Monitor sharpness test: spotting scaling blur and soft text

How this is calculated

A display has a fixed grid of pixels. A one pixel black line next to a one pixel white line only looks crisp when each canvas pixel lands on exactly one panel pixel. Three things commonly break that. A non-native resolution makes the monitor stretch the image, which blurs everything. Browser zoom other than 100% resizes the page. Operating system scaling at a fractional setting, like 125% or 150%, maps one CSS pixel to a non-whole number of device pixels. The test asks the browser for the canvas size in exact device pixels where it can, which avoids most of the blur from scaling and zoom. A note at the top of the pattern says whether that worked. If it says the lines are only about one device pixel wide, your browser doesn't report exact device pixels, and some softness is expected. On very large or very high resolution screens, the canvas is capped to keep memory use reasonable, and the note says so. Look at the horizontal lines, the vertical lines and the checkerboard separately. Moire or shimmer in the checkerboard is normal on some panels. Color fringes on text often come from subpixel text smoothing rather than the panel. Turn the monitor's sharpness setting to neutral, since extra sharpening adds halos.

Verdict

Set the monitor to its native resolution in your operating system, browser zoom to 100%, and the monitor's sharpness to its neutral value. If the line pairs then look crisp, the panel is fine and any soft text comes from scaling choices. Pick a scale that suits your screen size and distance, and remember that a higher pixel density hides scaling blur better.