How to Test for Dead Pixels
- Clean the screen with a dry microfibre cloth, so dust isn’t mistaken for a defect.
- Press Start full-screen test. The screen fills with black.
- Click (or press → or Space) to step through black, white, red, green, blue, cyan, magenta, yellow and grey. Right-click or ← goes back.
- Look slowly across the whole screen on each colour, including the corners and edges. Viewing from about 30–50 cm works best.
- Press Esc to exit.
What to Look For
| What you see | On which colours | Likely defect |
|---|---|---|
| Black dot | All except black | Dead pixel |
| Bright dot | Black | Hot (stuck-on) pixel |
| Red, green or blue dot | Most colours | Stuck subpixel |
| Dot of the wrong colour | Only one colour | Partially stuck subpixel |
| Soft, blurry speck | All | Dust or debris, not a pixel |
The black screen reveals bright stuck pixels best. The white and grey screens reveal dead pixels best. Red, green and blue screens show which subpixel is affected.
Why Pixels Fail
Each pixel on an LCD is made of three subpixels — red, green and blue — each controlled by a tiny transistor. If a transistor fails, its subpixel stays permanently off (a dark dot) or on (a coloured dot). OLED pixels emit their own light, so a failed OLED pixel is typically dark.
Most defects exist from manufacturing, which is why testing a new monitor straight away matters. New defects can appear later from heat, pressure or physical damage.
Fixing Stuck Pixels
Stuck pixels can sometimes be revived, dead pixels very rarely:
- Wait. Some stuck pixels recover after a few days of use.
- Gentle pressure. With the screen off, press lightly over the spot through a soft cloth, then turn it on.
- Flashing colours. Playing rapidly changing colours over the pixel for 10–30 minutes can unstick it. These videos flash quickly; avoid them if you’re sensitive to flashing light.
Check Your Return Window
Most retailers and manufacturers have a strict window for returning a monitor with pixel defects. Test on the first day, take a close photo of any defect, and contact the seller before the window closes.
Frequently Asked Questions
What Is the Difference Between a Dead and a Stuck Pixel?
A dead pixel stays black on every colour because it isn't getting power. A stuck pixel stays one colour — red, green or blue — because one of its subpixels is permanently on. Stuck pixels can sometimes be fixed; dead pixels usually can't.
How Many Dead Pixels Are Acceptable?
It depends on the manufacturer's pixel policy, usually based on ISO 9241-307. Many brands only replace a monitor after several defective pixels, but premium lines often offer a zero dead pixel guarantee. Check the policy and test as soon as the monitor arrives.
Can a Stuck Pixel Fix Itself?
Sometimes. Stuck pixels occasionally recover after hours of normal use. Gently massaging the area with a soft cloth while the screen is off, or running a rapidly flashing colour video over the spot, can also help. Don't press hard — you can damage the panel.
Is It Dust or a Dead Pixel?
Dust sits on the surface and looks soft or blurry, and you can often wipe it away. A dead pixel is sharp-edged, exactly one pixel in size, and stays in the same place when you look from different angles.
Does This Work on a Phone or TV?
Yes. Open the test in the device's browser and use full screen. On phones, tap to change colour. For a TV, open it in the TV's browser or cast a browser tab.
Related Tests
- Monitor Ghosting TestWatch blocks move across three backgrounds and look for trails, blur or bright halos behind them.
- Monitor Refresh Rate TestFind out how many times per second your screen is really refreshing — and whether your high-refresh monitor is stuck at 60 Hz.
- PPI CalculatorEnter a screen's resolution and size to see its pixel density, dot pitch and how close you can sit before pixels become visible.
Last updated · Part of our display tests.