Your monitor is the window to your digital world. Whether you're a photographer editing images, a gamer chasing competitive advantages, or a professional who stares at screens all day, display quality matters. But how do you know if your monitor is performing at its best? Or worse—how do you catch problems like dead pixels, backlight bleed, or color inaccuracies before they ruin your work?
That's where monitor testing tools come in. I've spent years testing displays, and I've tried dozens of tools—some excellent, some terrible. This guide breaks down the best free monitor testing tools available in 2025, what they're good for, and which one you should actually use.
Quick Navigation:
- Why Test Your Monitor?
- Online Testing Tools (Best for Quick Tests)
- Desktop Software (Best for Advanced Testing)
- Mobile Apps (Best for Phone/Tablet Screens)
- Complete Testing Guide
- FAQ
Why Test Your Monitor?
Before diving into tools, let's talk about why monitor testing matters.
1. Dead Pixel Detection
Dead pixels are permanently off pixels that appear as black dots. Stuck pixels are stuck on one color (red, green, or blue). Both are manufacturing defects, but most manufacturers only replace monitors if there are multiple dead pixels in a cluster. Testing lets you catch these during the return period.
When to test: Immediately after purchasing a new monitor, or if you notice strange spots.
2. Backlight Bleed and IPS Glow
LCD monitors use backlights, and sometimes light "bleeds" through at the edges or corners, especially on dark screens. IPS panels also exhibit "IPS glow"—a whitish glow at angles. Both are normal to some degree, but excessive bleeding indicates quality control issues.
When to test: New monitors, especially IPS panels. Also if you notice uneven brightness in dark scenes.
3. Color Accuracy and Uniformity
Your screen should display colors consistently across the entire panel. Color shifts, tinting, or brightness variations indicate poor uniformity—common in budget monitors.
When to test: Before calibration, or if colors look "off" compared to other devices.
4. Response Time and Input Lag (Gaming)
For gamers, slow pixel response causes motion blur and ghosting. Input lag (delay between action and display) affects competitive play. Testing reveals if your monitor meets its advertised specs.
When to test: Setting up a new gaming monitor, or troubleshooting motion blur.
5. Burn-In Prevention (OLED Displays)
OLED monitors and TVs can suffer from permanent burn-in if static images display too long. Regular testing helps you catch early image retention before it becomes permanent.
When to test: Monthly for OLED displays with heavy static content use.
Online Testing Tools (Best for Quick Tests)
Online tools require no installation—just open a browser and start testing. Perfect for quick checks or testing displays you don't own.
1. Black Screen Tool (Our Recommendation)
Website: Black Screen Tool
Best for: Dead pixel detection, burn-in prevention, uniformity testing
What it does:
- Fullscreen solid colors (black, white, red, green, blue, yellow, orange, pink, purple)
- Dead pixel detection mode
- OLED burn-in protection with moving patterns
- Completely free, no registration
How to use:
- Visit blackscreen.cc
- Click "Fullscreen" or press F11
- Choose a color (black for dead pixels, white for backlight bleed)
- Inspect your screen carefully in a dark room
Pros: Instant access with no download, works on any device, multiple test colors, OLED protection mode, clean interface without ads, supports 4K and ultrawide monitors.
Cons: No advanced calibration features, requires manual visual inspection.
Our take: This is our tool, so I'm biased—but we built it because existing online tools were either ad-riddled or missing key features. If you need a quick way to test dead pixels or check uniformity, this is the fastest option.
Also check out: Our White Screen Test for bright pixel and uniformity testing.
2. EIZO Monitor Test
Website: eizo.be/monitor-test
Best for: Comprehensive browser-based testing
What it does:
- Dead pixel test (various color patterns)
- Color gradients and uniformity
- Response time visualization
- Viewing angle test
- Text readability test
Pros: Very comprehensive test suite, professional-grade testing, works in browser, good explanations for each test.
Cons: Interface feels dated, some tests require interpretation, no fullscreen mode on some tests.
Our take: EIZO is a professional monitor manufacturer, and their test reflects that expertise. It's more comprehensive than most online tools but less user-friendly. Great if you want to understand why you're testing, not just run tests quickly.
