How to check monitor geometry on a vertical display

A vertical monitor can make a page look wrong even when the screen is working properly. Text may look stretched, a circle may look oval, or windows may appear sideways or cut off. The cause could be the display orientation, resolution, an app setting, or the monitor itself.

Start by confirming which screen the computer sees and what resolution and scale it reports. TooLab's Screens tool can show those details for each connected display and open a color test on a screen. It does not draw a geometry grid, so use a familiar circle or square in an app to check shape proportions.

Check the vertical display

1. Open Screens and find the portrait display in the list. Note its reported resolution and scale. If you have multiple displays, compare the entries so you know which one you are checking.
2. Open your computer's display settings and select that same monitor. In Windows 11, go to Settings › System › Display, then choose Identify to match the number on the screen to the display in settings. On macOS, open System Settings › Displays and select the vertical monitor.
3. Check the orientation and resolution settings. Windows should use Portrait or Portrait (flipped), depending on how the monitor is physically turned. On macOS, check Rotation if that option is available. Choose the recommended or default resolution before testing proportions.
4. Open an image or document that contains a known circle and square. View it on the vertical display without stretching the image to fill a different-shaped window. Reset browser zoom with Ctrl + 0 on Windows or Command + 0 on macOS if you are using a browser.
5. Check more than one app and window size. A shape that looks correct in one app but distorted in another points toward that app's zoom, layout, or image-fitting setting rather than the monitor panel.

If you need help matching the display in Windows settings, see how to identify which monitor Windows is using.

What the result means

Circles look round and squares have equal sides

The display is showing shapes with the expected proportions. If text or buttons still seem too large or small, check the operating system's scale setting and the app's zoom. Scaling changes the size of interface elements, but should not turn a circle into an oval.

Circles look oval in every app

First confirm that the source image has not been stretched to fit its frame. Then check the monitor's selected resolution and any aspect ratio or image-size option in its on-screen menu. A wrong signal or scaling mode can stretch the picture. Many monitors have a setting such as Aspect, Wide, or 1:1, but the names vary by model.

Shapes look right, but the desktop is sideways or cut off

This is more likely an orientation or resolution setting than a physical geometry problem. Set the display to the correct portrait orientation and use the recommended resolution. If the image is cut off at the edges, inspect the monitor's overscan or image-size setting, if it has one.

Only one app looks stretched

The monitor is probably displaying its image correctly. Check the app's zoom, presentation layout, or image fit mode. For a picture, choose an option that preserves its aspect ratio, such as Fit or Keep proportions, rather than stretching it to fill the window.

The resolution or scale seems unexpected

The operating system may have selected a lower resolution, or a dock, adapter, or graphics driver may be limiting the available choices. Compare the display's reported details in Screens with the options shown in display settings. A browser can report screen details, but it cannot tell whether a cable or panel is physically damaged.

How to fix a geometry problem

1. Set the correct orientation. In Windows 11, open Settings › System › Display and select the portrait orientation. On macOS, open System Settings › Displays and set Rotation if the control is available. Choose the flipped option only if the screen is mounted upside down.
2. Use the recommended resolution. In Windows 11, select the display and choose the value marked Recommended under Display resolution. On macOS, choose the default resolution in System Settings › Displays. A non-native resolution can make fine details look softer, though it should not normally change the shape of the entire image.
3. Reset scale and app zoom. In Windows 11, check Settings › System › Display › Scale. On macOS, choose the default display setting first, then check the individual app's zoom. Scale changes the apparent size of text and controls, not the monitor's physical shape.
4. Check the monitor's own picture controls. Open its on-screen menu using the physical buttons or joystick. Look for aspect ratio, image size, or overscan controls, and restore a normal or automatic setting. The exact labels depend on the monitor.
5. Reconnect the display path. Unplug and firmly reconnect the video cable at both ends. If you use a dock or adapter, connect the monitor directly to the computer for a comparison, or try another cable and input.
6. Restart and update the graphics driver if needed. If the correct orientation or resolution is missing, restart the computer. On Windows, check for graphics driver updates from Windows Update or the computer maker. On macOS, install available system updates through System Settings › General › Software Update.

When it may be a hardware problem

Test the monitor with another computer or video input, using the monitor's recommended resolution. If circles remain visibly stretched across multiple devices and cables, and the monitor's own picture settings do not correct it, the display or its internal processing may be faulty. If the monitor's built-in menu also looks warped, that is another reason to contact the manufacturer or a repair shop. For a new display, document the issue and check the return or warranty terms before opening the case.

A browser-based screen check can confirm reported resolution and scale, but it cannot measure the physical dimensions of a panel or diagnose damaged display circuitry.