Dead Pixel Test – Free Online Monitor & Screen Checker
Test your monitor, laptop, smartphone, or TV screen for dead pixels and stuck subpixels in seconds. Launch an edge-to-edge full-screen color check directly in your browser with zero downloads, zero registration, and complete privacy.
Runs 100% locally in your web browser. Strict client-side execution with zero data storage or telemetry.
How to Test a Screen Using Solid Colors
Every digital display creates images by combining red, green, and blue (RGB) subpixels. Full-screen solid colors isolate individual subpixel channels to make defective transistors immediately visible.
⚪ Pure White Test
Lights all RGB subpixels simultaneously at 100% intensity. Genuinely dead pixels appear as distinct, unlit dark spots. Also ideal for spotting surface dust and dirty panel smudges.
⚫ Pure Black Test
Commands all subpixels to shut off. Exposes bright stuck subpixels, hot white pixels, IPS glow, and perimeter backlight bleed leaking through bezel edges.
🔴 Pure Red Test
Isolates the red subpixel channel. Any dark spot indicates a dead red subpixel, while an unwanted green or blue glow indicates cross-channel voltage leaks.
🟢 Pure Green Test
Human vision is most sensitive to green wavelengths. This slide quickly reveals malfunctioning green subpixels that often cause eye fatigue or visible text fringing.
🔵 Pure Blue Test
Isolates the blue subpixel channel. On OLED screens, blue subpixels wear faster over time; this background checks for differential degradation and dead blue subpixels.
🟡 Secondary Colors (CMY)
Yellow (R+G), Cyan (G+B), and Magenta (R+B) combine subpixel pairs. If a subpixel fails, the color balance tilts, pinpointing partial subpixel defects instantly.
Step-by-Step Display Inspection Procedure
Follow these four simple steps to thoroughly inspect any monitor, laptop, or mobile screen for defective subpixels:
Clean Your Screen
Turn off your display and gently wipe the panel using a clean, dry optical microfiber cloth. Never spray liquids directly onto modern screen coatings. Cleaning first ensures dust or smudges aren't mistaken for dead subpixels.
Prepare Room & Brightness
Dim ambient room lighting to eliminate glare and reflections. Set your screen brightness to 100% and temporarily turn off True Tone, Night Light, or blue-light filters to view accurate, unadjusted color channels.
Enter Fullscreen Mode
Click 'Start Dead Pixel Test' or press F11 to remove browser address bars and OS taskbars. True edge-to-edge fullscreen ensures corner and bezel boundary pixels are fully exposed.
Cycle Colors & Inspect
Press the Spacebar or tap the screen to step through solid White, Black, Red, Green, Blue, and Yellow. Position your eyes 18–24 inches away and scan methodically across all four quadrants.
Dead Pixels vs. Stuck Pixels vs. Hot Pixels
Screen defects behave differently depending on the transistor state. Understanding the defect type helps determine whether it can be stimulated or requires a warranty claim.
Dead Pixel
An unpowered subpixel transistor that fails to receive current. It stays permanently black across white and light backgrounds. Learn more about what is a dead pixel and how subpixels fail.
Permanent Hardware DefectStuck Pixel
A subpixel locked continuously in an open electrical state, displaying static red, green, or blue instead of changing with video content.
May Respond to Color CyclingHot Pixel
All three RGB subpixels receive continuous maximum electrical voltage, shining as a sharp white pinpoint against dark backgrounds.
Qualifies Under Warranty Thresholds| Defect Type | Visual Appearance | Electrical State | Best Detection Screen | Software Fixable? |
|---|---|---|---|---|
| Dead Pixel | Solid black dot | Unpowered (Off) | Pure White, Yellow, Cyan | No (Hardware Failure) |
| Stuck Pixel | Static red, green, or blue dot | Continuous single-subpixel power | Pure Black or opposite colors | Sometimes (Rapid RGB cycle) |
| Hot Pixel | Bright white pinpoint | All RGB subpixels fully powered | Pure Black, Dark Gray | No (Hardware Panel Defect) |
Learn more in our guide on Dead Pixels vs. Stuck Pixels.
