01
White Screen
Fills your entire screen with solid white. Cleaning the screen, spotting dust and dark…
Red Screen
Fills your entire screen with solid red. Checking the red sub-pixels across the panel and revealing pixels stuck off in red.
Screen Tests
Nothing uploaded
No sign-up
Free, unlimited
Press Fullscreen, then look closely at the whole panel.
In short
A full red screen drives only the red sub-pixel of every pixel on the panel, which isolates one third of the display and makes two things visible that a mixed image hides. A pixel whose red sub-pixel is dead shows as a black dot in the red field while looking perfectly normal in ordinary use, because the other two channels cover for it. And a pixel stuck ON in red disappears here — it matches its background — which is exactly why a proper pixel check cycles through several colours rather than trusting one. Red is also the channel where compression artefacts and colour blotching tend to show up first on cheaper panels, because red is the channel most heavily compressed in video encoding. What red will not tell you much about is uniformity: the eye is relatively poor at judging brightness variation in a saturated red field, and grey is the right tool for that. Fullscreen, native resolution, dark room, and wipe the screen first so dust is not mistaken for a fault.
How to use the Red Screen
- The test starts on its own — no button to press and nothing to install.
- Follow the prompt in the test panel and watch the readings update live.
- Press Reset to start over with a clean slate.
About the Red Screen
The Red Screen fills your entire screen with solid red. Checking the red sub-pixels across the panel and revealing pixels stuck off in red. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.
What people use it for
- Checking the red sub-pixels across the panel and revealing pixels stuck off in red.
- Checking a monitor or phone screen before a return window closes.
- Using as a plain backdrop for photography or for cleaning the screen.
Press Fullscreen above before judging anything. A colour patch surrounded by page furniture tells you very little — the panel needs to be filling the whole screen, ideally in a dark room, with any night-light or blue-light filter switched off.
Frequently asked questions
What is the difference between a dead and a stuck pixel?
A dead pixel receives no power and stays black on every colour. A stuck pixel is latched on and shows the same bright red, green or blue dot against every background. Stuck pixels sometimes recover; dead ones never do.
How do I tell a dead pixel from dust?
Dust sits on the outside of the glass and moves or disappears when you wipe the screen with a microfibre cloth. A dead pixel does not move and stays in exactly the same position on every colour.
How many dead pixels before I can return a monitor?
That depends on the manufacturer's policy, which is usually written against the ISO 9241-307 pixel fault classes. Most consumer panels are sold to a standard that tolerates several sub-pixel faults, so check the specific warranty terms — and photograph what you find while the panel is still within the return window.
Does the Red Screen cost anything?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the utility.
Is the Red Screen safe to use with private information?
No. The Red Screen runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
What do people use the Red Screen for most?
In practice it gets used for three things: checking the red sub-pixels across the panel and revealing pixels stuck off in red. Checking a monitor or phone screen before a return window closes. Using as a plain backdrop for photography or for cleaning the screen. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is there a catch?
Press Fullscreen above before judging anything. A colour patch surrounded by page furniture tells you very little — the panel needs to be filling the whole screen, ideally in a dark room, with any night-light or blue-light filter switched off.
Why does the test start on its own?
No installation, no extension and no driver. The Red Screen uses the browser's own device APIs and begins as soon as the page loads, so there is nothing to press first. Press Reset at any point to start over with a clean slate.
Related screen tests tools
All 3802
Black Screen
Fills your entire screen with solid black. Finding stuck pixels, backlight bleed and IPS glow…
03
Green Screen
Fills your entire screen with solid green. Checking green sub-pixels — the channel the eye is…
04
Blue Screen
Fills your entire screen with solid blue. Checking blue sub-pixels and spotting the colour…
05
Cyan Screen
Fills your entire screen with solid cyan. Testing green and blue together, which often exposes…
06
Magenta Screen
Fills your entire screen with solid magenta. Testing red and blue together and checking for…
07
Yellow Screen
Fills your entire screen with solid yellow. Testing red and green together — the brightest…
08
Grey Screen
Fills your entire screen with solid grey. The best single colour for judging panel uniformity…
09
Orange Screen
Fills your entire screen with solid orange. A warm mid-tone that shows tint shifts across the…
10
Purple Screen
Fills your entire screen with solid purple. A dark saturated field, useful for checking colour…