When Should You Test Your Screen?
Before or after buying a monitor
Dead or stuck pixels are common reasons for returns. Run this test (fullscreen) to check solid colours before the return window closes. If you find defects, see dead pixel test guide and your warranty policy.
When you notice flickering or artefacts
Flicker, banding, or odd colours can be cable, driver, or panel related. This test helps isolate the issue by cycling colours and fullscreen. For flicker fixes, see screen flickering.
When colours look wrong or washed out
Use the solid colour and gradient screens to see if the panel is uniform and if colours match expectations. Calibration and cable/driver checks often fix colour issues. Colour calibration basics can help.
When checking refresh rate or resolution
Ensure your display is set to native resolution and desired refresh rate in OS settings. This test runs in the browser at your current display mode, so you can confirm what the system is outputting.
What This Screen Test Checks
Dead pixels: Solid colours (especially black, white, red, green, blue) reveal permanently black or unresponsive pixels.
Stuck pixels: Pixels stuck on one colour show as coloured dots on black or white; they can sometimes be fixed.
Colour uniformity: Fullscreen solid colours help you spot tint or brightness variation across the panel.
Backlight and gradients: Dark screens expose backlight bleed; gradients expose banding or colour accuracy issues.
No permissions needed: The test only uses the display output; no camera or microphone access. Run in fullscreen for best coverage.
Common Screen Problems This Test Helps Diagnose
Dead pixels: Black dots on coloured backgrounds that never change. They cannot be fixed. Count and document them for warranty; see dead pixel test guide.
Flickering: Screen flickers or flashes. Often cable, refresh rate, or driver related. Test with different cables and update GPU drivers. More: screen flickering fix.
Colour or calibration issues: Colours look wrong or washed out. Check cable, resolution, and OS colour profile. Screen looks washed out and colour calibration guides can help.
Refresh rate or resolution wrong: The display may be running at a lower resolution or refresh rate than the panel supports. Set the correct mode in system display settings. Monitor refresh rate wrong has more.
Backlight bleed: Light leaking from edges on dark screens. Use the test’s dark mode to assess severity. Usually a panel characteristic rather than something software can fix.
Screen Test and Device Access
This test only uses your display output; it does not request camera or microphone. For how device access (camera, mic, and app selection) works across OS, browser, and app layers, see how device access works.
How this diagnostic works & why problems happen
How to Test Your Screen for Dead Pixels
Testing your screen for dead pixels, stuck pixels, and color accuracy is essential when purchasing a new monitor or troubleshooting display issues. Our free online screen test provides comprehensive testing tools to check your monitor's quality, identify pixel defects, and verify color accuracy—all directly in your browser.
Why Test Your Screen?
Screen testing helps you:
- Identify dead or stuck pixels before warranty expires
- Check color accuracy and calibration
- Detect backlight bleeding or uniformity issues
- Verify monitor quality after purchase
- Troubleshoot display problems
- Test multiple monitors for comparison
Understanding Dead vs Stuck Pixels
Dead Pixels
Dead pixels are permanently black and don't respond to electrical signals. They appear as black dots on colored backgrounds and cannot be fixed. Dead pixels are caused by manufacturing defects or physical damage to the screen.
Stuck Pixels
Stuck pixels are permanently lit in one color (usually red, green, or blue). They appear as colored dots on black or white backgrounds. Unlike dead pixels, stuck pixels can sometimes be repaired using pixel fixing techniques.
Step-by-Step Screen Testing Guide
- Enter Fullscreen Mode: Click "Enter Fullscreen Mode" for the most accurate test. This ensures you're testing the entire screen without browser UI interference.
- Test Solid Colors: Use the solid color mode and cycle through black, white, red, green, and blue. Look for pixels that don't match the background color.
- Use Auto Cycle: Enable auto cycle to automatically switch between colors every 2 seconds. This makes it easier to spot pixel defects.
- Check Pixel Grid: Use the pixel check mode to see individual pixels clearly. This helps identify exact pixel locations.
- Test Gradient: Use gradient mode to check for color banding and smooth color transitions.
- Document Issues: Note the location and type of any pixel defects you find. Take photos if needed for warranty claims.
How to Fix Stuck Pixels
While dead pixels cannot be fixed, stuck pixels can sometimes be repaired:
- Pixel Fixing Software: Use software that rapidly cycles colors to "unstick" pixels. Run for 10-30 minutes.