Practical Instructions for Desktop, Laptop, and Mobile Users
Screen sizes, pixel densities, and browser behaviors differ across devices. Follow these device-specific inspection recommendations:
Desktop Monitors (1080p, 1440p, 4K)
- Dim ambient room lighting to eliminate screen reflections.
- Press F11 on Windows or Ctrl+Cmd+F on Mac to enter true fullscreen mode.
- Inspect from 18–24 inches away, checking center, outer bezels, and corners.
- Shift viewing angles slightly to separate harmless IPS glow from permanent panel defects.
Laptops & MacBooks
- Test immediately upon unboxing before retailer 14–30 day return windows close.
- Inspect for keyboard pressure marks, which look like faint white bruises near the screen center.
- Gently wipe the glass with a dry microfiber cloth before running the test.
- Set screen brightness to 100% to easily spot unlit subpixels.
Smartphones & Tablets (iOS / Android)
- Disable True Tone, Night Shift, or Eye Comfort Shield before testing.
- Tap anywhere on the touchscreen to advance through colors.
- Rotate between portrait and landscape to check beneath camera notches and dynamic islands.
- Inspect OLED panels on dark gray to check for vertical banding and burn-in.
What This Test Can and Cannot Detect
Clear, honest expectations about browser-based display testing capabilities:
✓ What the Test CAN Detect
- Dead Subpixels: Completely unpowered subpixel transistors showing as black pinpoints on light backgrounds.
- Stuck Subpixels: Subpixels locked on static red, green, or blue colors.
- Hot Pixels: Permanently illuminated white dots shining against dark backgrounds.
- Backlight Bleed & IPS Glow: Uneven light leakage around bezel corners on LCD displays.
- Near-Black Banding: Grayscale stepping and non-uniformity across OLED and VA panels.
- Surface Dust vs. Pixel Defects: Visual comparison under clean solid color lighting.
✗ What the Test CANNOT Detect
- Internal Glass Micro-Cracks: Internal physical fractures behind panel substrate layers before subpixels disconnect.
- GPU Driver Bugs: Artifacts generated by corrupted graphics card drivers outside browser viewport rendering.
- Permanent Hardware Repairs: Browser tools cannot electronically repair physically dead transistors or damaged ribbons.
- Automated Camera Inspections: The tool presents standard optical test patterns; visual inspection by human eye is required.
Display Diagnostic Tools Directory
Select a specialized test below to inspect pixel integrity, backlight uniformity, motion behavior, or color depth.
Free Dead Pixel Test
Fullscreen pure RGBW color backgrounds to find dead, stuck, and hot pixels across all display types.
Stuck Pixel Test & Fixer
Detect pixels frozen on static colors and run high-frequency RGB noise stimulation to revive subpixels.
Fix Stuck Pixels →Complete Screen Test
Step-by-step diagnostic workflow checking pixels, backlight bleed, gradient banding, resolution, and refresh rate.
Run Complete Test →
Backlight Bleed & IPS Glow
Fullscreen pure black tests to spot edge light leakage vs IPS viewing-angle glow vs OLED uniformity.
Test Backlight Bleed →
Screen Resolution & Scaling
Verify reported native screen resolution, viewport size, Device Pixel Ratio (DPR), and OS scaling factors.
Check Resolution →
Refresh Rate (Hz) & Motion
Estimate display refresh rate (60Hz, 120Hz, 144Hz, 240Hz, 360Hz+) with frame timing analysis.
Measure Refresh Rate →
Grayscale Gradient Test
Inspect 256-level black-to-white transitions, color banding, shadow crush, and gamma stepping.
Test Grayscale →Webcam & Mic Test
Test camera video stream, FPS, mirror modes, and microphone input level indicators securely client-side.
Test Camera & Mic →Test Displays by Device Type
Tailored diagnostic instructions and full-screen color patterns optimized for specific hardware platforms.
Laptop Screen Test
Check Windows laptops, MacBooks, and Chromebooks for dead pixels and keyboard pressure spots.
Test Laptop Screen →Desktop Monitor Test
Inspect 1080p, 1440p, 4K, and Ultrawide IPS, VA, and OLED desktop displays.
Test Monitor →TV Screen Test
Test 4K and 8K Smart TVs (Samsung, LG, Sony, TCL) via built-in browser or HDMI connection.
