Free Screen Diagnostic Tools: Test Your Display in Seconds

If your laptop, monitor, or phone screen is acting up, the fastest way to know what's actually wrong is to test it yourself before you spend money on repairs or a replacement. These four browser-based tools let you check for dead pixels, backlight flicker, unresponsive touch areas, and your screen's real refresh rate, all from a single page. No downloads, no installs, no signup. Everything runs directly in your browser and stops working the moment you close the tab.

Here's how to use each one properly.

Dead Pixel Test

A dead or stuck pixel shows up as a tiny dot that never changes color, even when the rest of the screen does. It's easy to miss during normal use because it blends into whatever you're looking at, so the trick is to remove everything else from the screen and look at pure, solid colors instead.

Tap through each color swatch (white, black, red, green, blue, and gray) one at a time, and scan the entire screen slowly, corner to corner, for any dot that stays a different color than the rest. White and black are the most revealing, since a stuck pixel is almost always locked on red, green, or blue, and that will stand out clearly against a plain background. For the most accurate result, hit the Fullscreen button before you start testing. A dim room and a screen at full brightness makes stuck pixels even easier to spot.

If you find one, note roughly where it is on the screen. A single stuck pixel near the edge is usually nothing to worry about. Several dead pixels clustered together, or ones appearing in the center of the screen, are worth mentioning if you're getting the display looked at or filing a warranty claim.

Screen Flicker Test

Flickering isn't always obvious at normal speed, especially with backlight issues caused by PWM (pulse-width modulation) dimming, which can flicker fast enough that it causes eye strain and headaches without ever looking like an obvious flicker to the naked eye.

Press Start Flicker, then use the speed slider to move between 1 Hz and 30 Hz. Start slow so you can see how the tool alternates between black and white, then gradually increase the speed. Watch for any point where the screen seems to shimmer, pulse, or where you notice a faint strobing effect even though the flicker itself looks smooth. If you're testing on a phone or laptop, try it at a few different brightness levels too, since backlight flicker on many devices only becomes noticeable below a certain brightness percentage.

A quick safety note: if you're sensitive to flashing lights or have a history of photosensitive migraines or seizures, skip this test or ask someone else to run it and describe what they see.

Touch Screen Test

This one's for phones, tablets, and touchscreen laptops. Instead of guessing whether your touch screen is responding properly, this test shows you exactly where your screen is registering (or missing) contact.

Drag your finger slowly across the entire test area, corner to corner, in a few different directions, then try tapping quickly in different spots. Every point your screen picks up leaves a small marker. What you're looking for is consistency: markers should appear smoothly along the whole path you dragged, with no gaps or dead zones. If part of the box never lights up no matter how many times you touch it, that's a strong sign of a touch-digitizer issue in that specific area, especially if it lines up with a spot where the phone may have been dropped or cracked. Try a two-finger drag as well to check whether multi-touch is registering correctly. Hit Reset any time to clear the markers and start over.

Refresh Rate Test

Your screen's refresh rate is how many times per second the image actually updates, and it directly affects how smooth motion looks when you're scrolling, gaming, or watching video. This tool measures your browser's real frame rate live and shows a moving bar so you can judge smoothness with your own eyes, not just a number.

Hit Start Measuring and let it run for at least 5 to 10 seconds so the reading has time to settle. Watch the number in the top corner along with the bar moving side to side. If the number is noticeably lower than what your screen is supposed to support, or if the moving bar looks jumpy or stutters instead of gliding, that can point to a software-level issue (like battery saver mode capping performance) or, less commonly, a hardware problem with the display itself.

A quick note before you start

None of these tools can fully diagnose hardware damage on their own, but they're a genuinely useful first step. They help you describe the exact problem clearly, whether that's to a repair shop, in a warranty claim, or just to yourself before deciding if a repair is worth it. Run through all four in order for the most complete picture of your screen's health.

Frequently Asked Questions

Do I need to download anything to use these tests?
No. Every tool on this page runs directly in your browser using standard web technology. There's nothing to install, no app, and no account required. Just open the page on the device you want to test.

Will this work on my phone, laptop, and monitor?
Yes. All six tests run on any modern browser, whether you're testing a phone screen, a laptop display, or an external monitor. For monitors, just open this page on the computer connected to that monitor and run the tests in fullscreen.

Is it safe to run the Flicker Test if I'm sensitive to flashing lights?
If you have a history of photosensitive migraines or seizures, skip the Flicker Test or have someone else run it and describe the results to you. The other five tests (Dead Pixel, Touch, Color & Contrast, Burn-in, Refresh Rate) don't involve rapid flashing and are safe to run yourself.

How accurate is the Refresh Rate Test compared to my display's spec sheet?
The tool measures your browser's actual live frame timing on that specific device, right now, rather than the manufacturer's spec sheet number. This means it reflects real-world factors like battery saver mode, background load, or driver issues that can lower your effective refresh rate below what your screen is technically capable of.

I found a dead pixel or dead zone. What should I do next?
Note where on the screen it appears and which test flagged it. A single dead pixel near the edge of the screen is usually minor, but multiple stuck pixels, a large unresponsive touch zone, or confirmed burn-in are worth mentioning directly to a repair technician or including in a warranty claim, since it saves you the back-and-forth of re-explaining the problem.

How long does it take to run the full toolkit?
About two minutes for all six tests if you're checking your screen's overall health. If you already know what's wrong (say, only the touch response feels off), you can run just that one test in under 30 seconds.

Does this tool collect or store any of my data?
No. Everything runs locally in your browser. No test results, touches, or screen data are sent anywhere or saved closing the tab clears everything.