Yes, you can connect a Dell monitor to another monitor, but the method depends on which Dell model you have and what you want the second display to do

Most Dell monitors have one or more video input ports on the back — typically HDMI, DisplayPort, or VGA. If your Dell has a spare input port, you can plug a second monitor into it using the matching cable. However, this does not make the two monitors work as one screen. Instead, your computer will treat them as separate displays, and you control which one shows what through your operating system's display settings.

The confusion usually comes from thinking a monitor is a hub or splitter. It is not. A monitor receives a signal from your computer and displays it. Plugging a second monitor into the first monitor's spare port does nothing unless that second monitor is also connected to your computer. Both monitors must have their own cable running back to your computer's graphics card or USB port.

If you want to add a second display to your setup, the real question is whether your computer has a second video output port. Most laptops have one HDMI or USB-C port. Most desktop computers have at least two. That is what limits you, not the Dell monitor itself.

Key Takeaways

  • A Dell monitor's spare input port cannot pass a signal to a second monitor — both monitors must connect directly to your computer.
  • Check your computer's video output ports (HDMI, DisplayPort, USB-C, or VGA) to see how many monitors it can support at once.
  • If your computer has only one video output, you can use a USB docking station or external graphics adapter to add a second display.
  • Once both monitors are connected to your computer, Windows and macOS let you arrange them side by side, extend your desktop across both, or mirror the same image on both.

How to check what ports your Dell monitor has

Look at the back of your Dell monitor. You will see a cluster of ports. The most common ones are HDMI (a flat rectangular port), DisplayPort (a smaller rectangular port with a notch), and VGA (a blue port with three rows of small holes). Some newer Dell monitors also have USB-C ports.

Write down which ports you see. This tells you what cables you can use to connect the monitor to your computer, but it does not tell you whether you can daisy-chain monitors. Daisy-chaining — connecting one monitor to another — only works if your monitor supports DisplayPort daisy-chaining, which is rare and requires both monitors to have DisplayPort inputs and outputs. Most Dell monitors do not support this.

If your Dell monitor has a USB port or USB-C port, that is for charging devices or connecting a keyboard, not for video. Do not try to plug a video cable into a USB port.

What your computer's video ports actually determine

Your computer, not your monitor, decides how many displays you can run at once. Open your computer's display settings and look for how many monitors are currently detected. On Windows, right-click the desktop and select "Display settings." On a Mac, go to System Settings and click "Displays."

If your computer shows only one monitor connected, adding a second monitor requires a second video output port on your computer. Laptops often have only one HDMI port or one USB-C port. Desktop computers usually have at least two ports on the graphics card. If you have used up all your ports, you will need an external solution.

Some computers have video outputs you may not have noticed. Check the back of your desktop tower or the sides of your laptop carefully. USB-C ports on newer computers can output video. Thunderbolt ports (on Macs and some Windows laptops) can also output video. If you find a second port, you can use it with the right cable or adapter.

Adding a second monitor when your computer has only one video port

If your computer has only one video output and you want to add a second monitor, you have two practical options: a USB docking station or a USB-to-HDMI adapter.

A USB docking station is a box that plugs into one USB port on your computer and provides multiple video outputs on the back. You can then plug both monitors into the docking station. Docking stations range from about $40 to $200 depending on how many ports they have and how fast they are. Popular brands include Lenovo, Dell, and Anker. This is the most reliable option for laptops.

A USB-to-HDMI adapter is a small cable adapter that converts a USB port into an HDMI port. These cost $15 to $50 and work on both Windows and Mac, though some are more stable than others. The downside is that they use USB bandwidth, which can slow down your computer if you are also transferring large files or using other USB devices. They work best for light use like email and web browsing.

Before you buy either option, check your computer's USB ports. You need a USB 3.0 port or newer (usually marked with a blue interior or a "3.0" label). USB 2.0 ports are too slow for video and will not work reliably.

Setting up two monitors once both are connected to your computer

Once both your Dell monitor and your second monitor are plugged into your computer, Windows and macOS will detect them automatically. You then decide how they work together through display settings.

On Windows, right-click the desktop, select "Display settings," and scroll down to the "Multiple displays" section. You can choose to extend your desktop (each monitor shows a different part of your workspace), duplicate your desktop (both monitors show the same thing), or use only one monitor. Most people choose extend, which gives you more screen space.

On a Mac, go to System Settings, click "Displays," and then click "Arrangement." You can drag the monitor icons to match how they are physically positioned on your desk. This helps your cursor move naturally from one screen to the other.

You can also adjust the resolution and refresh rate of each monitor separately. If one monitor is older or smaller, you may want to lower its resolution so text is not too small. These settings are in the same display settings menu.

Common reasons a second monitor does not work

If you plugged in a second monitor and your computer does not detect it, check these things in order. First, make sure the second monitor is powered on — look for a light on the front of the monitor. Second, make sure the cable is fully inserted into both the monitor and your computer. Third, try a different cable if you have one, because video cables fail more often than you would expect.

If the cable and power are fine, restart your computer. Windows and macOS sometimes need a restart to detect a newly connected monitor. If it still does not appear, check your computer's display settings to see if the monitor is listed but turned off. On Windows, you can right-click the desktop and select "Display settings," then scroll down and click "Detect" to force your computer to search for monitors.

If you are using a USB docking station or adapter, the issue might be a driver. Windows sometimes needs to read a driver for USB video adapters. Go to Device Manager (search for it in the Windows search bar), look for any devices with a yellow warning triangle, right-click them, and select "Update driver." Choose "Search automatically for updated driver software."

Frequently Asked Questions

Can I plug a second monitor into the back of my Dell monitor?

Only if both monitors are also connected to your computer. A monitor's spare input port receives a signal from your computer, not from another monitor. If you plug a second monitor into your Dell's spare port without connecting it to your computer, the second monitor will show nothing. Both monitors must have their own cable running to your computer.

What if my Dell monitor has DisplayPort — can I daisy-chain?

Most Dell monitors with DisplayPort cannot daisy-chain, even though the port technically supports it. Daisy-chaining requires both the monitor and your computer to support DisplayPort 1.2 or newer with daisy-chain enabled. Check your monitor's manual or Dell's website to confirm. If it does support daisy-chaining, you can connect one monitor to your computer and the second monitor to the first, using only one video port on your computer.

Do I need a special cable to connect two monitors?

No. Use whatever cable matches the ports on your monitor and computer — HDMI to HDMI, DisplayPort to DisplayPort, or USB-C to USB-C. If your monitor and computer have different port types, use an adapter. A $10 HDMI-to-DisplayPort adapter, for example, lets you connect an HDMI monitor to a DisplayPort output on your computer.

Will adding a second monitor slow down my computer?

A second monitor connected directly to your computer's graphics card will have almost no impact on speed. If you use a USB adapter or docking station, there may be a small slowdown because the video signal shares USB bandwidth with other devices. This is usually not noticeable for everyday tasks, but it can matter if you are transferring large files at the same time.

Can I use a monitor as a hub to charge my phone while displaying video?

Only if your monitor has a USB hub built in, which some Dell monitors do. Check the back of your monitor for USB ports. If it has them, they are usually powered and can charge devices. However, these USB ports still cannot pass video signals to another monitor — they only handle data and power.