Measure the screen’s visible height and width, not the bezel, based on whether it has a raised bezel or flat front glass.
For the full breakdown, see our best Computer Screen Protector For Eyes guide.
Getting the right fit for a screen protector comes down to one decision: what kind of edge your display has. A raised bezel means you measure only the viewable area inside the frame. A flat front glass display means you measure edge-to-edge across the entire glass surface. Getting this wrong is the most common reason a protector arrives too large or too small.
Why Screen Type Changes Your Measurement
A raised bezel sits above the screen surface, creating a visible frame around the viewable area. The protector needs to fit inside that frame, so you measure only what you see — the height and width of the display area itself, not the bezel.
Flat front glass displays have no raised frame. The glass runs edge-to-edge across the device face, so the protector must cover the entire glass surface. Measure from the outer edge of the glass on one side to the outer edge on the other, for both height and width.
Some monitor filters sold at retail take a different approach. They list a diagonal size measured corner-to-corner on the viewable display area, without the frame. This matches how monitors are marketed, even though the protector itself still needs height and width to fit properly.
Grab a tape measure and follow this order. You will need the viewable height (h) and width (w) in inches or millimeters.
- Identify the screen type: Run a finger along the edge. If you feel a raised lip around the display, you have a bezel. If the surface is smooth and continuous, you have flat front glass.
- For a raised bezel: Measure the visible display area only, keeping the tape inside the bezel on all four sides.
- For flat front glass: Measure to the outermost edges of the glass itself, including any rounded corners.
- Record both numbers: Write down the height and width. Do not rely on just the diagonal.
Once you have those two numbers, match them against the manufacturer’s size chart or custom order form. Many protectors are keyed to width × height in millimeters, not just the diagonal inches advertised on the box.
The most frequent error is measuring the outer frame instead of the viewable screen. On a laptop with a thick bezel, that mistake adds half an inch or more on each side, and the protector will not seat correctly.
Another common miss is treating a flat glass display like a bezel display. People measure only the lit area of an all-glass phone or monitor, leaving the protector too small to cover the full glass face. The opposite happens too — measuring a bezel display edge-to-edge makes the protector overlap the frame.
Relying on the headline monitor size alone also causes problems. A 24-inch diagonal can mean different heights and widths depending on the aspect ratio. A 16:9, 16:10, and 5:4 display all share a common diagonal but need different protector dimensions. Check the actual height and width before ordering.
Monitor filter listings show how this plays out. One 24-inch protector measures 24 inches diagonal, with a 20.9-inch width and an 11.8-inch height, measured on the viewable area without the frame. Some brands list millimeter dimensions instead — a 13.3-inch protector comes in at 294 × 166 mm, and a 15.6-inch version at 345 × 194 mm.
Common sizes cover most devices: 11.6, 12.1, 12.5, 13.3, 14, 15.6, 17, 19, 21, 21.5, 22, 23, 23.6, 23.8, 24, 26, and 27 inches. These correspond to standard monitor and laptop displays in 16:9, 16:10, and 5:4 formats. If your measured height and width match one of those sizes, a standard protector will fit. If they land between sizes, check whether the brand offers a custom option.