Why use more than one screen
A second screen gives you more room to keep things in view at once. Common uses include a document on one side and a reference on the other, a video call beside your notes, or a laptop’s small screen paired with a larger display at a desk. It is not for everyone. If you mostly work in one window at a time, a single well-chosen screen can be simpler and neater.
Check what your computer can drive
Before buying, find out how many displays the computer supports and which ports it has. Laptops often manage one or two external screens, and the limit depends on the model and its graphics hardware. Desktops with a separate graphics card commonly have several outputs. Check the maker’s documentation for the number and type of displays supported, because it varies.
Then match the cables to the ports on both ends. Our explanation of display cables covers the common connectors. If a laptop has few ports, a docking station can provide extra video outputs through a single connection, though how many screens it can run depends on the laptop and the dock.
Ideally, choose monitors of similar size, resolution and height, since mismatches make the arrangement awkward. They do not need to be the same brand or model, but similar ones are easier to live with.
Physical placement
Arrange screens so you can use them without twisting your neck.
- Main screen directly in front. Put the one you use most centered at an arm’s length, with the top at or just below eye level.
- Second screen beside it. Angle it slightly toward you, with the edges close together. If both screens are used equally, place the seam between them in front of you and angle both inward.
- Matching heights. Align the tops, or the centers, so your eyes do not move up and down when you look across.
- Matching distances. Keep them at a similar distance to avoid refocusing.
Check comfort with advice on monitor position and eye strain and computer ergonomics. Extra cables behind the desk are easier to manage with cable management, and monitor arms can free up desk space. If you use a laptop beside an external screen, laptop stands can raise the laptop’s screen to a better height.
Mirroring versus extending
Once connected, the computer needs to know how to use the extra screen. The system offers a few modes, usually in the display settings or through a quick projection menu.
- Extend. The screens act as one large desktop. You can drag windows from one to the other. This is the usual choice for productivity.
- Duplicate or mirror. Both screens show exactly the same thing. This suits presentations, teaching or showing a picture on a television, but it limits you to a resolution both screens can handle, so one of them may look blurry.
- Second screen only. The main display turns off and only the external one is used. This is handy with a closed laptop at a desk.
- First screen only. The extra screen is ignored.
If a screen shows nothing after connecting, the mode may be set to a view that does not include it.
Arranging the screens in software
The settings page shows boxes that stand for each screen. These boxes tell the computer where each physical monitor sits, so that moving the mouse off one edge brings it onto the next.
- Open the display settings.
- Use the identify option to display a number on each screen, so you know which box is which.
- Drag the boxes so they match the real layout. If the second monitor sits to the left, put its box to the left.
- Align the edges the way they are on your desk. If one screen is taller or sits higher, adjust the boxes so the mouse crosses at the matching height.
- Choose which one is the main screen, which usually holds the taskbar or menu bar and where new windows tend to open.
- Apply and test by moving the mouse across.
If your pointer seems to get stuck or jump when it crosses between screens, the boxes are almost always misaligned. Nudge them and test again.
Mismatched sizes and sharpness
Two monitors with different resolutions or sizes often show windows at different sizes. Scaling is the tool for this. Setting a different scaling percentage on each screen can make text look similar in both. The article on screen resolution explains scaling and native resolution. Each screen should be set to its own native resolution, so check the recommended option for each one rather than assuming they match.
If the refresh rate differs between screens, set each one separately. Our guide to refresh rate explains how to find the setting.
Fixing common problems
- The second screen is not detected. Check the power and the input source on the monitor. Reseat the cable, try another port or cable and restart. Then look for a detect option in the display settings. If the screen stays blank, see display problems for broader fixes.
- The wrong screen is the main one. Set the main screen in the display settings so the taskbar and new windows appear where you want them.
- Windows open off-screen. This often happens when a monitor is unplugged. Switching the display mode or reconnecting the screen usually brings them back, and many systems have a keyboard shortcut for moving a window to another screen.
- Flicker on one screen. Test the cable, port and refresh rate, as described in the article on dead pixels and screen flicker.
Start with two screens before adding a third. Each extra monitor adds cables, desk space and graphics demands, and it is easier to expand a working setup than to repair a complicated one.