Dead Pixel Test

Just unboxed a new monitor, laptop or phone — or noticed a suspicious dot that will not go away? A dead pixel test settles the question in about a minute. The tool above fills your whole screen with one pure colour at a time, so any pixel that is dead, stuck or misbehaving stands out instead of hiding in your wallpaper. It is free, runs entirely in your browser, and works on any screen that can open a web page. While you are checking things over, the Speed Test UK homepage can give the rest of your setup a health check too.

Dead, Stuck and Hot Pixels: What Is the Difference?

Every pixel on an LCD or OLED screen is made of three subpixels — red, green and blue — mixed in different amounts to make every colour. Faults happen at the level of a whole pixel or a single subpixel, and the type of fault decides both how it looks and whether it can be fixed.

The distinction matters because it decides your next move. A stuck pixel is worth ten minutes with the fixer further down this page. A dead pixel is a warranty conversation, not a software one.

Before You Test: Two Minutes of Preparation

Most “dead pixels” reported to support desks are not pixels at all. Give the test a fair chance:

• Clean the screen. Wipe it gently with a dry microfibre cloth. A speck of dust or a dried splash looks exactly like a black dot on a white screen, and it is by far the most common false alarm.
• Turn the brightness up. Defects are far easier to see at full or near-full brightness. On a laptop, plug the charger in so the screen does not dim itself mid-test.
• Dim the room. Reflections hide faint stuck pixels, especially bright dots on the black screen. Evening light or closed curtains make a real difference.
• Turn off night modes. Night Light, True Tone and blue-light filters tint the “white” and “blue” screens and can confuse your judgement of colours.
• Set zoom to 100% and, on a TV, open this page in the TV’s own browser or cast the tab so the whole panel is used.

How to Run the Dead Pixel Test

• Step 1: Press Start Full-Screen Test above (or tap a colour square to begin on that colour). The screen fills with black first.
• Step 2: Look slowly across the whole panel — corners and edges included. On a large monitor, move your head rather than straining your eyes; a single pixel is tiny at arm’s length.
• Step 3: Click, tap or press the spacebar to move to the next colour: white, red, green, blue, then grey. Use the left arrow key to go back if you want a second look.
• Step 4: On each colour, note any dot that does not match its surroundings — and note whether it appears on every colour or only some. That detail tells you which type of fault you have (see the table above).
• Step 5: Press Esc to finish. If you found a bright dot that is stuck on one colour, scroll down to the fixer. If you found a permanently black dot, skip to the warranty section.

What Each Colour Reveals

The Stuck Pixel Fixer: How It Works and What to Expect

The fixer on this page shows a small square that flashes rapidly through bright colours. The idea is simple: a stuck subpixel is a liquid crystal cell frozen in one position, and hammering it with rapid on-off colour changes can sometimes work it loose — the same principle as jiggling a stuck switch. Drag the square over the faulty spot and leave it running for ten to twenty minutes; stubborn cases are sometimes left for longer, with the screen kept awake.

Set your expectations honestly. Fixers work on a worthwhile minority of stuck pixels — enough to be worth trying on a free tool, nowhere near a guarantee. They do nothing at all for dead pixels, which receive no power to respond with, and nothing for dust or damage. If a stuck pixel survives two or three proper sessions, it is almost certainly permanent.

Safety first. The fixer flashes brightly many times a second. Do not use it, and do not watch the flashing area, if you or anyone nearby has photosensitive epilepsy or a sensitivity to flashing images — that is why the tool asks you to confirm the warning before it will start, and why it stops itself after twenty minutes. It is also sensible not to leave a static bright image of any kind on an OLED screen longer than the task needs.

Other Revival Methods — and One to Avoid

You will find two other folk remedies online. The first is simply leaving the screen on with moving video for several hours; it is harmless, occasionally effective for the mildest stuck pixels, and costs nothing but electricity. The second is the “pressure method” — pressing or tapping the spot through a cloth, sometimes while switching the screen on. Treat that one with real caution: on modern thin panels it is at least as likely to crack the display or create new pressure marks as it is to free a pixel, and it gives a manufacturer an easy reason to refuse a warranty claim. If the screen is under warranty, use software methods only and keep the panel pristine.

