Guide
How to Check a New Monitor Before the Return Window Closes
Dead pixels, backlight bleed and IPS glow are three different things with three different verdicts. Here is…
Black Screen
Fills your entire screen with solid black. Finding stuck pixels, backlight bleed and IPS glow, all of which only show against black.
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Press Fullscreen, then look closely at the whole panel.
In short
A full black screen is where the three faults people actually return monitors over become visible, and where the single most misunderstood distinction on any LCD lives. Stuck pixels show as bright coloured dots, because a pixel latched on in red, green or blue is invisible against white and obvious against black. Backlight bleed shows as light escaping around the edges of the panel — and crucially it stays in the same place whatever angle you look from. IPS glow is different: a silvery wash across a corner that MOVES or fades as you shift your head. Bleed is a manufacturing defect and grounds for a return; glow is how the panel technology works and is not. Confusing them is why people return good monitors and keep faulty ones. Judge it in a dimly lit room at your normal brightness, not in a pitch-black one at maximum, because every LCD ever made looks unacceptable under those conditions. On OLED, black is genuinely black, and any glow at all is worth investigating.
How to use the Black 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 Black Screen
The Black Screen fills your entire screen with solid black. Finding stuck pixels, backlight bleed and IPS glow, all of which only show against black. 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
- Finding stuck pixels, backlight bleed and IPS glow, all of which only show against black.
- 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.
Explained in our guides
All guidesFrequently 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.
Is there a limit on how often I can use the Black Screen?
Free, unlimited, and no email address required. You can use it a hundred times a day and nothing changes.
Does anything I enter leave my computer?
No. The Black Screen runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
What do people use the Black Screen for most?
The jobs it is built for: finding stuck pixels, backlight bleed and IPS glow, all of which only show against black. 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.
What do people usually get wrong here?
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 Black 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.
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