3. TestUFO
Website: testufo.com
Best for: Gaming monitors (motion blur, refresh rate, input lag)
What it does:
- UFO animation tests for motion clarity
- Refresh rate verification
- Ghosting and pixel response testing
- Framerate comparison tools
- VSYNC and stuttering tests
Pros: Essential for gaming monitor testing, real-time feedback on motion performance, supports high refresh rates (144hz, 240hz, 360hz), free and widely trusted.
Cons: Not useful for color accuracy or dead pixels, requires understanding of frame rates, browser performance affects results.
Our take: If you're testing a gaming monitor, TestUFO is non-negotiable. Nothing else does motion testing this well online. But for general display quality, you'll need other tools too.
4. LagOM LCD Test Pages
Website: lagom.nl/lcd-test
Best for: Color calibration and gamma testing
What it does:
- Black level and white saturation tests
- Contrast ratio testing
- Color gradient smoothness
- Gamma calibration
- Viewing angle tests
Pros: Excellent for calibration, simple, no-nonsense interface, works perfectly in browser, educational explanations.
Cons: Very basic design, no automated tools, requires understanding of calibration concepts.
Our take: LagOM is old-school but gold-standard for calibration. If you want to manually calibrate your monitor's brightness, contrast, and gamma, this is your tool. But it's not beginner-friendly.
Desktop Software (Best for Advanced Testing)
Desktop software offers more power than browser tools—automated detection, hardware calibration, and detailed reporting.
5. Dead Pixel Buddy (Windows/Mac)
Download: deadpixelbuddy.com
Best for: Automated dead pixel detection
What it does:
- Cycles through solid colors automatically
- Timer-based testing (set it and let it run)
- Stuck pixel repair mode (rapidly flashing colors)
- Screenshot capture of problem areas
Pros: Free desktop app, automated testing saves time, stuck pixel repair sometimes works, clean, simple interface.
Cons: Requires download and install, repair mode success rate is low, no color calibration features.
Our take: If you have multiple monitors or want hands-free testing, Dead Pixel Buddy is worth the download. The stuck pixel repair is a bonus—it won't always work, but it's worth trying before returning a monitor.
6. DisplayCAL + ArgyllCMS (Windows/Mac/Linux)
Download: displaycal.net
Best for: Professional color calibration
What it does:
- Hardware calibration (requires colorimeter)
- ICC profile generation
- Multi-monitor calibration
- Gamut mapping and verification
- Before/after comparison
Pros: Professional-grade accuracy, free and open-source, supports most colorimeters, industry-standard tool.
Cons: Steep learning curve, requires hardware colorimeter ($100-500+), overkill for casual users, complex interface.
Our take: This is what professionals use. If you're doing photo editing, video production, or design work where color accuracy is critical, invest in a colorimeter and learn DisplayCAL. But for 99% of users, it's unnecessary.
7. Monitor Asset Manager (Windows Only)
Download: entechtaiwan.com/util/moninfo.shtm
Best for: Monitor information and diagnostics
What it does:
- Displays full monitor specs (EDID data)
- Shows native resolution, refresh rates
- Lists supported color profiles
- Connection type and cable info
- Age and usage hours (if supported)
Pros: Free utility, extremely detailed specs, useful for troubleshooting, lightweight.
Cons: Windows only, doesn't test image quality, technical interface.
Our take: Not a testing tool per se, but incredibly useful for verifying your monitor is running at its correct specs. Found out your "4K monitor" is running at 1080p? This tool will tell you.
Mobile Apps (Best for Phone/Tablet Screens)
8. Screen Test Pro (Android)
Download: Google Play Store (free)
Best for: Android phone/tablet testing
What it does:
- Dead pixel detection
- Touch screen response testing
- Color uniformity
- Multi-touch testing
- Sensor diagnostics
Pros: Comprehensive mobile testing, free version is feature-complete, useful for diagnosing phone issues.
Cons: Android only, some ads in free version.
9. Display Tester (iOS)
Download: Apple App Store (free)
Best for: iPhone/iPad screen testing
What it does:
- Solid color screens
- Dead pixel detection
- Touch response testing
- True Tone verification
Pros: Clean iOS interface, supports ProMotion displays, free.
Cons: Limited compared to Android options, can't disable iOS overlays completely.
