How to do a dead pixel test
- Clean the screen. Wipe it with a dry microfibre cloth. Dust and smudges look a lot like dead pixels, especially on white.
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Start the test. Click Start full-screen test, or pick a colour to begin with. The colour fills the whole screen.
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Step through the colours. Click, tap, or press Space or → for the next colour, and ← or right-click to go back. On a phone or tablet, swipe sideways. Each colour’s name and what to look for appear briefly at the top.
- Scan every colour closely. Work across the screen section by section, including the corners and edges. Any dot that doesn’t match the colour on screen is a faulty pixel.
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Exit. Press Esc or use the × button in the toolbar. On a touchscreen, swipe down to show the controls first. The status then shows how many of the 11 screens you checked.
Turn on Auto-cycle in the settings to change colours by themselves every 2 to 10 seconds, so you can sit back and watch the whole screen. The cursor hides after a moment so it doesn’t get in the way.
Keyboard shortcuts
- Space Next colour
- → Next colour
- ← Previous colour
- A Auto-cycle on or off
- Esc Exit the test
Dead pixel test not working? Fix it step by step
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The colour doesn’t fill the whole screen. If the test says True full screen isn’t available in this browser, it fills the browser window instead. That’s normal on iPhone, where Safari keeps its toolbars on screen, so the thin strips behind them aren’t tested. On a computer, make the browser itself full screen first — press F11 on Windows or Linux, the full-screen key on a Chromebook, or Ctrl+Cmd+F on a Mac — then start the test again.
- Keys don’t change the colour. Click the colour screen once so the browser window has keyboard focus (this also moves to the next colour), then use Space or the arrow keys. On a TV remote, use the arrow keys or the toolbar buttons.
- The controls disappeared. The toolbar and cursor hide after a moment so they don’t cover any pixels. Move the mouse, press Tab, or swipe down on a touchscreen to bring them back.
- The test closes by itself. Anything that takes the browser out of full screen ends the test too, such as Esc, F11 or switching apps on a phone. Pick the swatch you were on to carry on from there.
- White looks yellow or tinted. Turn off blue-light filters while you test. Windows 11/10: Settings › System › Display › Night light. Mac: System Settings › Displays › Night Shift, and turn off True Tone. iPhone and iPad: Settings › Display & Brightness — turn off Night Shift and True Tone. Android: turn off Night Light or Eye comfort shield in the display settings.
- Not sure if it’s a pixel or dust? Wipe the spot and look again. Dust moves or disappears; a faulty pixel stays in exactly the same place on every colour. Your phone camera’s zoom or a magnifying glass helps on high-resolution screens.
Dead, stuck or hot pixel?
Every pixel is made of three sub-pixels — red, green and blue — that mix to create each colour. What a faulty pixel looks like on the different test screens tells you what has gone wrong:
| Fault | What you see | Easiest to spot on | Can it be fixed? |
|---|---|---|---|
| Dead pixel | A black dot that never lights up | White, red, green and blue | Rarely — the pixel’s transistor or connection has usually failed |
| Stuck pixel | A dot stuck on red, green, blue or a mix such as cyan or yellow | Black, and colours it doesn’t match | Sometimes — try the Stuck Pixel Fixer |
| Hot pixel | A white dot that never turns off | Black | Occasionally — treat it like a stuck pixel |
A dot that is black on white but looks normal on black is dead. One that glows on the black screen is stuck or hot. If only one colour is affected — say, a dark dot on the green screen only — a single sub-pixel is faulty.
What the other screens check
- Cyan, magenta and yellow each light two of the three sub-pixels, which makes a single sub-pixel stuck on or off easier to see.
- Gray shows uneven brightness, colour tints, and the blotchy “dirty screen effect” some large panels have.
- Gradients fade from black to full white, red, green and blue. Visible steps (banding) or tints point to limited colour depth or image processing, not faulty pixels.
- Backlight bleed is pure black. In a dark room, light leaking from the edges or corners of an LCD shows up as bright patches; a soft glow that shifts as you move your head (IPS glow) is normal. OLED screens should stay completely black.
How to inspect the screen properly
Pixels on a modern phone or 4K monitor are tiny, so one faulty pixel is easy to miss. These habits make it much easier to find:
- Test in a dim room. Stuck and hot pixels glow clearly on the black screen, and bleed only shows in the dark.
- Look straight at the screen from about arm’s length first, then move closer to check anything suspicious.
- Set your screen to its native resolution, so each pixel on the test is one real pixel.
- Testing a TV? Open this page in the TV’s web browser, or connect a laptop over HDMI, move the browser window to the TV and start the test there.
How many dead pixels are acceptable?
There’s no single rule. Most manufacturers publish a pixel policy, often based on the ISO 9241-307 standard (the successor to ISO 13406-2), which sets how many always-bright, always-dark and sub-pixel faults are allowed per million pixels. A few faulty pixels can be “within spec”, while some brands replace a screen for even one bright pixel under warranty.
If you find faults on a new screen, take a close-up photo on the black and white screens, note where they are, and contact the retailer while you’re still within the return period — usually quicker than a warranty claim. Check the exact policy for your model on the manufacturer’s website.
About this dead pixel test
This free online dead pixel test runs entirely in your browser. It simply draws solid colours on your screen, so there’s nothing to download, no permission to grant, and nothing leaves your device.
Use it on monitors, laptops, TVs, tablets and phones with LCD, IPS, VA, OLED or mini-LED panels, in Chrome, Edge, Firefox, Safari or Samsung Internet. It uses true full screen wherever the browser allows it. Found a pixel stuck on a colour? Try the Stuck Pixel Fixer next.
Frequently asked questions
How do I do a dead pixel test?
Clean your screen, click Start full-screen test and step through white, black, red, green, blue and the other colours. Look for any dot that doesn’t match the colour on screen, and use a magnifier or your phone camera to check anything suspicious.
How can you tell if you have a dead pixel?
A dead pixel stays black on every colour and is easiest to see on the white screen. A dot that glows red, green, blue or white on the black screen is a stuck or hot pixel instead, and dust moves when you wipe the screen.
Do dead pixels spread?
Usually not. A dead or stuck pixel is a fault in that one pixel and normally stays the same. If new faulty pixels keep appearing, or you see lines or patches, the panel or its connection may be failing, so contact the manufacturer while it’s under warranty.
How many dead pixels are acceptable?
It depends on the manufacturer’s pixel policy, which is often based on ISO 9241-307 and allows a small number of faulty pixels per million depending on the screen’s class. Check the policy for your model, and report faults on a new screen while you can still return it.
Can a dead pixel be fixed?
A truly dead pixel rarely comes back, because its transistor or connection has failed. Stuck and hot pixels sometimes can be revived — run the Stuck Pixel Fixer over the spot for 10 to 20 minutes.
Does the dead pixel test work on phones and TVs?
Yes. It works in any modern browser on phones, tablets, laptops, monitors and smart TVs. Tap or swipe to change colours on a touchscreen, or use the arrow keys on a TV remote or keyboard.