About this tool

A dead pixel test fills your entire screen with a single solid color so any pixel that isn't behaving like its neighbors stands out immediately. This tool gives you eight full-screen swatches — Black, White, Red, Green, Blue, Yellow, Cyan, and Magenta — plus a fullscreen mode and an auto-cycle sweep that walks through all eight for you, so you don't have to click back and forth manually while you scan the panel.

Different pixel faults show up against different backgrounds. A dead pixel (permanently unlit) is easiest to spot against a bright fill like White or Blue. A stuck pixel (locked to one color) stands out most against Black or a fill that contrasts with whatever color it's stuck on. A bright pixel is most visible against Black. Cycling through all eight colors — rather than checking just one or two — is what actually gives you confidence you've covered the panel properly.

Key features

• Eight full-screen color swatches: Black, White, Red, Green, Blue, Yellow, Cyan, Magenta
• True fullscreen mode via the Fullscreen API, with the toolbar and hints hidden so the color fills the entire display
• Auto Cycle mode with selectable per-color duration (2s / 5s / 10s), Start / Pause / Resume / Stop controls
• Full keyboard control: number keys 1–8 for colors, F for fullscreen, Space to play/pause the cycle
• Manually clicking a swatch instantly stops an active auto cycle, so you're never fighting the timer

Why use it

• Check a new or secondhand monitor, laptop, or phone screen for dead, stuck, or bright pixels before a return window closes
• Spot backlight bleed or IPS glow around the edges of a panel on a Black fill
• Verify a manufacturer's dead-pixel policy claim against what you're actually seeing

Why monitor testing matters

Manufacturing defects in LCD and OLED panels are common enough that most vendors publish an explicit "acceptable dead pixel count" policy rather than guaranteeing a perfect panel. The only way to know whether your specific unit falls inside or outside that policy is to actually look — and a single glance at your desktop background rarely reveals a stuck or dead pixel sitting quietly inside a similarly-colored icon or window. A deliberate, full-screen, color-by-color sweep is the only reliable way to catch these early, while you still have a return or warranty window open.

Tips for accurate results

• Run the test in fullscreen, in a dim room, at or near maximum brightness — glare and reflections hide faint stuck or dead pixels.
• Clean the screen with a dry microfiber cloth before testing — dust specks and smudges are easy to mistake for a dead pixel, and vice versa. Avoid liquids or harsh chemicals on the panel.
• Sit close enough to inspect the panel directly, and scan it in sections rather than trying to take in the whole screen at once.
• Check every one of the eight colors — a stuck pixel that's invisible on White may be obvious on Black, and vice versa.

Frequently asked questions