A dead pixel test fills your screen with one solid colour at a time so that any pixel which is not doing its job has nowhere to hide. It takes about two minutes, it needs nothing but a browser, and it is the only reliable way to tell a genuine panel fault from a speck of dust — which is what most reported dead pixels turn out to be. This page covers how to prepare the screen, how to run the test on a monitor, phone or television, and how to read the result.
On this page
- What is a dead pixel test? — what the test actually does, and why solid colours are the whole trick
- How do you prepare your screen for a dead pixel test? — the four steps that stop you chasing dust and software artefacts
- How do you run a dead pixel test in your browser? — the fastest route on any computer, phone or tablet
- How do you test a TV for dead pixels? — the video route for anything you cannot open a browser on
- How do you tell a dead pixel from a stuck pixel? — the black-then-white check that decides whether it is worth fixing
- What should you do after a dead pixel test? — try the fixer on a stuck pixel, document a dead one
- How do you test a phone, tablet or laptop screen? — what changes on high-density and built-in displays
- How often should you test your screen for dead pixels? — the moments when a test actually changes the outcome
What is a dead pixel test?
A dead pixel test displays a series of full-screen solid colours — black, white, red, green and blue — and asks you to look for anything that does not match. That is the entire method, and it works because a broken pixel can only hide inside a busy image. Against a uniform field it has nothing to blend into.
Each colour catches a different fault. A pixel that has lost power stays black, so it disappears on a black screen and stands out sharply on a white one. A pixel jammed on shows a colour permanently, so it is invisible against its own colour and obvious against black. Running only one colour is the most common reason people miss a fault that is genuinely there.
How do you prepare your screen for a dead pixel test?
Skipping the preparation is why most dead pixel reports are false alarms. Four things matter, and together they take less than a minute:
- Clean the panel. Dust and grease account for a large share of suspected dead pixels, and they wipe away. Use a dry microfibre cloth and no household glass cleaner — the safe method avoids the pressure that aggressive wiping applies, which can create real faults.
- Turn off colour filters. Night Light, Night Shift, True Tone, HDR and any blue-light filter all alter what the panel actually displays. A warm-tinted white is not a clean white, and it hides pale faults.
- Kill reflections. Work in a room without a lamp or window reflecting off the glass. A reflection reads convincingly as a bright dot until you move your head.
- Run at native resolution. A scaled display blurs a real single-pixel fault into something that looks like softness. Our screen resolution test confirms it in seconds.
Set brightness to something comfortable rather than maximum. A very bright panel washes out the dark end and makes a dead pixel on white harder, not easier, to spot.
How do you run a dead pixel test in your browser?
Open the test, put it full screen, and step through the colours. The test runs in the browser, so there is nothing to install and nothing to grant permissions to — which is worth saying plainly, because downloadable “pixel repair” utilities do nothing a full-screen colour in a browser does not already do.
- Open the dead pixel test and press F11, or the full-screen control, so no browser chrome remains on screen.
- Start on black and look for any dot that is lit. Take your time and scan in bands rather than staring at the middle.
- Move to white and look for any dot that is dark.
- Step through red, green and blue. A single failed sub-pixel hides on its own colour and shows clearly on the other two.
- Note where anything suspicious sits on the screen so you can find it again.
Look from your normal viewing distance first, then closer. Pressing your face to the glass reveals the pixel grid itself on a low-density panel, which is normal and not a fault.
How do you test a TV for dead pixels?
Most televisions will not give you a usable browser, so the test comes as video instead. Our full-screen test videos play the same colour sequence at the correct aspect ratio, and run from a USB stick, a casting app or the TV’s own media player.
Before you judge anything on a television, turn off motion smoothing, dynamic contrast, local dimming and any eco or power-saving mode. All of them change what actually reaches the panel: dynamic contrast in particular can crush a dark area until a dead pixel vanishes, and local dimming can invent a bright patch that looks like a fault and is not.
Pick the video that matches your screen shape. A 16:9 sequence letterboxed onto a 21:9 panel leaves black bars, and you will not have tested the strips underneath them.
How do you tell a dead pixel from a stuck pixel?
This is the part of the result that actually changes what you do next, because one of the two is often repairable and the other never is.
- Visible on white, invisible on black — a dead pixel. It has lost power and produces no light at all. No software will bring it back.
- Visible on black, invisible on white — a stuck pixel. It is still powered and jammed showing one colour, and a decent share of these can be recovered.
- Visible on black and white, in white — a hot pixel, all three sub-pixels jammed on. It behaves like a stuck pixel and responds to the same treatment.
- Moves, or disappears after a reboot — not a pixel fault at all. A crashed graphics driver or a failing cable produces artefacts that look convincing until you test them this way.
Our side-by-side comparison of dead and stuck pixels goes through the rest of the distinguishing signs, and what a dead pixel is covers the underlying failure.
What should you do after a dead pixel test?
If the test came back clean, you are done — and it is worth repeating on the day any new screen arrives, because that is when a claim is easiest. If it did not, what follows depends on which fault you found.
A stuck pixel is worth attempting. Cycling colours through it at speed can shake the jammed sub-pixel loose. It is non-invasive, carries no risk to the panel, and costs nothing but time. Leave our dead pixel fixer running over the fault for at least an hour, having first turned off automatic sleep.
A dead pixel is a warranty question. There is no software fix. Photograph it on both a black and a white background, note where it sits, confirm it survives a reboot and a cable change, then check your manufacturer’s pixel policy — most set a threshold before a panel counts as defective, and premium and professional displays are stricter. What to do about a dead pixel walks through the claim.
Either way, tell us how your test went. We publish the results by manufacturer, and they are the reason we can say anything useful about which brands ship clean panels.
How do you test a phone, tablet or laptop screen?
The method does not change, but the details do.
On a phone or tablet the pixel density is high enough that a single failed sub-pixel can hide completely at arm’s length. Turn the brightness up, hold the screen at your normal distance first, then bring it closer. Disable auto-brightness so the panel does not shift mid-test. Testing a phone screen covers the specifics, and there is a dedicated guide for testing an iPhone.
On a laptop, check the lid hinge area and the edges carefully: pressure from a closed lid is a common cause, and faults cluster where the panel is stressed. On an external monitor, test through the cable and input you actually use, then repeat on a second cable before concluding anything — testing a monitor covers what to document.
On an OLED panel, expect the opposite bias: a failing OLED sub-pixel tends to go dark rather than jam bright, so dead pixels are far more common than stuck ones and the LCD fixes do not transfer. See pixel faults on OLED before trying anything.
How often should you test your screen for dead pixels?
There is no value in testing a healthy screen on a schedule, and none at all in running a colour-cycling pattern preventively — it has no protective effect and simply adds hours of use. Test when the result can still change something:
- The day a new screen arrives. A manufacturing fault is present from the first power-up, and most return windows and pixel policies are tied to a short period after purchase. This is the one that matters.
- Before a return window closes on any device with a display.
- When buying second-hand, ideally in front of the seller.
- After an impact or a spill, where damage can keep spreading for weeks.
- When you think you have seen something. Confirming a dot is dust is worth two minutes.
If you want the broader panel health check — backlight bleed, contrast, banding and uniformity as well as pixels — our LCD screen health guide runs the full set in order.