Test TV Screen →Phone Screen Test
Tap-to-cycle fullscreen testing for iPhone, Samsung Galaxy, Google Pixel, and Android screens.
Test Phone Screen →Tablet Screen Test
Inspect iPad Pro, iPad Air, Galaxy Tab, and Surface tablets for dead subpixels and pressure marks.
Test Tablet Screen →Display Guides & Warranty Policies
In-depth guides on screen technology, manufacturer pixel warranties, and display troubleshooting.
What Causes a Dead Pixel? →
Explore physical, electrical, and thermal factors that cause subpixel transistors to fail during manufacturing or daily use.
Read Guide →How to Fix a Stuck Pixel →
Step-by-step instructions on using software noise boxes and rapid RGB color cycles to unstick subpixels safely.
Read Guide →Manufacturer Dead Pixel Warranties →
Understand ISO 9241-307 class guidelines and check return policies from Dell, LG, ASUS, Samsung, and Apple.
Read Guide →Screen Inspection Checklist →
Printable 9-point display checklist to verify any new or secondhand monitor before your purchase return window expires.
Read Guide →Display Inspection Before Buying a Monitor (or During Return Windows)
Why inspecting your display within the initial return window is the single most important step for consumer protection:
1. Retailer Return Windows vs. Manufacturer Warranties
Most electronics retailers (Amazon, Best Buy, B&H, Micro Center) provide an initial 14-to-30 day return or replacement window. If you spot even one dead pixel or stuck subpixel during this period, you can return or exchange the monitor immediately without disputing warranty technicalities.
Once the return window closes, you fall under manufacturer warranty rules, which typically follow ISO 9241-307 Class II standards requiring 3 to 5 defective subpixels before qualifying for replacement. Always run this test on day one.
2. What to Do If You Discover a Pixel Defect
Step 1: Identify the Defect. If the dot is solid black on white, it is a dead pixel (unpowered transistor). If it glows red, green, or blue, it is a stuck subpixel. Try running our Stuck Pixel Fixer for 15–20 minutes to stimulate the crystal.
Step 2: Document with Photos. Turn off room lights, show pure white and black screens, and take close-up photos with your phone camera as dated evidence.
Step 3: Exchange Early. Contact your store for a replacement immediately. Review specific brand thresholds in our Manufacturer Dead Pixel Warranties Guide.
Frequently Asked Questions
Common questions regarding dead pixels, stuck subpixels, screen testing methods, and warranties.
Click 'Start Dead Pixel Test' or select any color button to enter edge-to-edge fullscreen mode. Gently clean your screen with a microfiber cloth, then cycle through solid backgrounds (White, Black, Red, Green, Blue, Cyan, Magenta, Yellow) using the Spacebar, Arrow keys, or screen taps to inspect every zone for dark dots or frozen color subpixels.
A dead pixel is a defective display subpixel whose thin-film transistor (TFT) has completely failed to receive electrical power, leaving it permanently dark and appearing as a solid black dot across bright backgrounds. To learn more about subpixel mechanics, causes, and manufacturer replacement rules, read our complete guide on what is a dead pixel.
A dead pixel is an unpowered subpixel transistor that remains completely dark (solid black) across all bright backgrounds and cannot be revived by software. A stuck pixel is a transistor frozen in an open state that stays locked on a single color (such as pure red, green, or blue), which may sometimes respond to rapid color cycling.
Some stuck subpixels may recover when stimulated by rapid RGB color strobing or software noise boxes, which encourage the liquid crystal material to reset. Genuinely dead pixels caused by physical transistor failure cannot be repaired by software and require hardware panel replacement.
This test detects dead pixels, stuck subpixels, hot pixels, backlight bleed, IPS glow, and screen color uniformity variances. It cannot detect internal glass micro-fractures, hardware GPU artifacting outside the browser canvas, or physical delamination that has not yet affected subpixel illumination.
Yes. The test runs 100% in your web browser across Windows laptops, MacBooks, Chromebooks, iPhones, Android phones, iPads, tablets, and Smart TVs. On mobile devices, tap anywhere on the screen to advance through colors.
Photograph the defect against solid backgrounds as proof. If your display was purchased within the retailer's 14-to-30 day return period, request an immediate return or replacement, as retailer exchange policies are much easier to claim than manufacturer warranty defect thresholds.