Pixel Test Online: How to Check for Dead Pixels, Stuck Pixels & Display Defects
Buying a new monitor or laptop? The first thing you should do is run a pixel test. Dead pixels, stuck pixels, backlight bleed, and color uniformity problems are manufacturing defects that qualify for return or warranty replacement — but only if you catch them within your return window. Our free online pixel test makes comprehensive display inspection take less than five minutes.
Types of Display Defects
Dead Pixels
A dead pixel is permanently black on all colors. All three sub-pixels (red, green, blue) have failed completely. Dead pixels appear as tiny black dots on white and bright-colored screens. They cannot be fixed and indicate a hardware defect.
Stuck Pixels
A stuck pixel has one or more sub-pixels frozen in the "on" position. A stuck red pixel appears as a red dot on black screens. Stuck pixels may be fixable by rapidly cycling colors or displaying solid colors for extended periods — try our Stuck Pixel Fixer for automated repair attempts.
Hot Pixels
Related to stuck pixels, hot pixels are stuck in the "on" position and appear bright white on all test colors. Most common on camera sensors but occasionally appear on displays.
Backlight Bleed
Light leaking through the panel on dark scenes, visible as bright cloudy patches — especially in corners. Test with our Black Screen in a dark room.
How to Run a Complete Pixel Test
Step 1: Prepare Your Environment
- Clean your screen (smudges look like dead pixels)
- Dim room lights for bleed testing; moderate lighting for pixel testing
- Set monitor brightness to 50–70% (defects are most visible at moderate brightness)
- Enter fullscreen on our Pixel Test tool
Step 2: Test Each Color
Our Pixel Test cycles through essential test colors. On each color, scan the entire screen systematically:
- White — dead pixels appear as black dots
- Black — stuck pixels appear as colored dots; backlight bleed visible
- Red — green/blue stuck pixels visible
- Green — red/blue stuck pixels visible
- Blue — red/green stuck pixels visible
Spend at least 15–20 seconds per color. Move your eyes across the screen in horizontal rows rather than staring at one point — peripheral vision catches defects more easily than direct focus.
Step 3: Check Uniformity
On each solid color, look for patches that are slightly lighter or darker than the rest of the screen. Uniformity problems indicate panel quality issues that may worsen over time.
Step 4: Document Defects
Photograph or screenshot any defects you find. For return claims, manufacturers typically require evidence of the defect. Note the pixel location (describe position as percentage from top-left corner).
When to Return a Monitor
Most manufacturers consider:
- 1–3 dead pixels: Often within acceptable tolerance (varies by brand)
- 4+ dead pixels: Usually qualifies for replacement
- Any stuck pixel in the center: Often qualifies for replacement
- Significant backlight bleed: Usually qualifies, especially on premium panels
- Color banding or uniformity issues: Case-by-case, but document and report
Check your specific manufacturer's dead pixel policy before purchasing. Premium brands (Dell UltraSharp, ASUS ProArt, LG UltraFine) typically have zero-dead-pixel guarantees.
Testing Different Display Types
LCD/LED Monitors
Standard pixel testing applies. Also test for backlight bleed with black screen in a dark room.
OLED Displays
OLED can have slightly different defect characteristics. Test for dark spots (dead OLED pixels) and bright spots (stuck pixels). Also verify true black uniformity — OLED should show perfect black with no lighter patches.
Laptop Screens
Laptop screens are more prone to pressure damage during shipping. Run pixel tests immediately upon unboxing. Laptop return windows are often shorter than monitor return windows — test on day one.
Phone and Tablet Screens
Our Pixel Test works on mobile devices. Enter fullscreen and test each color. Mobile OLED screens are particularly sensitive — test before your return period expires.
Beyond Pixel Testing
A complete display check also includes:
- Gradient Test for color banding
- Refresh Rate Test for motion clarity
- Gray Screen for calibration reference
Run all tests on a new display within the first week of ownership.
Documenting Defects for Warranty Claims
When you find a defect during pixel testing, document it thoroughly before contacting the manufacturer. Take clear photos showing the defect against both white and black backgrounds. Note the pixel location as coordinates (e.g., "15% from left edge, 30% from top"). Record your monitor model, serial number, and purchase date. Most manufacturers require this information for RMA processing.
Our Pixel Test provides the standardized test colors that manufacturers expect in defect reports. Running the official test sequence demonstrates you performed due diligence before claiming a manufacturing defect.
Testing Used and Refurbished Displays
Buying used monitors from marketplace sellers? Run the complete pixel test before paying. Connect your laptop, run our Pixel Test in fullscreen, and inspect every color. Used displays may have defects the seller is unaware of — or deliberately omitting. Five minutes of testing can save hundreds of dollars on a defective panel.
Related tools: White Screen · Black Screen · Stuck Pixel Fixer · Gradient Test