How to use the white screen test
- Set your screen brightness to maximum and lower the room lighting.
- Tap Go full white screen. Your whole display turns solid white.
- Look carefully across the panel, corner to corner, for any spot that isn't pure white. A small dark or colored dot is usually a dead or stuck pixel; a hazy patch near the edges is usually backlight bleed.
- Wipe the screen first if you see faint smudges. Most marks turn out to be dust or fingerprints, not a hardware fault.
- Tap anywhere or press Esc to exit.
What a white screen test can tell you
- Dead pixels: a pixel that never lights up shows as a tiny black dot against the white.
- Stuck pixels: a pixel locked on one color (often red, green, or blue) shows as a colored dot.
- Backlight bleed: light leaking around the edges of an LCD panel, most visible as a bright patch in a dim room.
- Dust and smudges: dirt on the panel or under the glass, which a quick clean will usually fix.
- Panel uniformity: slight tints or unevenness across the surface of the screen.
Who this is for
- Buying a used monitor or laptopRun it on the spot before handing over money. A full white fill is the fastest way to catch a hidden panel fault.
- Just unboxed a new displayCheck it while you're still inside the return window, before a fault becomes your problem to live with.
- Filing a warranty claimConfirm and document a dead or stuck pixel with a clean, uniform background before you contact support.
- IT and repair techniciansA fast first pass to rule in or out a panel-level cause when a user reports a screen issue.
- Photographers and video editorsCheck your monitor for dust, smudges, or bleed before color-critical work.
- Anyone about to sell a deviceProve the screen is clean and fault-free in your listing photos.
Frequently asked questions
Why does a white screen reveal dead pixels better than my normal desktop?
White drives the red, green, and blue subpixels to full brightness at once, so a subpixel that's stuck off or locked on a single color stands out immediately. A busy desktop background hides exactly that kind of flaw.
I found a spot on my screen. How do I tell a dead pixel from a stuck pixel?
A dead pixel stays black no matter what color fills the screen. A stuck pixel shows a fixed color, often red, green, or blue, that doesn't change even though everything around it does. Running the white, black, red, green, and blue tests back to back is the fastest way to tell them apart.
Is a stuck pixel something I can fix myself?
Sometimes. Stuck pixels occasionally recover with gentle, repeated pressure near the spot, or by cycling bright colors over it for a few minutes. A genuinely dead pixel, where the subpixel has failed completely, usually can't be revived that way.
My screen looks slightly yellow or warm during the test instead of pure white. Is something wrong?
Probably not with the test. Most displays apply a blue-light filter, color profile, or auto-brightness adjustment by default. Turn those off temporarily if you want to judge true white, since they can make a perfectly healthy screen look tinted.
Does this work the same way on OLED screens as it does on LCD?
The white screen itself works identically. What you're looking for differs slightly: OLED panels don't have a backlight to bleed, so instead watch for uneven brightness across the panel or a faint color cast in one area.
Can I use this to check a used monitor or laptop before buying it?
Yes, that's one of the most common reasons people run it. Pull the test up on your phone, ask the seller to display it, and check the panel corner to corner before handing over any money.
Will leaving the screen at full brightness for the test damage it?
No. Displaying any solid color, including white, at full brightness is well within normal operating conditions for a screen. It's no different from displaying a bright web page.
The screen flickers slightly during the test. Is that a problem?
Usually not with the test itself. Faint flicker is often how a screen's automatic brightness or PWM dimming behaves at certain brightness levels, and it will show up on any full-brightness solid color, not just this one. If it's persistent across multiple apps and colors, that's worth mentioning if you do get the screen serviced.