How the dead pixel test works
Click Start and the whole screen fills with one colour. Click, or press the right arrow or the space bar, to move to the next colour; the left arrow goes back and Esc ends the test. The colours come in this order: black, white, red, green, blue, grey and yellow. Above the button the page shows the screen's resolution, its scaling and its refresh rate.
What to look for
- A dead pixel stays black on every colour. It is easiest to spot on white.
- A pixel stuck on one colour always shows red, green or blue. It is easiest to spot on black.
- A pixel that always shines white shows up on black as a bright dot.
- Bright patches near the edges on black usually come from the backlight leaking at the edges of the panel, not from faulty pixels.
- Darker or lighter areas on grey show that the panel's brightness is uneven.
Tips
Clean the screen first with a soft cloth, because a speck of dust looks very much like a dead pixel. When you find a suspicious dot, switch the colours a few times: a faulty pixel is always in the same place and behaves the same way on every colour, while dust disappears when you wipe the screen. Look at each colour from your normal viewing distance and then from closer, with the screen at full brightness, because faults are easier to miss when it is dim. Test a new monitor, laptop or TV as soon as it arrives: manufacturers have their own rules on how many faulty pixels qualify for a replacement, and the shop's return period is limited. Note where the faulty pixel is, so that you can show it to the seller or the service centre.
Other things to check on a new screen
The resolution shown above the button should match the screen's native resolution from its specification; a lower setting makes the picture blurry. If a 144 Hz monitor shows 60 Hz here, set the refresh rate in your system's display settings and check that the cable and the port support it, because many HDMI ports and cables limit the refresh rate at high resolutions. Your full PC specs, including the graphics card, are on the PC specs page.
Questions
Can a dead pixel be fixed?
A pixel that is completely black usually cannot. A pixel stuck on one colour sometimes recovers after rapidly changing colours, but there is no guarantee.
How many dead pixels are acceptable?
That depends on the manufacturer's pixel policy, which differs between brands and product lines. Check the warranty terms of your monitor, laptop or TV.
Does the test work on phones and TVs?
Yes, in any browser. On some phones the browser bars stay visible because the browser does not allow a page to fill the whole screen.
Why is the refresh rate lower than my monitor's?
The page measures how often the browser draws frames. Check the refresh rate set in your system's display settings; some laptops lower it on battery.
What is the difference between a dead and a stuck pixel?
A dead pixel gives no light and stays black on every colour. A stuck pixel keeps one of its red, green or blue parts lit, so it shows a coloured dot that is best seen on black.
Should I test a laptop screen the same way?
Yes. Set the screen to full brightness, clean it, and look at every colour. On laptops, also check black for light leaking near the hinge and the edges.
Is the test safe for my screen?
Yes. It only shows solid colours, like any other picture.