How to identify which monitor Windows is using

Windows shows Display 1 and Display 2, but those labels do not tell you which physical monitor is which. If an app opens on the wrong screen, or you are changing resolution and scale, it helps to match the Windows labels to the monitors on your desk first.

Use Windows display settings to label each screen, then compare them with the Screens tool. It lists connected screens with their resolution and scale, and lets you run a color test on a chosen screen.

Identify each monitor

1. Open the Screens tool on the Windows computer you are checking. Note the resolution and scale shown for each connected screen.
2. Open Windows display settings with Windows + I, then go to System › Display.
3. Select Identify. Windows briefly places a number on each connected monitor. Look at the physical screens and note which one shows 1, 2, or another number.
4. Compare the screen sizes and resolutions in Windows with the details in Screens. For example, a 1920 by 1080 monitor should match the entry with that resolution, unless Windows is using a different display mode or scale.
5. If you are unsure, select a screen in Screens and run its color test. Watch which physical monitor changes. Repeat for the other screens if needed.

If a laptop is connected to an external monitor, keep the laptop lid open while you identify the screens. If the external screen is blank, check that it is powered on and set to the correct input before concluding that Windows does not recognize it.

What the result means

Windows numbers both monitors and Screens lists both

Windows and the browser can see both displays. Use the number shown on each physical screen to identify its Windows display rectangle. Then compare the resolution and scale to make sure you are changing the settings for the screen you intend.

Windows numbers a monitor, but Screens does not list it

Windows recognizes the monitor, but the browser test is not reporting it. Reload the tool and check again. If the difference remains, use Windows display settings as the source for which screens are connected. Browser access to screen details can vary by browser and system configuration.

Screens lists a display, but Windows does not show it

Check the Windows display arrangement and connection. A screen listed in the browser is not proof that Windows is actively using it as an extended desktop. In Windows 11, go to Settings › System › Display and look under Multiple displays for the available display controls.

The number is not the monitor you expected

Windows display numbers are labels, not a ranking of monitor quality or importance. Display 1 is not always the built-in screen, and Display 2 is not always the external monitor. Use Identify whenever you need to match a number to a physical screen.

The app is on a different monitor than the main display

This can be normal. Windows can use several screens at once, and the main display does not force every app window to open there. A window may reopen on the monitor where it was last used. The main display setting controls which monitor Windows treats as primary, not which display is currently showing a particular app.

How to fix a monitor that is not where you expect

1. Choose the right display mode. Press Windows + P and select Extend to use separate desktops on multiple screens, or Duplicate to show the same desktop on each. PC screen only and Second screen only turn off one of the displays.
2. Set the main display if needed. In Windows 11, open Settings › System › Display, select the numbered display you want, and turn on Make this my main display if that option appears. On macOS, the equivalent display controls are under System Settings › Displays; the Windows numbering steps do not apply there.
3. Move the display rectangles to match your desk. In Settings › System › Display, drag the display rectangles so their positions match the physical layout. This makes it easier to move the pointer across the correct edge. Select Apply if Windows asks you to confirm the layout.
4. Check the monitor input and cable. Use the monitor's input control to select the port connected to the computer. Reseat both ends of the cable, then try another compatible port or cable if you have one.
5. Ask Windows to detect the screen again. Open Settings › System › Display, expand Multiple displays, and select Detect if it is available. If Windows still cannot find a screen that works with another computer, the monitor, cable, adapter, or dock may need repair or replacement.

Display number, main display, and app location

These are three different things. The number identifies a screen in Windows settings. The main display is the screen Windows treats as primary, and the active app window is simply the window currently open on one of the screens. A monitor can be Display 2, be set as the main display, and show the app you are working in.

To find where a particular app is open, look at the visible screens or move its window between them. If you change the display arrangement or disconnect a monitor, Windows or the app may remember a different window position the next time it opens.