- Gentle Pressure: Turn off your monitor, wrap a soft cloth around your finger, and gently massage the stuck pixel area. Turn the monitor back on to check.
- Heat Method: Some users report success by gently warming the stuck pixel area with a warm (not hot) cloth, then cooling it.
- Pixel Unsticker Tools: Specialized tools apply rapid color changes directly to stuck pixels.
- Warranty Replacement: If stuck pixels persist and are in visible areas, contact the manufacturer for warranty replacement.
Testing Color Accuracy
Our screen test includes color accuracy testing:
- Primary Colors: Test red, green, and blue to ensure color channels work correctly
- Gradient Testing: Check for smooth color transitions without banding
- Contrast: Test black and white levels for proper contrast
- Uniformity: Check for consistent color across the entire screen
Common Screen Issues
Backlight Bleeding
Backlight bleeding appears as light leaking from screen edges, especially visible on black backgrounds. This is common in LCD monitors and may be more noticeable in dark rooms.
Color Uniformity
Color uniformity issues appear as color variations across the screen. Test with solid colors to identify areas with different tints or brightness levels.
Viewing Angles
Test your screen from different angles. Colors and brightness should remain consistent when viewed from the sides, above, or below.
Warranty and Dead Pixel Policies
Most manufacturers have dead pixel policies:
- Zero Dead Pixel Policy: Some premium monitors guarantee zero dead pixels
- Acceptable Dead Pixel Count: Many manufacturers allow 1-3 dead pixels, especially on larger screens
- Bright Pixel Policy: Stuck pixels (bright pixels) are often covered under warranty
- Clustering: Dead pixels clustered together may qualify for replacement even if under the acceptable count
- Center Screen: Dead pixels in the center of the screen are more likely to qualify for replacement
Troubleshooting Guides
- Dead pixel test guide
- Fix stuck pixels
- Screen flickering
- Screen looks washed out
- Colour calibration basics
Frequently Asked Questions
How do I test for dead pixels?
Enter fullscreen mode and cycle through solid colors (especially black, white, red, green, blue). Dead pixels appear as black dots on colored backgrounds. Stuck pixels appear as colored dots on black/white backgrounds.
What is the difference between dead and stuck pixels?
Dead pixels are permanently black and don't respond to signals. Stuck pixels are permanently lit in one color (red, green, or blue). Dead pixels cannot be fixed, but stuck pixels can sometimes be repaired with pixel fixing software or gentle pressure.
Can I fix stuck pixels?
Sometimes. Try pixel fixing software that rapidly cycles colors, apply gentle pressure with a soft cloth, or use a pixel unsticker tool. However, many stuck pixels cannot be fixed and may require screen replacement.
How many dead pixels are acceptable?
Most manufacturers consider 1-3 dead pixels acceptable, especially on larger screens. However, if dead pixels are clustered together or in the center of the screen, you may be eligible for a replacement under warranty.
Does this test work on all monitors?
Yes! Our screen test works on LCD, LED, OLED, and all monitor types. Enter fullscreen mode for the most accurate test results.
Why is my screen flickering?
Flicker is often caused by the cable, wrong refresh rate, or graphics drivers. Try another cable, set the correct refresh rate in display settings, and update your GPU drivers.
How do I test screen colour accuracy?
Use the solid colour and gradient modes in fullscreen. Check that red, green, and blue look correct and that gradients are smooth. Calibrate in OS display settings if colours look off.
Does this screen test work on laptops?
Yes. Run the test in fullscreen on the built-in display or an external monitor. The test uses whatever display is currently active.
Tips for Accurate Testing
- Use Fullscreen: Always test in fullscreen mode for accurate results
- Clean Your Screen: Clean your monitor before testing to avoid mistaking dirt for dead pixels
- Test in Dark Room: Test in a dark room to better see backlight bleeding and pixel defects
- Test All Colors: Don't just test black and white—test all primary colors
- Take Photos: Document any issues with photos for warranty claims
- Test Multiple Times: Run the test multiple times to confirm pixel defects
Ready to test your screen? Scroll up and click "Run Screen Test" to check for dead pixels, stuck pixels, and color accuracy. The test takes just minutes and helps ensure your monitor is in perfect condition.