Text Sharpness Test — Free Online Test
Our Text Sharpness Test displays black text on white and white on black in multiple font sizes so you can judge subpixel rendering, anti-aliasing quality, and any softness caused by non-native resolution or aggressive scaling.
How to use the Text Sharpness Test
- Read the sample paragraphs at different sizes.
- Look for coloured fringing around letters (subpixel-rendering artifacts).
- Compare with your monitor at native resolution.
How to interpret your results
Sharp, evenly weighted glyphs indicate correct subpixel rendering. Coloured fringes around letters suggest the wrong subpixel order (RGB vs BGR) — adjust ClearType on Windows.
Common issues and what they mean
Blurry text at 4K with scaling
Some apps do not scale correctly. Right-click the app > Properties > Compatibility > Change high DPI settings.
When to run this test
- After connecting an external monitor.
- When text looks worse than expected.
Why text sharpness is a system problem, not just a panel problem
Legible text is produced by four things working together: the physical pixel density of the panel, the resolution the operating system is driving, the scaling factor applied on top of it, and the font rasteriser doing the drawing. A defect in any one of them looks identical to the eye — mushy, low-contrast letters — which is why people often blame a monitor that is working perfectly.
Start with density. A 24-inch 1080p monitor gives roughly 92 pixels per inch; a 27-inch 1440p panel gives about 109; a 15-inch laptop at 4K gives close to 294. Below roughly 110 DPI, the rasteriser must fake resolution it does not have, and glyph stems land between pixel boundaries. Above roughly 200 DPI, anti-aliasing becomes almost invisible and text looks printed.
Then check scaling. Running a 4K panel at 1440p, or setting a fractional scale like 125% on Windows, forces a resampling pass over the finished image. Every glyph is stretched by a non-integer factor and the crisp edges the rasteriser produced are averaged away. Integer scaling — 100%, 200% — avoids this entirely.
Fixing soft text on Windows, macOS and Linux
On Windows, run cttune.exe to step through the ClearType wizard; it calibrates gamma and subpixel weighting against your actual panel and takes about a minute. If a specific application looks soft while the rest of the desktop is fine, open its Properties, then Compatibility, then Change high DPI settings, and set scaling to be performed by the application rather than the system.
On macOS, prefer resolutions labelled "Looks like" a HiDPI value on 4K and 5K displays, since those render at 2x and downsample cleanly. On 1440p external monitors connected to a Mac, text often looks worse than on Windows because macOS dropped subpixel anti-aliasing in Mojave; increasing font weight in the browser or app settings usually helps more than any display setting.
On Linux, check that fontconfig has hinting and RGBA subpixel order set to match your panel. A monitor rotated to portrait needs the subpixel order changed from RGB to VRGB, otherwise every letter picks up a coloured edge.
Frequently asked questions
What is ClearType?
Microsoft's subpixel anti-aliasing technology. Run cttune.exe to calibrate.
Why does text look worse on my external monitor than on my laptop?
Laptop panels are usually higher density. At around 96 DPI each glyph has far fewer pixels to work with, so anti-aliasing has more visible work to do.
Does subpixel rendering work on OLED?
Not reliably. Many OLED panels use non-standard subpixel layouts, so RGB-assuming renderers produce colour fringing that grayscale anti-aliasing avoids.