Free Online Dead Pixel Test - Instantly Check Your LCD & OLED Screen Quality

Press any color tile above to start a full-screen color cycle - sweep red, green, blue, black, white, and yellow to spot stuck pixels, dead pixels, or backlight bleed. No install.

Also called a screen test, display test, panel test, or monitor test - the same full-screen color cycle covers all four names and works on LCD, OLED, and LED panels.

Wondering if your screen has dead pixels or other display issues? Use the free online dead pixel checker to quickly identify faulty pixels on LCD, OLED, or LED screens. The full-screen color test paints a solid red, green, blue, black, white, or yellow field across the entire viewport so dead, stuck, or discolored pixels stand out against a uniform background, and the three live readout numbers below the tiles let you verify the actual painted resolution without downloads.

What the three resolution readouts mean. Under the color tiles the page lists three live numbers: your viewport, your screen resolution, and your native screen resolution (the resolution multiplied by window.devicePixelRatio). Confirm the native number matches your laptop or monitor spec sheet before flagging a suspect dot - on a hi-DPI panel a single CSS pixel hides several physical sub-pixels behind it, and a stuck sub-pixel can hide between them.

Which color reveals which defect. Pick one tile at a time so each defect class has a chance to surface against the field that exposes it. Black reveals stuck-bright pixels (a subpixel jammed on shows as a coloured dot against the dark field). White reveals dead-dark pixels and surface dust (a permanently off subpixel reads as a black speck, and a fleck of dust looks the same shape). Red, green, and blue reveal subpixel defects in the matching channel - a defect in one channel only is invisible on the other two. Yellow stresses both red and green subpixels at once, catching partial dimming the single-channel fields miss. Tick the "Test in full screen mode" checkbox before clicking the first color tile so the browser chrome retracts and defect areas near the panel edges are not covered.

Running a full pre-meeting hardware check? After the screen test, verify the rest of the input surface with the microphone test (level metering, permission check) and the camera test (resolution, preview). Together the three take under a minute and cover every hardware surface a typical video call depends on.

Going deeper on pixel defects? Read Dead pixel testing guide for the dead-vs-stuck-vs-hot taxonomy and the warranty-return threshold most manufacturers apply, and How to test for dead pixels before returning a monitor for the evidence pack (screenshots, pixel counts, test conditions) that speeds up an RMA.

Screen test passed today, but the laptop travels with you? Read Device test checklist for remote work for the schedule that catches new dead pixels, backlight bleed, or a loose display cable on a regular cadence rather than only at warranty-claim time. Pairs the screen check with mic, webcam, and keyboard tests in one 90-second sweep.

Spot key issues alongside the screen issues? Run a keyboard test to confirm every key registers - non-working keys are easier to surface in the same browser session as the screen check, and the keyboard test takes under thirty seconds.

Searched a different name for the same check? Read Screen / display test synonyms for what each name (screen test, display test, panel test, monitor test) actually covers, and What an LCD test does (and when to run one) for the underlying pixel check explained in plain terms - both pair with the colour cycle above so you know whether the right tool is open for the question you typed in.

Wondering whether to install a native app instead? Read Screen test online vs app - which is more accurate for the side-by-side: panel-level defects (dead pixels, uniformity, bleed) read the same in both; refresh-rate, 10-bit / HDR, and ICC color profile checks need a native app because the browser abstracts those signals away.

Need help picking the right screen-test tool? Read Test LCD: Pick the Right Screen-Test Tool - the disambiguation guide that maps each query phrasing to the right tool in one decision table.

Free, in your browser, with nothing uploaded. The LCD dead-pixel test is built around a single decision: render a perfectly uniform color across the entire viewport so the reader can spot defects by eye, without installing software or creating an account. No tile click leaves the browser, no still is captured, and the page does not record anything between presses. Closing the tab is the only cleanup the test needs.

Need the full device-check index? Go back to the Device Test Tools hub - the central page lists this LCD test, plus the camera test, keyboard test, and microphone test in the order that catches the most pre-meeting faults first. The hub is the place to land when the screen check passes but another layer (audio, lens, key registration) may still be at fault.

Read the guide: LCD Screen Test

On phones and tablets the browser chrome covers a strip near the panel edges that can hide a stuck pixel sitting there. Tick the "Test in full screen mode" checkbox before tapping the first color tile so the chrome retracts and the colour paints all the way to the border - the edge rows where backlight bleed and stuck pixels most often surface stay visible during the sweep.

One platform detail worth knowing before the first tap on a phone. Android Chrome and Firefox enter true fullscreen on the checkbox tap and paint the colour edge-to-edge immediately; iOS Safari behaves differently, and the practical fallback (scroll once to retract the address bar, or rotate to landscape) is detailed in the dedicated Mobile fullscreen fallback FAQ section below so the same workaround doesn't repeat twice.

Why the yellow tile is the partial-dimming catcher. Each single-channel tile (red, green, blue) only reveals defects in one subpixel channel at a time, so a red subpixel running at sixty percent of normal output reads as the right colour against a red field and stays invisible on green and blue. The yellow tile lights both red and green subpixels at full intensity simultaneously, so the same partially dimmed red subpixel reads as a green-tinted dot against the uniform yellow field. Run yellow last in the sweep once red, green, and blue have all come back clean - that's when partial-dimming defects most often surface.

On a laptop the same color cycle covers the screen side of the hardware check; the clamshell panel reads the same as a desktop monitor under it. Pair it with the camera tool above to cover the lens in the same browser session - both surfaces stay inside the tab.

A few minutes of practice with the black tile separates true backlight bleed from a normal viewing-angle gradient. Hold the laptop or monitor straight on rather than at the angle the desk encourages, drop the room lights, and watch the corners and the top edge: bleed reads as a soft warm-grey wash that fades inward from the bezel, while a viewing-angle gradient is uniform and inverts when you tilt the panel the other way. The white tile gives the second pass - if a corner reads colder or cooler than the centre under uniform white at the same brightness, the bleed is real and worth a warranty conversation; if the cast disappears when the panel is square to the eye, the original reading was the viewing angle.

Reviewed by FreetoolOnline editorial team