What this tool does
A screen test fills the whole display with a solid colour so your eyes can find the defects: red, green, blue, white and black in turn, then greyscale steps and a grid.
Solid fills are the only reliable way — dead pixels, stuck pixels, colour patches, backlight bleed and uneven brightness are all hidden by ordinary content, and only a single flat colour exposes them.
Nothing is installed and nothing is calibrated or changed. The tool only paints test patterns over the screen; the judgement is yours.
How to use
- Set browser zoom to 100% Zoom merges several physical pixels into one, which can hide a single dead pixel. Also turn off night light, dark mode and dynamic HDR — they shift colours.
- Press start The page goes fullscreen and cycles through 11 steps. Space or a click advances, arrow keys move back and forth, Esc exits.
- Check each step Each step shows a hint telling you what to look for. Pay special attention to the edges and corners — backlight bleed almost always starts there.
FAQ
Can this damage my screen?
No. It only displays flat colours; nothing is written and no brightness or colour settings are changed. A long white screen draws a little more power, so just exit when done.
Is one dead pixel a defect?
It depends on the manufacturer policy and panel grade. Most consumer displays tolerate a few dead pixels, but defects in the centre area are usually grounds for a replacement. This tool finds them; it does not judge whether they are within spec.
Why do I see nothing?
Most likely the browser blocked fullscreen — check for a blocked-fullscreen notice near the address bar. You can also download the SVG and open it fullscreen in any viewer.
Does it work on phones?
Yes. Mobile browsers support fullscreen too; tap to advance. OLED phone screens are more prone to isolated bright pixels, so look carefully on the black step.
Why download the SVG?
SVG is vector, so it stays sharp at any resolution and is never resampled into fake defects. Useful for casting to a TV, sending to someone else, or keeping a record.
Is any data uploaded?
No. The page makes no network requests; the test image is generated locally.
Limits
Visual checks only — not a substitute for a colorimeter or factory test equipment.
Screen content is never read or uploaded (browsers do not allow it); resolution figures come from the browser and may be wrong when zoomed.
No repair advice and no judgement about warranty policy.