How the Screen Test Works
Click a Solid Color Swatch
View Fullscreen & Scan for Dead Pixels
Check Gradients for Banding
Review Display Specs Below
What is a Screen Test?
A Screen Test lets you check your monitor, laptop display, or phone screen for common visual defects like dead or stuck pixels, uneven backlight bleeding, poor color accuracy, and banding in color gradients. This free online tool displays solid full-screen colors (red, green, blue, white, black, and more) so any pixel that isn't displaying color correctly stands out clearly against a uniform background — something that's often invisible during normal, busy on-screen content.
This test is especially useful when buying a new or used monitor, laptop, or phone, checking a display after shipping/handling damage, or simply diagnosing a suspicious spot you've noticed on your screen during everyday use.
Dead Pixels vs Stuck Pixels vs Hot Pixels
| Type | What It Looks Like | Cause |
|---|---|---|
| Dead Pixel | Always black, never lights up on any color | Pixel receives no power/signal |
| Stuck Pixel | Always shows one color (often red, green, or blue) regardless of content | Sub-pixel stuck in an "on" state |
| Hot Pixel | Always appears bright white | Sub-pixel stuck fully "on" across all colors |
Stuck pixels are sometimes fixable by gently massaging the area or using pixel-fixing flicker techniques, while true dead pixels are generally permanent and require a warranty replacement or professional repair.
How to Properly Check for Dead Pixels
- Test in a dimly lit room: Dead pixels (black) are easier to spot against bright backgrounds, while stuck/hot pixels are easier to spot against black.
- View each solid color fullscreen: Cycle through red, green, blue, white, and black to check for any pixel that doesn't match its surroundings.
- Look closely at all screen edges and corners: Dead pixels can appear anywhere, but panel manufacturing defects are sometimes more common near edges.
- Take your time: A single stray pixel is easy to miss at a glance — scan the screen systematically in sections.
Checking for Backlight Bleeding and Color Banding
Beyond dead pixels, this test also helps reveal backlight bleeding (uneven light leaking around the edges of an LCD panel, most visible on the black screen in a dark room) and color banding (visible steps instead of smooth transitions in the gradient bars, which can indicate a lower-quality panel or incorrect color depth settings).
What to Do If You Find a Dead Pixel
- Check your warranty: Many manufacturers have a "dead pixel policy" allowing replacement if the count exceeds a certain threshold.
- Try pixel-fixing software or techniques: Rapid color-cycling tools can sometimes un-stick (though not un-dead) a problematic pixel.
- Gently massage the area: Very lightly pressing on a stuck pixel's location (with the screen off) can sometimes resolve stuck sub-pixels — proceed carefully to avoid damage.
- Document it early: If you just purchased the display, test immediately so you're within the return/exchange window if needed.
Frequently Asked Questions
How many dead pixels are considered "acceptable"?
This varies by manufacturer and panel class, but many consumer displays allow a small number (often 1-5) of defective sub-pixels before qualifying for warranty replacement — check your specific manufacturer's policy.
Can a dead pixel spread or get worse?
True dead pixels typically don't spread, but if you notice new pixel issues appearing over time, it may indicate a developing panel problem worth having checked professionally.
Does this test work on phone and tablet screens?
Yes, simply open this page in your phone or tablet's browser and use the fullscreen color test the same way as on a desktop monitor.
Why does my refresh rate show as an estimate?
Browsers don't provide direct access to your exact monitor refresh rate, so this test estimates it by measuring frame timing — for an exact figure, check your display settings or GPU control panel.