About BadPixelTest
Free screen tests that run in your browser. No app to install, no account, and nothing to pay for.
What This Site Is
BadPixelTest is a set of screen tests that run in your browser. You open a page, press a button, and your screen fills with one flat colour at a time. That is the whole idea.
It sounds too simple to be useful, and it is the reason the tests work. A normal picture is busy. Text, photos and video are full of detail, and detail hides small faults. Fill the screen with one colour instead and anything that does not match has nowhere left to hide.
A dead pixel becomes a black dot on white. A stuck pixel becomes a coloured dot on black. Dust, scratches, uneven brightness and light leaking in at the edges all show up the same way, in seconds, with nothing to install.
Why It Exists
Most people find a screen fault by accident, months after they bought the screen, at the moment it is hardest to do anything about it.
That is a shame, because the check takes two minutes. A new monitor, a new phone, a laptop bought second hand, a screen that has just been repaired: all of them are worth two minutes while returning them is still simple.
The other half of it is the people whose screen has already gone wrong. A laptop that turned pink, a monitor with a green tint, a phone with a mark that will not wipe off. Those problems have answers, and the answers are usually simpler and cheaper than people fear. A pink laptop screen is often one worn cable. A yellow monitor is usually a setting someone turned on by accident.
So each page here does two jobs: it gives you the test, and it explains what to do about what the test finds.
What Is on the Site
The tests are grouped by what they are looking for.
Pixel Tests
For single dots that have gone wrong: dead pixels that stay dark, stuck pixels holding one colour, and bright pixels that stay lit.
Screen Tests
For the display as a whole, on a monitor, a laptop, a phone or a TV. These run through the colours and cover more than pixels.
Colour Tests
One colour at a time, each on its own page. Useful as a test, and useful as a plain background or a coloured light.
Fixing Guides
Every colour page explains why a screen turns that colour and what to try, in the order that finds the answer fastest.
How the Site Is Built
A few decisions were made early and have been kept to since. They are worth stating because they are unusual now.
There is nothing to install. No app, no extension, no download. The tests are web pages, and your browser is the only thing running them.
There is no account. Nothing asks for your name, your email or a password, because nothing here needs to know who you are.
The site loads one outside file, and that is Google Analytics, which counts visits so we know which pages are worth writing more of. Everything else is drawn in the page itself: no web fonts, no icon libraries, no advertising code, no images from other servers. The icons and the logo are hand-drawn shapes in the markup, and the type is whatever your device already uses.
That analytics script is also the only thing that leaves anything on your device — one cookie holding a random number, so that two pages read in one visit count as one person. Nothing else is stored: no saved settings, no history, no identifier of our own.
And when you download a colour as an image, the image is drawn on your device and saved from there. It is never sent anywhere.
What This Site Cannot Do
This part matters as much as the rest, because the internet is full of screen tools promising things they cannot deliver.
These tests cannot repair anything. The stuck pixel fixer flashes colour at a settled pixel, which frees some of them and does nothing at all to others. That is the honest limit of it. Nothing here can bring back a pixel whose light has failed.
They cannot measure colour accuracy. Judging whether a screen shows true colour needs a colorimeter held against the panel, not a web page. What a browser can do is show you flat colours so your own eyes can compare, which is enough to find faults but not enough to calibrate anything.
They cannot tell you whether a fault is covered by a warranty. Every maker sets its own rules, and those rules differ by model and by country. The pages say what to look up rather than pretending to know the answer.
And they cannot see your screen. What you find here is what your own eyes find, with the background made as unhelpful to a fault as possible.
Getting in Touch
If a test does not work on your device, if something on a page is wrong, or if there is a test you expected to find and did not, it is worth telling us. Corrections are welcome and get acted on.