How the test works
The page fills your entire screen with a single white shade. Four levels are available: pure white, 75%, 50% and 25%. Full white is the first one to check; it is the page where a dead pixel shows as a black dot and where a speck of dust or a fingerprint stands out. The lower levels matter for uniformity: an unevenly lit panel hides its problems under full white and gives them away on a mid grey, where the eye is far more sensitive to small differences in brightness.
The level can be changed before you start or while the page is open, with the left and right arrow keys or a tap. A small timer sits in the corner and fades out after a moment without movement, so the screen shows nothing but the colour. Move the mouse or touch the screen to bring it back, and press Escape, swipe down or tap the cross to leave.
- Clean the screen before you judge anything. Fingerprints and dust look like pixel defects on white.
- Turn the system brightness up and switch off any night mode or colour filter.
- Look at the screen straight on. Viewing angle changes both brightness and tint on most LCDs.
Nothing is measured and nothing is sent. The page draws a colour; your browser does the rest.
What the result means
The result card shows how long the page stayed on and at which level. What you saw on the screen is the real result:
- A clean, even field. Nothing to do. Panels rarely get worse without a reason, so you do not need to repeat this often.
- A black or dark dot that stays in place. A dead pixel or a dead sub-pixel. Confirm it with the dead pixel test, which shows the primaries one by one.
- A smudge that moves when you clean. Dirt, not a defect. Most "dead pixels" reported on new devices are this.
- A visible tint towards yellow, pink or blue. Compare with white paper in daylight. A colour profile or the monitor's colour temperature setting usually fixes a mild cast.
- Darker corners or bands. Uniformity is limited on edge-lit panels. If it bothers you on real content, not only on a test page, it is a reason to return the device.
What to do about a problem
Tint can often be corrected. On a monitor, set the colour temperature to 6500 K or "sRGB" in the on-screen menu. On Windows, macOS and most phones, a colour calibration or "display profile" setting adjusts the white point. A colorimeter does it properly if you work with colour.
Dead pixels and uniformity problems cannot be corrected by software. There is no trick that revives a pixel that receives no power, and no setting that moves light to a dark corner. The only decisions are whether to accept it and whether the seller will exchange the unit.
When to return or claim the warranty
Run the white page on the first day you own a new screen, before the return window closes; most shops accept a return within fourteen days without a reason. For a warranty claim, photograph the defect at 50% white in a dim room, with the camera exposure locked, and note the position. Uniformity is usually not covered unless it is far outside the manufacturer's own tolerance, so a dead pixel claim is the stronger one: check the panel class in the specifications, since Class I panels are replaced for any defect and Class II panels only from a small number of dots.
Frequently asked questions
Does the white level change my screen's brightness?
No. The level changes the shade the page draws, from pure white down to a 25% grey. The actual backlight or OLED drive is controlled by your operating system, and a web page cannot touch it. For the brightest possible white, pick 100% here and set the system brightness to maximum.
Why does the white look yellow or blue?
Every panel has a colour temperature, and many devices shift it warmer in the evening (Night Light, Night Shift, True Tone). Turn those off, then hold a sheet of plain white paper next to the screen in daylight. A slight tint against paper is normal; a strong yellow or blue cast that a colour profile does not fix is a panel property you cannot change.
Is a white screen safe for an OLED?
For a few minutes, yes. OLED panels limit their own power on large bright areas (automatic brightness limiting), so a full white page will actually look dimmer than a small white window. Avoid leaving full white on an OLED for hours at maximum brightness; there is no reason to for a test.
Can I use this page as a light?
Yes. A laptop or monitor at 100% white and full brightness gives a soft, even light that is good for video calls, reading a document under the desk or finding something in the dark. It is not bright enough for photography, but for a face at arm's length it works well.
Why is the middle brighter than the corners?
A gentle fall-off towards the edges is normal on edge-lit LCDs, where the light enters from one side and is spread by a diffuser. It becomes a defect when it looks like distinct bands or blotches, or when one corner is clearly darker than the opposite one. Drop the level to 50% to see it more easily.