How to Hook Up a Second Monitor to Your Computer

Connect the cable, plug in power, and Windows or Mac will recognize it automatically

A second monitor works the same way as your first one: you run a cable from your computer's video output to the monitor's video input, plug the monitor into power, and turn it on. Windows and macOS detect the new display within seconds and let you arrange them on your screen. You do not need to install drivers or restart your computer. The whole process takes under five minutes if you have the right cable.

The hard part is usually figuring out which cable you need, because your computer might have multiple video outputs and your monitor might accept several types of input. Once you know what you have, the physical connection is straightforward.

Key Takeaways

Most modern laptops and desktops have at least one video output beyond the main display — check your computer's ports before buying a cable.
HDMI and DisplayPort are the most common cables for second monitors; USB-C can carry video on newer laptops and monitors.
Your monitor needs a matching input port — if your computer outputs HDMI but your monitor only has DisplayPort, you need an adapter.
After plugging in the cable and power, open your display settings to arrange the monitors and choose whether to extend your desktop or mirror the screen.
A second monitor does not require extra graphics power on most computers, but older machines with integrated graphics may slow down noticeably.

Find the video output ports on your computer

Look at the back of your desktop or the sides of your laptop for video ports. The most common ones are HDMI (a flat rectangular port), DisplayPort (a smaller rectangular port with a notch), USB-C (a small oval port), and on older computers, VGA (a trapezoid with three rows of holes) or DVI (a rectangular port with two rows of holes).

Laptops often have only one video output, so you are limited to that one cable type. Desktops usually have multiple options — your graphics card or motherboard might have HDMI, DisplayPort, and USB-C all available at the same time. If your computer has a dedicated graphics card (Nvidia, AMD), the video ports are on the card itself, not on the motherboard. Plugging into the motherboard ports will not work.

If you cannot find any video output ports, your computer might only support video over USB-C or Thunderbolt. Some older laptops have no second video output at all — in that case, you would need a USB docking station or USB-to-HDMI adapter to add one.

Check what input ports your monitor has

Look at the back of your monitor for input ports. Most monitors have HDMI, DisplayPort, or both. Older monitors might have VGA or DVI. The monitor's manual or the label on the back will list all available inputs.

If your monitor has multiple input ports, you can use any one of them — the monitor has a button or menu to switch between inputs if you ever need to. For a second monitor, you just need one port that matches what your computer outputs, or an adapter to bridge the gap.

Buy or find the right cable

Match your computer's output to your monitor's input. If your computer has HDMI and your monitor has HDMI, buy an HDMI cable. If your computer has DisplayPort and your monitor has DisplayPort, buy a DisplayPort cable. If they do not match, you have two options: buy an adapter (a small device that converts one port type to another) or buy a cable with different ends (for example, USB-C on one end and HDMI on the other).

HDMI cables are the cheapest and most widely available. DisplayPort cables are slightly more expensive but support higher resolutions and refresh rates. USB-C video cables work on newer laptops and monitors but are less common. Adapters cost $10 to $30 depending on the type. A quality HDMI or DisplayPort cable costs $10 to $20.

Do not buy a cable longer than you need — signal quality degrades over very long distances, and you will have excess cable to manage. Most people need 6 to 10 feet. If you need more than 15 feet, use an active cable (one with a small chip inside) rather than a passive one.

Connect the cable and power

Turn off your computer and monitor before plugging anything in — this is not strictly necessary on modern equipment, but it eliminates any risk of a power surge damaging the ports. Plug one end of the cable into your computer's video output and the other end into your monitor's video input. Plug the monitor into a power outlet. Turn on the monitor, then turn on your computer.

If you are using a laptop, you can leave it running while you plug in the cable — most laptops detect the new monitor within a second or two. Wait 10 to 15 seconds after the monitor powers on before turning on your computer, so the monitor is ready to receive a signal.

Arrange your monitors in Windows or macOS

On Windows, right-click on your desktop and select "Display settings." You will see both monitors represented as numbered rectangles. Drag them around to match their physical position — if your second monitor is to the right of your main monitor, drag the rectangle to the right. This tells Windows how to move your cursor between screens.

Below the monitor arrangement, you can choose what each monitor displays. "Extend" spreads your desktop across both monitors so you have more screen space. "Duplicate" shows the same thing on both monitors. "Second screen only" turns off your main monitor and uses only the second one. Most people choose "Extend."

On macOS, go to System Settings, then Displays. Click "Arrangement" to see both monitors and drag them to match their physical layout. macOS automatically extends your desktop by default — you do not need to change anything unless you want to mirror the displays or use one as an extended display for a specific app.

Adjust resolution and refresh rate if needed

Windows and macOS automatically set your second monitor to its native resolution (the sharpest picture it can display). You usually do not need to change this. If the text looks too small or too large, you can adjust the scaling in Display Settings on Windows or System Settings on macOS.

If your second monitor supports a higher refresh rate (60 Hz, 120 Hz, or 144 Hz) and you want to use it for gaming or video work, you can change this in Display Settings on Windows. Go to Advanced Display Settings and look for "Refresh Rate." On macOS, refresh rate options appear in the Displays settings if your monitor supports them.

Troubleshooting if the monitor does not appear

If your second monitor does not show up after you plug it in, try these steps in order: First, make sure the monitor is powered on and the cable is fully inserted on both ends. Second, try a different video input on the monitor if it has multiple ports — use the monitor's menu button to switch inputs. Third, restart your computer.

If the monitor still does not appear, the cable might be faulty or incompatible. Try a different cable if you have one. If you are using an adapter, try removing it and using a cable with the correct ends instead. On Windows, you can also press Windows key + P to open the display projection menu and select "Extend" — this sometimes forces Windows to detect a monitor it missed.

If you have a laptop with a dedicated graphics card, make sure you are plugging into the graphics card's ports, not the motherboard's. On some laptops, you may need to switch to the dedicated GPU in your graphics settings before the second monitor will work.

Frequently Asked Questions

Can I use two different types of monitors at the same time?

Yes. You can connect one monitor via HDMI and another via DisplayPort, or mix any combination of input types. Windows and macOS handle different monitors without any problem. The only limitation is that each monitor must have a matching input port or an adapter to connect to your computer.

Will a second monitor slow down my computer?

On most modern computers, no. A second monitor uses very little processing power. Older computers with integrated graphics (built into the CPU rather than a separate card) may see a small slowdown, especially if you are running demanding programs like video editing or 3D games. If you notice lag, try lowering the resolution or refresh rate of the second monitor.

Do I need to buy a special cable for a second monitor?

No, a standard HDMI or DisplayPort cable works fine. You do not need an expensive "gaming" or "premium" cable — a basic cable rated for your monitor's resolution is all you need. The only exception is if you need a very long cable (over 15 feet), in which case an active cable with a built-in chip prevents signal loss.

Can I use a USB hub to connect a second monitor?

Only if your monitor supports USB video input or if you use a USB-to-HDMI adapter. A regular USB hub cannot carry video signals. Some newer monitors have USB-C ports that accept video, and some laptops can output video over USB-C, which makes a USB-C cable the simplest option.

What if my monitor has no video input ports that match my computer?

Buy an adapter that converts your computer's output to the monitor's input. For example, if your computer outputs HDMI but your monitor only has DisplayPort, a HDMI-to-DisplayPort adapter lets you connect them. Adapters are inexpensive and widely available online or at electronics stores.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.