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SPCXTools

Dead Pixel Test

Fill your screen with solid colours to spot dead pixels, stuck pixels and backlight bleed.

Runs locally — files never leave your device

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How to use Dead Pixel Test

  1. 1Clean your screen with a soft, dry cloth so dust isn't mistaken for a bad pixel.
  2. 2Click Start full-screen test (or any colour swatch) to fill the whole screen.
  3. 3Click, press Space or the arrow keys to cycle through black, white, red, green, blue and other colours.
  4. 4Look carefully across the screen for dots that don't match the colour. Double-click or press Esc to exit.

Check your screen for dead and stuck pixels

Every LCD and OLED screen is made of millions of tiny pixels, each with red, green and blue sub-pixels. Sometimes a pixel fails and stays black or stuck on one colour. On busy images these faults are almost invisible, but on a solid colour they stand out immediately. This dead pixel test fills your entire screen with pure colours so you can inspect it properly — ideal for a new monitor, a laptop you are about to buy second-hand, or a phone you want to return.

How to run a thorough test

  1. Clean the screen first, so dust and smudges aren't confused with defects.
  2. Turn the brightness up and, if possible, dim the room.
  3. Go full screen and step through every colour.
  4. Scan systematically — divide the screen into areas and check each one, including the edges and corners. A magnifying glass or your phone's camera zoom can help on high-resolution displays.
  5. Note the position of any fault, and take a photo if you plan to claim a replacement.

What each colour reveals

Screen Look for
Black Stuck or hot pixels (bright dots), backlight bleed, glow
White Dead pixels (dark dots), uneven brightness, dirt
Red, green, blue Faulty sub-pixels — a dot missing one of these colours
Cyan, magenta, yellow Faulty sub-pixel combinations
Gray Banding, uniformity problems, "dirty screen effect"

Dead, stuck or just dust?

A real pixel fault is perfectly sharp, square and stays in exactly the same place when you look from different angles. Dust or a scratch on the surface looks softer, may cast a tiny shadow, and can be wiped away. If a coloured dot changes colour from screen to screen, it is likely a stuck sub-pixel rather than a fully dead pixel.

Before you return a monitor

Read the manufacturer's pixel policy: many follow ISO 9241-307 and only accept returns above a certain number of defects. Retailers often have more generous return windows than manufacturer warranties, so test new displays as soon as they arrive.

You can also check your display's resolution with Screen Resolution and its refresh rate with the Refresh Rate Test.

Frequently asked questions

What is the difference between a dead pixel and a stuck pixel?
A dead pixel stays black on every colour because it receives no power — it is most visible on the white screen. A stuck pixel is permanently lit in one colour (red, green, blue, or a mix) and shows up best on black or on a contrasting colour. A hot pixel stays white on every background.
Can stuck pixels be fixed?
Sometimes. Stuck pixels can occasionally be revived by rapidly flashing colours over them for a while, or by gently massaging the area with a soft cloth while the screen is off. Dead pixels usually cannot be repaired. Never press hard on an LCD panel.
How many dead pixels are acceptable?
It depends on the manufacturer's pixel policy, usually based on the ISO 9241-307 standard. Many brands only replace a monitor if there are several dead pixels or one in the centre of the screen; premium models may offer a "zero bright dot" guarantee. Check the policy and test new screens within the return period.
What is backlight bleed?
On LCD screens, light can leak around the edges of the panel, creating brighter patches in the corners on a black image. Use the black screen in a dark room to check it. Some bleed is normal on IPS panels; strong, uneven bleed may qualify for a replacement. OLED screens don't have backlight bleed.
Does this test work on phones and TVs?
Yes. Open the page on any device with a browser. On phones, tap to change colours. On a TV, open the page in the TV's browser or cast a browser tab to it.

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