Red Screen
Fill your whole display with red in one click. Nothing to install, nothing uploaded.
Red wallpaper
What a red screen is for
Showing one primary color at a time is how you isolate a faulty subpixel: a dead red subpixel is invisible on a normal image but obvious on a full red field. Red light also preserves dark adaptation, which is why astronomers and darkrooms use it.
Why red preserves night vision
The eye has two kinds of photoreceptor. Cones handle colour and detail in good light; rods handle low light, and it takes around twenty to thirty minutes in darkness for them to reach full sensitivity. Rods are far less responsive to long wavelengths than short ones, so deep red light lets you read an instrument or a chart while leaving dark adaptation largely intact, where a moment of white light destroys it. That is why observatories, darkrooms, submarine control rooms and aircraft cockpits have used red lighting for decades, and why a red screen at low brightness is the sensible one to have open in the dark.
Finding a failed red subpixel
Every pixel on the display is built from a red, a green and a blue subpixel, and a full red screen drives only the red ones. A red subpixel that has died shows as a dark dot against this field and is effectively invisible on any other colour, because the other two channels mask it. That is the whole reason a proper dead pixel test steps through the primaries individually rather than stopping at black and white. Run this one at full brightness and look across the entire panel, corners included, before deciding a screen is clean.
Red as a warning colour, and its limits
Red is the near-universal colour for stop, danger and error, which is partly convention and partly that it holds attention well against most backgrounds. It carries two real weaknesses worth knowing. Red on black is a poor pairing for text despite looking dramatic, because the two are closer in perceived lightness than they appear and fine detail smears. And red-green colour blindness affects roughly one in twelve men, so anything that signals purely by turning red is invisible to a substantial share of any audience. Signalling needs a second cue: a shape, a word, a position.
Click the panel above to go fullscreen and press Esc to come back. The color is drawn by your browser, so nothing is installed and nothing is uploaded.
Red color values
The exact values for this shade, if you need to match it somewhere else.
| Hex | #FF0000 |
|---|---|
| RGB | 255, 0, 0 |
| HSL | 0°, 100%, 50% |
| CMYK | 0%, 100%, 100%, 0% |
| Contrast on white | 4:1 |
| Contrast on black | 5.25:1 |
Contrast ratios follow the WCAG formula. Anything at or above 4.5:1 is readable as body text against that background, and 3:1 is the floor for large headings. Red reaches that bar on black.
Colors close to red
Measured as perceived difference, not by name, so these are the shades that genuinely sit nearest red to the eye.
Questions
Does this work on a phone?
Yes. On mobile the page fills the screen when you tap the panel. Some browsers keep a thin status bar visible, which is a browser limit rather than something the page controls.
Will a red screen fix a stuck pixel?
Sometimes. A stuck pixel is lit in one color and can occasionally be freed by cycling colors rapidly for a few minutes. A dead pixel receives no power at all and cannot be recovered in software.
What is the hex code for this red screen?
This page uses #FF0000. The same value is shown in RGB, HSL and CMYK further down, so you can match this exact shade somewhere else.
Does a red screen save battery?
Not meaningfully. Only black saves power, and only on OLED and AMOLED panels where an unlit pixel is genuinely off. Any lit color, including a dark one, draws power.
Can I download this red as a wallpaper?
Yes. There is a ready-made 1920 by 1080 PNG on this page, and the panel above will generate the same color at your own screen size, at 1440p or 4K, or at phone dimensions. No watermark and no sign-up.
Is it free?
Yes, and there is no sign-up. The page draws a color; that is the whole tool.