dead pixel test · refresh rate test · monitor test
Dead Pixel Test
Check your screen for dead and stuck pixels with full-screen colours, and measure your monitor refresh rate in the browser. Free, nothing to install.
Find dead and stuck pixels
Wipe the screen first, so dust does not pass for a pixel. The test fills the whole screen with one colour at a time: a dot that stays dark on white is a dead pixel, a dot that keeps one colour on the others is a stuck one.
Or open a single colour
If your browser cannot switch to full screen, the colours fill the window instead: hide the toolbars or zoom out to cover the edges.
Refresh rate test
Measures how often this tab gets a new frame. On most systems that equals the monitor refresh rate.
Lower than you expected? Check the rate in your display settings, the cable and port, battery saver mode, and, with several monitors, which screen this window is on.
Common questions
What is the difference between a dead and a stuck pixel?
A dead pixel gets no power and stays dark on every colour, which is easiest to see on white. A stuck pixel has one or more subpixels lit all the time, so it shows as a red, green, blue or white dot, which is easiest to see on black.
Can a stuck pixel be fixed?
Sometimes: a stuck subpixel can come back on its own or after the panel has been on for a while. A dead pixel usually stays. Do not press hard on the screen. If the monitor is new, check the warranty: many brands replace it only above a set number of faulty pixels.
How accurate is the refresh rate test?
The browser cannot read the monitor setting directly, so the test times frames for two seconds and rounds to the nearest standard rate (60, 75, 120, 144, 165, 240 Hz and so on). A background tab, battery saver or an app loading the system can make it read lower.