cheaper than a KVM switch, but it only switches the video signal. You still need a separate keyboard and mouse for each computer. When you want to switch which computer appears on the monitor, you press a button on the switcher to change the video input.

To set up an input selector, connect your monitor's video cable to the switcher's output port. Connect video cables from each computer to the switcher's two input ports. Turn on both computers. When you want to see the other computer's screen, press the button on the switcher to switch inputs. You then type on that computer's keyboard and use that computer's mouse.

Input selectors cost $15 to $40 and work with HDMI, DisplayPort, or VGA cables depending on the model. They are useful if you want to keep your computers' keyboards and mice separate, or if the computers are far apart and you cannot easily reach a shared keyboard and mouse. The main drawback is that you have to physically switch the input each time, and you cannot use one keyboard and mouse for both computers.

Using Software Screen Sharing Over Your Network

If both computers are on the same network, you can use screen sharing software to control one computer from the other without buying any hardware. The controlling computer displays the other computer's screen in a window. You can type and move the mouse as if you were sitting at that computer.

Common screen sharing tools include Chrome Remote Desktop (free, built into Google Chrome), TeamViewer (free for personal use), and Microsoft Remote Desktop (free on Windows). To use Chrome Remote Desktop, install the extension on both computers, sign in with the same Google account on the computer you want to control, and then open the extension on the computer you are using. Click the computer you want to control and a window opens showing its screen.

Screen sharing works well if the computers are in different rooms or if you only need to control one computer occasionally. The downside is that you see the other computer's screen in a window rather than full-screen on your monitor, and there is a slight delay between when you type and when the text appears. For everyday work where you switch between computers frequently, a KVM switch feels faster and more natural.

Checking Your Monitor and Computer Ports Before You Buy

Before purchasing a switch, check what video ports your monitor has on the back. Most modern monitors have HDMI or DisplayPort inputs. Older monitors may have VGA (the blue three-row connector) or DVI ports. Write down which ports your monitor has.

Next, check the video output ports on each computer. Desktop computers usually have a video port on the back of the tower. Laptops have a video port on the side or back. Common outputs are HDMI, DisplayPort, USB-C (which can carry video), VGA, or Mini DisplayPort. Make sure both computers have the same type of output, or that your switch supports mixed inputs—for example, one computer with HDMI and one with DisplayPort.

If your monitor and computers use different connector types, you will need an adapter cable. For example, if your computer has DisplayPort but your monitor has HDMI, you can buy a DisplayPort-to-HDMI adapter cable for $10 to $20. Adapters work in one direction only, so check that the adapter goes from your computer's output to your monitor's input.

Common Mistakes to Avoid When Setting Up

The most common mistake is buying a switch that does not match your video ports. A KVM switch that only has HDMI inputs will not work if one of your computers has DisplayPort. Always check the switch's input and output ports against your computers and monitor before ordering.

Another mistake is plugging the monitor's cable into the wrong port on the switch. The switch has one output port (where the monitor plugs in) and two or more input ports (where the computers plug in). If you plug the monitor into an input port by mistake, nothing will display. Check the switch's label or manual to identify the output port.

A third mistake is not powering on the switch itself. Many KVM switches need to be plugged into a power outlet to work. If you plug in the computers and monitor but forget to plug in the switch, nothing will happen. Check that the switch has a power light on the front.

Finally, some people buy a switch that does not support the video resolution their monitor needs. If you have a 4K monitor but buy a basic HDMI switch rated for 1080p only, the image will be blurry or the monitor will not display anything. Check the switch's specifications to make sure it supports your monitor's resolution.

Switching Between Computers Quickly

Once your KVM switch is set up, you can switch between computers in three ways. Most switches have a physical button on the front that you press to cycle through the connected computers. Some switches have a remote control with buttons for each computer. The fastest method is usually a keyboard shortcut—many switches let you press a special key combination (like Scroll Lock twice) to switch computers when ready.

Check your switch's manual to see which switching method it supports. If you switch computers many times per day, a keyboard shortcut is faster than reaching for a button. If you rarely switch, a physical button is fine. Some switches let you set a timer so they automatically switch back to the primary computer after a set time, which is useful if you use one computer most of the time.

Frequently Asked Questions

Can I use a monitor input selector if my computers have different video ports?

Yes, but you will need adapter cables. If one computer has HDMI and the other has DisplayPort, buy a DisplayPort-to-HDMI adapter for the DisplayPort computer. Plug the adapter into the computer's DisplayPort, then plug an HDMI cable from the adapter into the switcher. Make sure the adapter is rated for the video resolution you need.

Will a KVM switch work with wireless keyboards and mice?

Most KVM switches do not work with wireless keyboards and mice because the wireless receiver plugs into a computer, not the switch. However, some newer KVM switches have wireless capability built in. Check the product description before buying. If you want wireless, look for a switch that explicitly says it supports wireless peripherals.

What happens to my other USB devices when I switch computers on a KVM switch?

If your KVM switch has a USB hub, any USB devices plugged into the hub will switch with the keyboard and mouse. If you plug a USB device directly into a computer instead of the switch, it stays connected to that computer and does not switch. To share a printer or external drive, plug it into the switch's USB hub port.

Can I use a monitor input selector with a laptop that closes when not in use?

Yes, but you need to change your laptop's power settings so it does not sleep when the lid closes. On Windows, go to Settings > System > Power & Sleep > Additional Power Settings > Choose What Closing the Lid Does, and select "Do Nothing" for both battery and plugged in. On Mac, go to System Preferences > Energy Saver and uncheck "Put Hard Disks to Sleep When Possible."

Is there a delay when using screen sharing software like Chrome Remote Desktop?

There is usually a slight delay of 50 to 200 milliseconds depending on your network speed and the software you use. This is noticeable when typing or moving the mouse, but acceptable for most tasks. If you need zero delay, a hardware KVM switch is faster because it switches the video signal directly without going through your network.