Complete Monitor Testing Guide
To test a new monitor thoroughly in under 30 minutes.
Step 1: Dead Pixel Test (5 minutes)
Tool: Black Screen Test or Dead Pixel Buddy
Process:
- Clean your screen gently (dust can look like dead pixels)
- Display solid black in fullscreen
- In a dark room, look for bright spots
- Switch to white—look for dark spots
- Test red, green, blue individually (catches stuck pixels)
- Inspect closely at normal viewing distance
What to look for:
- Dead pixel: Permanently black dot on white screen
- Stuck pixel: Bright red/green/blue dot on black screen
- Hot pixel: Extra-bright white dot
Action: If you find 3+ dead pixels or 1+ in the center, consider returning (check manufacturer policy).
Step 2: Backlight Bleed Test (5 minutes)
Tool: Black Screen Tool
Process:
- Display fullscreen black
- Turn off room lights (complete darkness)
- View monitor straight-on from normal distance
- Look for bright spots at edges/corners
- Take a photo with phone (camera exaggerates it)
- Compare photo to what you see naturally
What to look for:
- Edge bleed: Bright areas at screen edges
- Corner bleed: Bright spots at corners
- Clouding: Uneven brightness patches in center
Action: Some bleed is normal on IPS panels. If it's visible in normal use (not just pure black in darkness), it's excessive.
Step 3: Uniformity Test (5 minutes)
Tool: Black Screen Tool (white and gray)
Process:
- Display fullscreen white
- Normal room lighting
- Look for color tinting (yellow, pink, blue areas)
- Display 50% gray (use White Screen at 50% brightness)
- Check for brightness variations
What to look for:
- Color shifts across the panel
- Darker or brighter zones
- Vertical/horizontal banding
Action: Perfect uniformity is rare. If differences are visible in normal content, it's a problem.
Step 4: Color Gradient Test (5 minutes)
Tool: LagOM LCD Test or EIZO Monitor Test
Process:
- Run gradient tests (black to white, color gradients)
- Look for banding (visible steps instead of smooth transitions)
- Check all primary colors (RGB)
What to look for:
- Smooth transitions (8-bit) vs banding (6-bit + dithering)
- Color accuracy
Action: Heavy banding indicates a lower-quality panel (6-bit vs 8-bit).
Step 5: Motion Test (Gaming Monitors Only) (5 minutes)
Tool: TestUFO
Process:
- Run UFO ghosting test at your monitor's max refresh rate
- Enable different pixel response settings (Overdrive)
- Look for trails behind the UFO
- Test multiple framerates
What to look for:
- Minimal ghosting/trailing
- No inverse ghosting (overshoot artifacts)
- Smooth motion
Action: Adjust overdrive settings for best balance.
Step 6: Text Clarity Test (5 minutes)
Tool: LagOM Text Test or any webpage
Process:
- Display text at various sizes
- Check subpixel rendering (RGB vs BGR)
- Look for color fringing around text
What to look for:
- Sharp, clear text
- No rainbow fringing
- Correct subpixel order
Action: Adjust ClearType settings on Windows if needed.
Tool Comparison Chart
| Tool | Type | Best For | Free | Skill Level | |------|------|----------|------|-------------| | Black Screen Tool | Online | Dead pixels, uniformity, quick tests | Yes | Beginner | | EIZO Monitor Test | Online | Comprehensive online testing | Yes | Intermediate | | TestUFO | Online | Gaming/motion testing | Yes | Intermediate | | LagOM LCD Test | Online | Calibration | Yes | Advanced | | Dead Pixel Buddy | Software | Automated dead pixel detection | Yes | Beginner | | DisplayCAL | Software | Professional calibration | Yes* | Expert | | Monitor Asset Manager | Software | Specs verification | Yes | Intermediate |
*DisplayCAL is free but requires hardware colorimeter ($100+)
Which Tool Should You Use?
