Dead Pixel Checker

What This Dead Pixel Test Does

A dead pixel test fills your entire screen with a single solid color to reveal any pixel that fails to display that color correctly — showing up as a small dot of a different color against the uniform background. This tool cycles through six colors (Red, Green, Blue, White, Black, Gray) using browser full-screen mode. Each color is designed to reveal a specific defect type: red, green, and blue screens reveal stuck sub-pixels of opposing colors; white maximally lights all sub-pixels and reveals any that are dead (staying black); black reveals hot pixels (always-on bright dots) and backlight bleeding; gray reveals luminance uniformity issues and subtle banding. Running all six tests takes under two minutes and covers every pixel defect type defined in the ISO 9241-302 standard.

Who Uses a Dead Pixel Test and Why

How to Run the Dead Pixel Test

1. Dim the room. Turn off or dim surrounding lights. Ambient reflections on the screen surface make pixel defects harder to spot.
2. Clean the screen. Wipe the display with a microfiber cloth — dust or smudges can be mistaken for dead pixels during testing.
3. Click "Start Full-Screen Test". This enters browser full-screen mode, eliminating the taskbar and browser UI.
4. Cycle through all 6 colors. Click, press spacebar, or use arrow keys to advance through Red → Green → Blue → White → Black → Gray.
5. Scan slowly. Move your gaze methodically across the entire screen during each color pass. Pay extra attention to corners and edges where defects cluster most frequently.
6. Note and photograph any defects. If you find a suspected dead pixel, take a photo with another device as documentation.

ISO Pixel Defect Classes — How Many Dead Pixels Are Acceptable?

The ISO 9241-302 standard defines four pixel defect tolerance classes for display panels. Most consumer monitors are Class II, which allows up to 2 fully dark (dead) pixels and 2 fully bright (hot) pixels before the panel is considered defective. Class I panels — found on professional reference monitors and high-end medical displays — allow zero defects of any type.

Source: ISO 9241-302:2008. Values are per million pixels. Check your monitor's product specification or warranty document for its declared defect class before filing a warranty claim.

Dead vs. Stuck vs. Hot Pixels — Technical Explanation

Limitations of This Test

Frequently Asked Questions

What is a dead pixel?

A dead pixel is a display sub-pixel whose transistor has permanently failed, leaving it in an always-off state. On LCD screens, this means no backlight reaches that spot, making it appear as a small black dot on any background. On OLED screens, a dead pixel is an organic LED cell that no longer emits light. Dead pixels are distinct from stuck pixels and are generally considered a permanent hardware defect.

What is the difference between a dead pixel, a stuck pixel, and a hot pixel?

A dead pixel is always black — no power reaches the sub-pixel. A stuck pixel is permanently lit in one of the three sub-pixel colors (red, green, or blue) — it receives constant power. A hot pixel appears as a consistently bright white dot — all three sub-pixels are permanently on. Dead pixels are most visible on bright white backgrounds; stuck pixels are most visible on solid single-color backgrounds; hot pixels are most visible on dark backgrounds. This tool's multi-color test cycle is designed to reveal all three types.

How do I use the dead pixel checker?

Click'Start Full-Screen Test' to enter full-screen mode. Click anywhere on the screen, press the spacebar, or use the arrow keys to cycle through the test colors: Red, Green, Blue, White, Black, and Gray. Inspect the entire screen carefully during each color pass, paying close attention to edges and corners where defects are most commonly found. Press Escape to exit full-screen mode.

Why are there 6 test colors and what does each reveal?

Red, Green, and Blue screens reveal stuck pixels of the opposite colors — a green stuck pixel stands out vividly against a red background. White reveals dead (black) pixels most dramatically. Black (dark screen) reveals hot pixels and bright stuck pixels. Gray reveals subtle luminance uniformity issues and backlight bleeding that solid colors can mask. Using all six maximizes the chance of spotting any defect type.

Can stuck pixels be fixed?

Sometimes. Stuck pixels (which receive power but are frozen in one color) occasionally respond to: (1) running a rapid color-cycling program (JScreenFix-style pixel exercise) for 10–30 minutes, which can re-activate the liquid crystal layer; (2) gentle pressure with a soft cloth while the screen is on, applied carefully to the stuck area. Dead pixels — which receive no power at all — are generally permanent and cannot be fixed without a screen replacement.

How many dead pixels are acceptable on a new monitor?

ISO standard 13406-2 (now superseded by ISO 9241-302) defines pixel defect tolerance classes. Class II monitors (most mid-range consumer displays) allow up to 2 fully dead pixels, up to 2 fully bright pixels, and up to 5 partially defective sub-pixels per million pixels before being considered defective. Class I (professional displays) allows zero dead pixels. Check your monitor's warranty terms — many manufacturers offer zero-dead-pixel guarantees on premium models.

Does this test work on OLED and AMOLED displays?

Yes. The solid-color test works on all display technologies — LCD, IPS, VA, TN, OLED, AMOLED, and QLED. The failure modes differ (OLED can develop burn-in in addition to dead pixels), but the visual detection method is the same: a defective pixel shows up as an anomalous dot against a uniform solid color background.

Can I use this to check a monitor before buying it?

Absolutely. This is one of the most common use cases. Before purchasing a used monitor or accepting a new monitor delivery, run the full dead pixel test. On a used monitor purchase, document the test with a phone camera photo as evidence for price negotiation or returns. On a new monitor, test within the return window — typically 14–30 days — so you have options if defects are present.

Does this test show backlight bleeding?

Yes. The black test screen is the best way to check for backlight bleeding (also called IPS glow), which appears as a brighter glow or halo near the corners and edges of the display when viewed in a dark room. This is common on IPS LCD panels and is separate from dead pixels. Severe backlight bleed on a new monitor is grounds for a return under most manufacturer policies.

Is this test safe for my screen? Will it cause burn-in?

The test is safe and does not cause burn-in on LCD screens. On OLED and AMOLED displays, extended display of a static solid color (especially white, which lights all sub-pixels at maximum) could theoretically contribute to burn-in over a very long period. However, running a 5-minute dead pixel check is not sufficient exposure to cause OLED burn-in — this concern applies to static content displayed for hours or days, not short diagnostic tests.