During the test: click / tap / arrow keys change color • Esc exits. Clean the screen first – dust looks exactly like a dead pixel.
Quick answer: Click Start fullscreen test, then click or press an arrow key to cycle through solid white, black, red, green and blue screens. A pixel that stays black on every color is dead; one glowing a fixed wrong color is stuck. Press Esc to exit.
Every LCD and OLED pixel is made of red, green and blue subpixels, and a single failed transistor leaves a dot that ignores what the screen is told to display. The only reliable way to spot one is to fill the entire screen with solid colors: white exposes dead (always-black) pixels, black exposes stuck (always-lit) ones, and pure red, green and blue isolate a failed subpixel of that color.
Run this before the return window closes on any new phone, laptop, monitor or TV – and always when buying second-hand. Wipe the screen first so you don't chase a speck of dust, look from about 30 cm away, and scan in a grid pattern across each color. The test is pure fullscreen color rendered by your own browser: nothing is downloaded or measured, and it can't harm the display.
How to check a screen for dead pixels
- Clean the screen – dust and dried droplets are the #1 false alarm.
- Click Start fullscreen test; the screen fills with solid white.
- Click anywhere (or press an arrow key / spacebar) to step through black, red, green, blue and the remaining colors.
- On each color, scan the whole screen slowly in rows, corners included.
- Press Esc to exit. Note any dot's color behaviour to tell dead from stuck.
Why use the GadgetsFocus dead pixel test?
- True fullscreen solid colors: white, black, red, green, blue, plus yellow, cyan, magenta and 50% grey.
- Works on any display – monitors, laptops, phones, tablets and TVs with a browser.
- Keyboard, mouse and touch controls for stepping through colors.
- Grey and secondary colors help reveal subtle subpixel and uniformity faults.
- Completely offline-safe – it's just your browser painting the screen.
Honest limitations
- A test can reveal faulty pixels but cannot repair them; stuck pixels sometimes recover on their own or with gentle massage techniques, dead ones don't.
- On OLED screens, black means pixels are physically off – a faint glow on black is a stuck subpixel, but slight color tinting at extreme angles is normal for the panel type.
- Browser fullscreen may keep a thin system bar on some phones (iPhone Safari) – rotate to landscape or add the page to your home screen for edge-to-edge testing.
- One or two defective pixels may be within the manufacturer's warranty tolerance – check your brand's dead-pixel policy before requesting a replacement.
Frequently asked questions
What's the difference between a dead pixel and a stuck pixel?
A dead pixel gets no power and stays black on every color – easiest to see on the white screen. A stuck pixel is locked on: it glows red, green, blue or white against the black screen. Stuck pixels occasionally recover; dead pixels are permanent.
Can a dead pixel be fixed?
Truly dead pixels can't be fixed – the transistor has failed. Stuck pixels sometimes unstick after rapid color cycling or very gentle pressure with a soft cloth on the exact spot (at your own risk, and never on OLED). If the screen is under warranty, check the maker's pixel policy first.
How many dead pixels justify a warranty replacement?
It varies by manufacturer and panel class. Many brands replace a panel with 3–5 bright/dark dots, and some premium lines guarantee zero. Check your specific brand's pixel policy – and test within the retailer's return window when standards are effectively “zero defects.”
Will this test damage or burn in my screen?
No. Displaying a solid color is the least demanding thing a screen can do. Just avoid leaving a static bright image on an OLED for hours – a few minutes of testing is completely safe.
I found a dark spot – is it definitely a dead pixel?
First rule out dust or residue by wiping gently with a microfiber cloth. A real dead pixel is perfectly sharp, exactly one pixel-grid dot, and sits in the same spot on every color. A blurry or irregular mark is dirt or, if under the glass, panel damage rather than a single pixel.
Related tools: Touch screen test · Refresh rate test · Webcam test · Color contrast checker
Last updated: July 11, 2026. Built and tested by the GadgetsFocus team on Chrome, Edge, Firefox and Safari (desktop & mobile). Everything on this page runs locally in your browser — we never see, store or transmit your files.