Dead Pixel Test
Fill your screen with pure black, white, red, green, blue and more to spot dead, stuck and hot pixels. Check a new or used monitor, laptop or phone before the return window closes. Free, runs in your browser.
Dead pixel checker
Wipe the screen, set brightness to maximum, then start the test. Look over the whole panel on each colour from about 30 cm away. Click, tap, swipe or press the arrow keys or Space to change colour. Doing that turns auto-cycle off. Esc or the X button exits.
Jump to a colour
Choosing a colour turns auto-cycle off so that colour stays up.
Always black. Shows as a dark dot on white and bright colours.
Always one colour (red, green or blue). Easiest to see on black.
Always white. Shows as a bright point on the black screen.
Keys: → ↓ Space Enter next, ← ↑ back, A toggles auto-cycle, Esc exits. The X button exits too, including on phones with no Esc key. On phones that block the Fullscreen API (iPhone Safari), the test fills the browser window instead; hide the toolbars by turning the phone sideways or scrolling first.
How to check a screen for dead pixels
Dead, stuck and hot pixels
Each pixel is made of red, green and blue subpixels. A dead pixel gets no power or has a broken transistor, so it stays black on every colour. A stuck pixel has one or two subpixels locked on, so it glows red, green, blue or a mix like yellow even on black. A hot pixel has all three locked on and stays white. Stuck pixels can sometimes be revived with the dead pixel fixer; truly dead ones almost never come back.
Test before the return window closes
Does your screen do what you paid for? Run this test the day a new or used monitor, laptop, TV or phone arrives, not three weeks later. Shops usually take returns within 14 to 30 days with no argument, while a warranty claim means meeting the maker's pixel policy. On a used device, ask the seller to open this page on the screen before you hand over money. While you are at it, check the edges on black with the screen bleeding test and look for ghost images with the burn-in test.
Dust or a pixel?
Wipe the screen with a dry microfibre cloth first. A speck of dust looks like a dead pixel on white but vanishes or turns faint on black, and it moves when you wipe. A real bad pixel sits in the same spot on every colour. Look at it from an angle or through a magnifier or your phone camera zoomed in: a pixel defect is a sharp square aligned with the grid, dust is soft and round.
Manufacturer pixel policies
Most makers do not promise a perfect panel. Policies are based on ISO 9241-307 (formerly ISO 13406-2), which sorts panels into pixel fault classes: Class 0 allows no faults, while Class I and Class II allow a set number of bright, dark and subpixel faults per million pixels. Many consumer brands only replace a screen once it has several bad pixels, or a bright pixel near the centre, and some offer a zero-bright-pixel guarantee on premium models. Read the policy for your exact model, and take a photo of the fault on a solid colour screen as evidence.
Related tools
- Dead Pixel Fixer: flash rapid colours over a stuck pixel to try to unstick it.
- Solid Color Screens: any full-screen colour, for photos and inspection.
- Screen Bleeding Test: find backlight bleed and IPS glow at the edges.
- Burn-In Test: spot image retention on OLED and plasma screens.
- Refresh Rate Test: check the monitor really runs at its advertised Hz.
- Touch Screen Test: find dead zones on a phone or tablet touch screen.
Frequently asked questions
What is the difference between a dead, stuck and hot pixel?
A dead pixel stays black on every colour because it gets no power or its transistor is broken. A stuck pixel has one or two subpixels locked on, so it stays red, green, blue or a mix such as yellow, even on black. A hot pixel has all three locked on and stays white, which shows as a bright dot on black.
How do I leave the full-screen test?
Press Esc, or press the X button at the bottom of the screen. Arrow keys, Space, a click or a swipe change colour and turn auto-cycle off. If the browser entered full screen, Esc leaves full screen and closes the test, so the page underneath is usable again.
Why does the test not cover the whole phone screen?
iPhone Safari and some other mobile browsers block the Fullscreen API on ordinary web pages. The test then fills the browser window instead. Turn the phone sideways, or scroll so the address bar tucks away, then start again. Phones often have no Esc key, so use the X button to leave.
Which colours should I look at?
Check pure black, white, red, green and blue with brightness at maximum. Black shows stuck and hot pixels. White shows dead pixels, dust and smudges. Red, green and blue show a subpixel that will not light. Cyan, magenta, yellow and 50% grey are a second pass. The name on the dark label is the colour you are on.
Can this page repair a bad pixel?
No. This test only shows solid colours so you can look. It does not run a repair pattern. A stuck pixel can sometimes be worked on with the separate dead pixel fixer. A pixel that stays black on every colour rarely recovers, and nothing here can promise that it will.
How do I tell dust from a dead pixel?
Wipe the screen with a dry microfibre cloth first. Dust looks dark on white but fades or moves on black, and it looks soft and round. A dead or stuck pixel stays in the same grid square on every colour and has sharp edges.
Does one bad pixel mean I can return the screen?
Not always. Many brands follow ISO 9241-307 and replace a panel only after several bad pixels, or a bright pixel near the centre. Read the policy for your model while the shop return window is still open, and photograph the fault on a solid colour.