Screen Test

A screen test is a set of full-screen patterns that reveal display faults you cannot see in everyday use. This free guided test walks any monitor, phone or TV through solid color fields, uniformity grays, gradients, sharpness grids and a geometry check, so you can spot dead pixels, tints, backlight bleed and banding in a few minutes. Just hit start above and the tool coaches you through each step with plain notes on what a healthy and a faulty screen look like.

Clean the panel first, then run the screen test full-screen and scan slowly across each solid color field for any dot that does not match its surroundings. The white screen test exposes dark dead pixels, the black screen test reveals bright stuck pixels, and the red, green and blue fields expose faulty sub-pixels. Cycling through all of them is the standard way reviewers catch the most defects in one pass.

A dead pixel stays permanently black because all its sub-pixels are off, while a stuck pixel is locked on a single color such as red, green or blue. You can tell them apart by cycling through the color fields in this test: a stuck pixel changes how visible it is from one screen to the next, but a dead pixel looks like the same black dot every time. Knowing which you have matters, because the fixes are very different.

A true dead pixel usually cannot be fixed, since it is permanently off and typically needs a panel replacement or warranty claim. Stuck pixels are more hopeful and often respond to rapidly cycling colors, with tools like JScreenFix having a fair success rate. Use this screen test first to confirm whether you have a dead pixel or a fixable stuck one before you decide what to do.

Turn off the lights, open the black screen test in full screen and look along the edges and corners for any glow or bright clouds. A little even edge glow is normal on most LCD and IPS panels, but large bright patches are backlight bleed worth questioning on a new screen. For the most accurate read, keep brightness at your normal level and let the display warm up for a few minutes first.

Each catches faults the other hides. The white screen test makes dark dead pixels, dust, smudges and yellow tints jump out, while the black screen test reveals bright stuck pixels, clouding and backlight bleed. Running both back to back, as this tool does, is the quick professional way to surface most display defects in well under two minutes.

This tool focuses on image quality, but you can do a basic touch screen test by drawing one continuous line across every part of the screen in a notes or drawing app and watching for gaps where your finger stops registering. Pay extra attention to the edges and corners, which fail most often, and remove any case or screen protector first. Many phones also include a built-in touch test in their hidden diagnostics or service menu.

Open this page in your phone's browser and start the test; the patterns fill the whole display and you swipe to move between them, which makes it a quick iphone screen test on any model. On an oled screen test, expect perfectly black blacks with no backlight bleed, so use the black and gray fields to hunt for faint burn-in or image retention instead. If a ghost image fades after a few minutes of varied content it was temporary retention, not permanent burn-in.

Dead pixels are isolated points that fail no matter what is shown, while uniformity is about brightness and color staying even across the whole panel. The 50% gray field in this test is the best way to judge uniformity: look for darker corners, blotches or a faint dirty-screen effect rather than single dots. Both are worth checking, since a panel can be free of dead pixels yet still look uneven.

Test any new monitor, phone or TV within the first day or two so you can still return or exchange it if a fault shows up, ideally before a retailer's 30-day window closes. After that, a quick check every few months, or any time an image suddenly looks off, is plenty to catch new dead pixels or developing tints early. Because this screen test is free and runs in the browser, re-running it later takes only a couple of minutes.