Handy tools
Monitor Test
Dead pixels, refresh rate (Hz) and ghosting — test your screen in the browser, no install.
Check your monitor in seconds: cycle nine full-screen solid colors to hunt for dead or stuck pixels, estimate your refresh rate, and watch a moving block for ghosting and motion blur. Nothing to install, it runs right in your browser.
Tip: dim the lights and use full screen at 100% zoom. The Hz figure is estimated from how often the browser draws frames, so it can come out lower than your panel's spec: power-saving modes, variable refresh rate (VRR), browsers or phones that cap animation at 60 Hz, and background tabs all pull it down. On iPhone the test fills the window instead of going full screen.
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A free monitor test that runs in your browser. Cycle nine full-screen solid colors (red, green, blue, white, black, cyan, magenta, yellow and gray) to spot dead or stuck pixels, get a refresh rate estimate in Hz from the browser's frame timing, and follow a moving block with your eyes to judge ghosting and motion blur. Handy before buying a used monitor or when unboxing a new one.
Frequently Asked Questions
Q. How do I check my monitor for dead pixels?
A. Open the dead pixel test and step through nine full-screen solid colors with a click, a tap or the arrow keys. A dot that stays black on bright colors is a dead pixel; one that stays lit on black is a stuck pixel.
Q. How accurate is the refresh rate (Hz) reading?
A. It's an estimate. The tool takes the median interval between the browser's animation frames and rounds it to the nearest common rate, such as 60, 144 or 240 Hz. Power-saving modes, variable refresh rate (VRR), browsers or phones that cap animation at 60 Hz, and background tabs can make it read lower than your panel's spec.
Q. How does the ghosting test work?
A. A square slides across the screen while you follow it with your eyes. A trail or smeared edge behind it points to ghosting or motion blur. You can change the speed and switch between a black and a gray background.
Q. Do I need to install anything?
A. No. Everything runs in the browser on a laptop, desktop or external monitor. On iPhone, where web pages can't go full screen, the test fills the browser window instead.