Screen / Dead Pixel Test
Cycle solid colors full-screen to spot dead or stuck pixels.
Go full screen, then click the color area (or press Space/→) to cycle through solid colors — look closely for any pixel that stays a different color than the rest, or an area that flickers. Press Esc to exit full screen.
About this tool
Cycle a monitor or phone screen through solid black, white, red, green, blue, and gray to spot dead pixels (permanently dark), stuck pixels (permanently lit one color), or backlight bleed/uniformity issues — go full screen for the clearest test, since a spot outside the test area won't be visible.
Why several colors, not just one. A single defective pixel can fail in different ways depending on which sub-pixel (red, green, or blue) is affected, and a given failure is only visible against certain backgrounds. A stuck-red pixel blends invisibly into a red or white screen but stands out sharply against black, green, or blue. Cycling through all six test colors — black, white, red, green, blue, and gray — guarantees every type of stuck or dead sub-pixel gets at least one background it can't hide against.
Dead vs. stuck vs. hot. The three terms get used loosely, but they describe different failures:
| Type | Behavior | Usually fixable? |
|---|---|---|
| Dead pixel | Stays black on every color — receiving no power at all | No — a hardware fault |
| Stuck pixel | Locked on one color (often pure red, green, or blue) regardless of the intended image | Sometimes — massaging or specific stuck-pixel software can un-stick a sub-pixel transistor |
| Hot pixel | Displays a color when it should be off (more of a camera-sensor term, but visually similar) | No, on a display panel |
Backlight bleed and uniformity show up differently — not as a single dot, but as a lighter patch or glow, usually near the edges or corners, most visible against the full-black screen in a dark room. This is a backlight/panel-uniformity issue rather than a single failed pixel, and some amount of it is normal on LCD panels; it's only worth acting on if it's clearly visible during normal (non-full-black) use.
How to run the test properly. Go full screen (the button, or your browser's own fullscreen shortcut), dim the room if you can, and look closely at the entire panel on each color — not just the center. Cycle with the Space bar or arrow keys so you don't have to look away from the screen to click. A brand-new display is worth checking within the manufacturer's return window, since even one or two stuck pixels can qualify for a replacement under some warranty policies (dead-pixel policies vary a lot by manufacturer).
What this can't do: it can't fix a defect, and it can't tell you whether a manufacturer's specific dead-pixel policy covers what you found — check the panel maker's warranty terms for the acceptable-defect threshold, which is often surprisingly lenient (some allow several stuck sub-pixels before qualifying as defective).
To check other hardware before or alongside a new display, see the webcam test and mouse tester, or the keyboard tester for a new peripheral.
Frequently asked questions
- What's the difference between a dead pixel and a stuck pixel?
- A dead pixel stays black no matter what color is displayed (it's not receiving power). A stuck pixel stays fixed on one color (often red, green, or blue) regardless of what the screen should show — both show up as a fixed dot that doesn't match the surrounding solid color during this test.
- Why test with multiple colors instead of just white?
- A stuck-red pixel is invisible against a white or red background but obvious against black, green, or blue — cycling through all the primary colors plus black and white catches stuck pixels of any color.
- Can this test fix a dead or stuck pixel?
- No — this only helps you find one. Some stuck (not dead) pixels can sometimes be resolved with gentle pressure or dedicated pixel-fixing techniques you'd look up separately; a genuinely dead pixel is a hardware issue this (or any software) can't repair.
- What's backlight bleed, and how do I spot it?
- Light leaking around the edges of an LCD panel's backlight, most visible as a glow near the corners on the full-black screen in a dark room. It's a panel/backlight uniformity issue, not a single failed pixel, and a small amount is normal on most LCDs.
- Should I return a new monitor over one stuck pixel?
- Check the manufacturer's dead-pixel policy first — many allow a small number of defective sub-pixels before qualifying as a warranty defect, and policies vary significantly between brands and even between monitor lines from the same brand.
- Does this work on phone and tablet screens too?
- Yes — it's just a full-screen colored page, so it works on any device with a browser. Use the browser's own fullscreen/immersive mode if the "Full screen" button behaves differently on mobile.