Testing Phones, TVs and Second-Hand Screens

The same test works everywhere, with small adjustments. On a phone or tablet, rotate the device and check in both orientations, and wipe the screen first — phones live in pockets and collect more dust than any other device. On a TV, sit at your normal viewing distance first: a defect you cannot see from the sofa is worth knowing about, but it is rarely worth a returns battle, whereas one you can see during dark film scenes definitely is. On a second-hand screen you are thinking of buying, this test is the single most valuable sixty seconds of the inspection — run it before money changes hands, along with a refresh rate test to confirm the panel runs at the speed it was sold as.

Found a Faulty Pixel? Your Warranty and UK Consumer Rights

Here the picture has two layers: the manufacturer’s pixel policy, and your legal rights — and in the UK the second layer is often stronger than people realise.

Manufacturer pixel policies. Most brands follow the ISO 9241-307 standard, which sorts panels into classes with permitted numbers of faulty pixels. Many consumer monitors are sold to a class that tolerates a small number of defective subpixels, so a single dim subpixel fault may be “within specification” even though it annoys you. Policies differ sharply for bright-dot faults, which are treated more strictly, and some brands offer zero-bright-pixel cover on particular ranges. Check the exact wording for your model before assuming a claim will fail — or succeed.

Your UK rights. Under the Consumer Rights Act 2015, goods must be of satisfactory quality, and if a fault appears within the first six months it is generally presumed to have been there at delivery unless the retailer proves otherwise. If you bought online, the Consumer Contracts Regulations also give you a 14-day window to change your mind and return the item for any reason — which is why testing a new screen in its first fortnight, as this page helps you do, is such a powerful habit. Your contract is with the retailer, not the manufacturer, so that is who to approach first. Citizens Advice explains the process step by step, and GOV.UK’s consumer protection pages summarise the rules in plain language.

Making a claim stick. Photograph the fault against a plain colour from this test (a phone photo of the screen is fine), record which colours show it, and note the date you first saw it. If you need technical help with a specific brand’s process, the manufacturer’s own support — for example Samsung UK support — will state the pixel policy that applies to your model.

Frequently Asked Questions

How do I tell a dead pixel from dust?

Wipe the exact spot gently with a microfibre cloth and look again. Dust moves or disappears; a dead pixel does not. Angling your head also helps — surface dust sits slightly above the image and shifts with your viewpoint, while a pixel fault is in the image and stays locked to the same position on every colour.

Can a dead pixel spread or get worse?

A single dead pixel does not spread like a crack — it is one failed element, not an infection. A screen that starts collecting several new faults, though, may have a failing panel or driver, and that pattern is worth reporting under warranty promptly rather than watching and waiting.

How long should I run the stuck pixel fixer?

Start with ten to twenty minutes — the tool stops itself at twenty. If the pixel flickers or improves, a second session is reasonable. If two or three full sessions change nothing, the subpixel is very likely permanently stuck and further flashing is unlikely to help.

Is one dead pixel enough for a refund or replacement?

It depends on how and when you bought the screen. A manufacturer’s warranty may treat one fault as within tolerance, but if you bought online in the UK you can usually return the item within 14 days for any reason, and the Consumer Rights Act gives you a short-term right to reject goods that are not of satisfactory quality within 30 days. Outside those windows it becomes a discussion about the brand’s pixel policy.

Does the test work on OLED screens?

Yes — dead and stuck subpixels show up on solid colours on OLED exactly as on LCD, and the test is also a quick way to spot OLED uniformity issues and image retention on the grey screen. Keep sessions short and avoid leaving any single bright colour displayed for a long time afterwards.

Why can I see the dot in films but not on my desktop?

Because contrast gives it away. A bright stuck pixel is invisible against a bright desktop but obvious in a dark film scene on the black screen; a dead pixel does the opposite. That is exactly why the test uses both extremes and the primary colours — between them, no type of fault has anywhere to hide.

One Minute Now Saves the Argument Later

A new screen’s first fortnight is when your rights are strongest and faults are easiest to act on, so make this test part of every unboxing: scroll up, run through the six colours, and either relax with a clean result or act quickly with photographs and dates in hand. And if you are setting up a whole new machine rather than just a screen, finish the job at Speed Test UK by checking the connection it will live on.