For most users (quick testing):
- Black Screen Tool - Dead pixels and uniformity
- TestUFO (if gaming) - Motion performance
- Done
For professionals (accurate color):
- DisplayCAL with colorimeter - Full calibration
- LagOM LCD Test - Manual verification
- Black Screen Test - Dead pixel check
For new monitor inspection (pre-return window):
- Black Screen Test - Dead pixels, backlight bleed
- EIZO Monitor Test - Comprehensive check
- TestUFO (gaming) - Motion performance
- Dead Pixel Buddy - Stuck pixel repair attempt
For troubleshooting issues:
- Monitor Asset Manager - Verify specs/settings
- Black Screen Tool - Identify problem visually
- Manufacturer support - RMA if defective
Frequently Asked Questions
Can online tools damage my monitor?
No. Displaying solid colors or patterns is completely safe. OLED burn-in concerns are only relevant if you leave static images on for hours/days—testing tools that cycle colors actually prevent burn-in.
How many dead pixels are acceptable?
This depends on the manufacturer's policy. Most allow 3-5 dead pixels for a warranty replacement, but some premium brands (like Dell UltraSharp) have zero-dead-pixel guarantees. Personally, I find even 1 dead pixel in the center unacceptable and return monitors immediately.
Do I need a colorimeter for accurate color?
For professional color-critical work (photo editing, video grading, design), yes. For gaming, general use, or even amateur photography, no—your eyes and free tools are sufficient. Colorimeters cost $100-500+ and require learning calibration software.
Why does my monitor look different than my phone?
Different displays use different panel technologies (IPS, OLED, VA), color spaces (sRGB, DCI-P3, Adobe RGB), and calibrations. Phones often boost saturation for "punchier" colors. Neither is "wrong"—they're just different. If color accuracy matters, calibrate both to the same standard (usually sRGB).
Can stuck pixels be fixed?
Sometimes. Tools like Dead Pixel Buddy's rapid color flashing mode can unstick stuck pixels by exercising the liquid crystals. Success rate is maybe 20-30% in my experience. Dead pixels (completely off) cannot be fixed and require monitor replacement.
How often should I test my monitor?
- New monitor: Immediately, during the return period
- OLED displays: Monthly if you have heavy static content
- Regular monitors: Once a year, or when you notice issues
- Professional use: Before major projects or after calibration
Are there any tools for HDR testing?
HDR testing is more complex. TestUFO has basic HDR tests, but true HDR calibration requires specialized hardware (like Klein K10-A meters). For most users, Windows HDR calibration app or your GPU's HDR tools are sufficient.
My monitor passed all tests but still looks bad. Why?
Testing reveals hardware defects, not subjective quality. Your panel might be working "correctly" but still use a cheap TN panel with poor colors and viewing angles. Check your monitor's specs—panel type (IPS > VA > TN), color gamut (99% sRGB is good), and contrast ratio all affect subjective quality.
Use Our Free Testing Tool
Ready to test your monitor? Our Black Screen Test is the fastest way to check for dead pixels, backlight bleed, and screen uniformity. No download, no registration—just open and test.
Try it now:
- Black Screen Test - Fullscreen solid colors for dead pixel detection
- White Screen Test - Bright uniformity and backlight testing
- Black Screen Wallpaper - Download 4K test images for OLED burn-in prevention
All tools are 100% free and work on any device.
Related Resources
More Display Testing Guides
If you're experiencing specific display problems, these guides can help:
- Complete Black Screen Troubleshooting Guide - Diagnose and fix black screen issues across all devices
- OLED Burn-In Prevention Guide - Protect your OLED displays from permanent damage
- Windows Black Screen Fix - Troubleshoot Windows startup black screens
- Computer Black Screen Troubleshooting - Hardware and software diagnostic checklist
Essential Testing Tools
- Professional Black Screen Test - Dead pixel and uniformity testing
- White Screen Test - Backlight bleed and bright pixel detection
- Black Screen Chrome Extension - One-click access to display testing
- Black Screen Wallpaper Downloads - 4K test patterns for OLED protection
Final Thoughts
You don't need expensive software or professional equipment to test your monitor effectively. For 95% of users, free online tools like our Black Screen Test combined with TestUFO (for gamers) cover all essential testing needs.
The key is knowing what to test and when. Test new monitors immediately during the return period. Test OLED displays regularly if you use static content. And test any time you notice something looks "off."
Remember: A monitor is a long-term investment. Spending 30 minutes testing upfront can save you years of frustration with a defective display.
Start testing now: Free Black Screen Test
Last updated: November 19, 2025
