Skip to content

Device test

Black — shows stuck pixels and backlight bleed

In fullscreen, tap or press a key for the next colour. Press and hold on a bad pixel to mark it (or right-click, or press M). Escape leaves.

Nothing uploaded

TV screen test: dead pixels and panel uniformity

Casting compresses the picture, and compression hides the single-pixel faults you are testing for. Use the TV's own browser or a USB stick instead.

FreeNothing uploaded

The short answer

To test a TV for dead pixels, display solid red, green, blue, white and black fullscreen and inspect from about 50cm — far closer than you would watch from. Avoid casting the tab: video compression smooths single-pixel faults and can hide one entirely. Use the TV's built-in browser, a directly connected computer, or image files from a USB stick.

Reading what you see

Dead, hot or stuck: what each one means

What the fault looks like, whether it can recover, and how it counts towards a return.

FaultWhat you seeDoes it recover?For a return
Dead pixelA black dot on every colour, clearest on whiteNoCounts as an always-dark fault. Class II panels may have 2 per million pixels
Hot pixelA white dot on every colour, clearest on blackRarelyCounts as an always-lit fault. Class II allows 2 per million, and some makers replace a panel for one
Stuck pixelA red, green or blue dot that vanishes on a field of its own colourSometimes, with rapid colour flashingA sub-pixel fault. Class II allows 5 per million pixels
Backlight bleedLight leaking in from an edge or corner on black, in a dark room. It stays put when you move your headNoNot a pixel fault, so there is no count. It is judged by eye: photograph it in a dark room
Dust or a markA soft-edged speck that seems to shift against the picture as you move your headWipe it offNot a fault. Clean the screen before you mark anything

The class figures come from ISO 13406-2, since carried into ISO 9241-307. Most consumer screens are sold as Class II, which works out at 4 always-lit, 4 always-dark and 10 sub-pixel faults at 1920 × 1080 (Full HD), 7 always-lit, 7 always-dark and 18 sub-pixel faults at 2560 × 1440 (QHD) and 16 always-lit, 16 always-dark and 41 sub-pixel faults at 3840 × 2160 (4K). A maker's own warranty can be stricter or looser, so read it for your model.

Getting it right

Four things worth knowing

  • Connect directly or use a USB stick

    HDMI from a laptop, or solid-colour image files on a USB drive, both give an uncompressed field. Casting and screen mirroring do not.

  • Inspect close, then judge from your sofa

    Stand close enough to resolve individual pixels while inspecting. Then step back to your normal seating distance and decide whether the fault is visible in use — on a large panel, many are not.

  • Turn off every picture enhancement

    Noise reduction, motion smoothing and local dimming all alter a solid field. Switch to a plain picture mode — often called Filmmaker, Cinema or PC — before judging uniformity.

  • Dirty screen effect shows on grey, not black

    Faint vertical bands across a solid mid-grey field are a uniformity problem, most visible on sport and panning shots. A black field will not reveal it at all.

Nothing leaves your device

This test runs entirely in your browser. There is no upload, no recording and no server that could receive anything — close the tab and it is gone.

  • No sign-up and no account
  • Nothing recorded or stored
  • Works with an ad blocker on
  • Free, and staying free
FAQ

Questions people ask

Anything we've missed?

Tell us

Can I test a TV by casting this page?

You can, but the result is unreliable. Cast and mirror paths compress video, and compression removes single-pixel detail. Use the TV's own browser or a directly connected source.

How close should I look?

Close enough to resolve individual pixels, which on a large 4K panel means roughly 30 to 50cm. Then judge from your real seating distance whether it actually matters.

What is the dirty screen effect?

Uneven brightness across the panel, showing as faint bands or blotches on uniform content. It is most obvious on sport and on grey fields. It is a uniformity fault rather than a pixel fault.

Is there a burn-in risk from this test?

Not from a few minutes. OLED burn-in comes from static content over many hours. Do not leave a solid colour on an OLED TV and walk away.

Test it for something specific

Other device tests

Someone on a video call at a desk, holding a mug
Sent anywhereNothing
Photo by Helena Lopes on Unsplash
Before it matters

Find the problem now, not mid-sentence

Every one of these runs in the browser and checks one thing properly. Nothing is uploaded, nothing is recorded, and none of them need an account.

Related reading

Guides worth reading