Dead pixel test

How to check for dead pixels

1. Press Start full-screen test. The screen fills with black; the controls and cursor hide after 2 seconds.
2. Look across the whole screen, edge to edge, for a dot that does not match the colour around it.
3. Tap, click or press → for the next colour, ← to go back. The order is black, white, red, green, blue and 50 % grey, then the dark grey and gradient screens. Esc or the Exit button leaves.
4. Each colour shows different faults, so go through all of them. You can also open one colour directly from the swatches.

On an iPhone, web pages can't take over the full screen. Turn the phone sideways, or tap aA in the address bar and choose Hide Toolbar, to see as much of the screen as possible.

Dead vs stuck vs hot pixels

Each pixel is made of red, green and blue subpixels. Which colour reveals a fault tells you what kind it is:

• Dead pixel: stays black on every colour, easiest to see on the white screen. All its subpixels are off. Dead pixels almost never come back.
• Stuck pixel: stays one colour (red, green, blue, or a mix like yellow or cyan), easiest to see on black or on a colour that should hide it. One or more subpixels are stuck on. These sometimes recover.
• Hot pixel: stays bright white on every colour, best seen on black.

A dot that moves when you wipe the screen is dust. A dot that is visible only on one colour and only up close is usually a single stuck subpixel.

Warranty: many monitor makers describe their pixel policy using the pixel fault classes of the ISO 9241-307 standard, and policies differ: some replace a screen for a single bright pixel, others only above a set number of faults or in the centre zone. Check your maker's own policy, and check new screens within the shop's return window, which is often easier than a warranty claim.

Backlight bleed, uniformity and banding

Open Dark grey 5 % (backlight bleed) in a dark room. On LCD screens, light leaking around the edges or in the corners is backlight bleed; patchy bright clouds across the panel are clouding. A little bleed is common on LCD panels, especially IPS; strong bleed visible in normal use is a reason to talk to the seller. OLED screens have no backlight, so they don't bleed, but this screen shows uneven dark areas on them too.

The Gradients (banding) screen shows smooth colour ramps. Visible steps or stripes are banding. Some banding comes from the panel or its settings (low colour depth, aggressive picture modes), some from the graphics driver or a reduced colour format in the display settings.

Stuck pixel helper (with photosensitivity warning)

The helper is a small square (56 × 56 pixels) that flashes red, green, blue and white very fast. Flashing a stuck subpixel on and off sometimes frees it. To keep it safe, the square never covers more than that small area, and it only flashes while you hold it.

1. Read the warning and tick I understand, show the flashing square.
2. Press and hold the square to make it flash. Drag it while holding to move it over the stuck pixel. Release to stop.
3. With a keyboard: focus the square, move it with the arrow keys, and hold Space to flash.
4. Keep it over the pixel for a few minutes, then check with the solid colours again. Hide square puts it away.

If your device asks for reduced motion, the flashing square is switched off and the page explains why. The helper can't fix a dead (black) pixel, and it doesn't always work on stuck ones either.

Refresh rate and display info

The Your display panel measures the Refresh rate from the browser's frame timing over 2 seconds and rounds it to the nearest common rate, for example ≈ 144 Hz with "measured 143.9 Hz · 6.95 ms per frame". Battery saving, a background tab or a busy computer can lower it, and some browsers limit animation to 60 frames per second, so a 120 Hz screen can read 60 Hz here. Press Measure again after changing settings. If a high refresh rate monitor shows 60 Hz, check the refresh rate in your system's display settings and use a cable and port that support it.

The panel also lists the Screen size in real pixels and the scaling factor (Pixel ratio), the Browser window size, Colour depth, and whether the browser reports HDR and Wide colour (P3).

Related tests: the webcam test checks your camera, the reaction time test includes your screen's delay, and the mouse test checks your clicks. Our guide to reading test results explains Hz and other numbers. Nothing on this page is recorded or uploaded. More tools: device tests.