Check the connection and selected device, then repeat the failed check: fullscreen is refused.
Screen test
Open fullscreen solid and grid patterns, move between them with keys and mark visible defect coordinates.
Also known as: screen test, monitor test, display test, dead pixel test, stuck pixel test. Free, online, and no download required.
No permission neededNothing uploaded
Review the room and brightness prompt, then enter fullscreen.
01
What the screen test checks
| Check | How it is measured | Fails when |
|---|---|---|
| Pattern coverage | Nine solid and structured patterns are available in fullscreen. | Fullscreen is refused and the embedded pattern cannot fill the viewport. |
| Defect marks | Pointer positions are normalized to the active pattern bounds. | A mark cannot be restored or cleared. |
| Navigation | Arrow keys change patterns and F toggles fullscreen. | The active browser reserves a required key. |
If something failed
Check the connection and selected device, then repeat the failed check: a mark is misplaced.
Check the connection and selected device, then repeat the failed check: a pattern does not change.
02
How to read the result
How the screen test works
The fullscreen control is called only from a click. Once active, left and right arrows cycle the registered patterns, F toggles the fullscreen element and Escape uses the browser exit path. Pointer coordinates are stored as normalized fractions so marks remain aligned after a size change. The same bounded local-storage key is shared by the screen family.
What the result can establish
Dim the room and set the display brightness high before entering fullscreen. Move through every pattern slowly, mark only repeatable points and confirm them again on a second colour.
Measurement limits
The patterns expose areas for direct inspection but the browser cannot classify a physical panel defect. Scaling, browser zoom, colour management and ambient light can change the displayed result.
03
Screen test questions
How does a dead pixel test find a fault on my monitor?
Fullscreen solid colours remove every other element from the panel, so a pixel that does not match its field becomes obvious. Sweep red, green, blue, white and black, and mark any point that stays wrong on more than one colour.
What is the difference between a dead and a stuck pixel test?
Both use the same colour sweep, but the answer differs: a dead pixel stays black on every field, while a stuck pixel stays locked on one bright colour. That distinction decides whether a pixel refresher is worth trying or a warranty claim is the right next step.
Does this monitor test work on a laptop screen or a phone?
Yes. Any display the browser can fill works, including laptop panels, external monitors, tablets and phones. Browser zoom, colour management and operating-system scaling can alter fine grid patterns, so keep zoom at 100% for the structured fields.