Red screen and full-screen color test
Full-screen red, black, white, green and blue, plus a ghosting test.
Click or press Space or the right arrow for the next screen, left arrow to go back, Esc to leave.
Related tools
Test for dead pixels
Cycle your screen through solid colors and line patterns to find dead, stuck, and hot pixels.
Test touch screen
Drag across a grid to find dead zones on a touch screen and check how many fingers register at once.
Test reaction time
Click when the screen turns green and get your reaction time in milliseconds, averaged over five rounds.
What you can check with a plain screen
Five solid colors
Red, black, white, green and blue, edge to edge.
Ghosting test
A block that crosses the screen at a fixed speed on a light and a dark band.
Real fullscreen
Uses the browser's fullscreen mode, and falls back to the full window where it is blocked.
Private, nothing uploaded
The test runs in your browser tab. No file, key press, click or sound leaves your device.
Run the screen test in three steps
- 1
Pick a color or the ghosting test
Choose red, black, white, green, blue or ghosting, or just press Start to begin with red.
- 2
Go full screen and look closely
Dim the room. Look for uneven patches, glowing edges or tinted corners, and for trails behind the moving block in the ghosting test.
- 3
Step through the other screens
Click or press Space or the arrow keys for the next screen. Escape leaves the test.
What a solid screen shows you
A single flat color is the fastest way to see what the panel is really doing.
Checking backlight bleed
Black screen in a dark room, from your normal seating distance.
Judging gaming monitors
Use the ghosting test to compare response settings such as overdrive.
Inspecting a screen before buying
Run white and black on a display model or a fresh unit.
Frequently asked questions
What does a black screen test show?
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On a black screen in a dark room, you can see backlight bleed (glowing edges or corners on an LCD), clouding, and bright stuck pixels. A good OLED panel shows true black with none of that.
What does a white screen test show?
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A white screen shows uneven brightness, color tint in one corner, yellow patches, dark dead pixels and dirt on the surface. Look at it from straight on and from a slight angle.
What is screen ghosting?
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Ghosting is a faint trail behind moving objects, caused by pixels that change color too slowly. The ghosting test moves a block across a light and a dark background at a fixed speed. A clean block is good, a smeared trail behind it is ghosting.
Is a red screen test the same as a dead pixel test?
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They overlap. The dead pixel test adds line patterns and more colors for hunting single bad pixels. This page is better for judging an overall color, uniformity and motion response.
Why do the colors look different from my other devices?
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Every panel has its own brightness, color temperature and calibration. A pure red on one screen can look more orange or deeper on another. Compare against a trusted screen if color accuracy matters.
Can I use the screen test on a TV?
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Yes. Open this page in the TV's browser, or cast your browser tab to the TV, and run the same test full screen.
Run the screen test now
Free, no account needed.