Red Screen — Fullscreen Red Light for Night Use & Pixel Testing

A pure red fullscreen screen. Dim red light is easy on your night vision, and it’s a quick way to check your display for dead pixels. Free, runs locally.

What it does

This page opens a pure red (#ff0000) screen at the click of a button. Red is a popular choice for a low-glare night light, since dim red light is commonly used to protect night vision, for example while stargazing. It’s also one of the standard test colors for finding dead or stuck pixels.

How it works

A red screen drives only the red element of each pixel. For a night light, combine it with the Dimmer and lower your device’s brightness: the dimmer overlays black on top of the red, so you can go as low as you like. For a darker red, pick it from the named list (darkred, maroon) or drag up and down on the screen to change brightness.

How to use it

1. Press Go fullscreen.
2. Lower the brightness with the dimmer until it’s comfortable in the dark.
3. Tick Keep the screen awake if you need it on for a while. The Stay Awake tool is there if you only want to prevent sleep.
4. Press Esc to exit.

FAQ

Is red light better at night?

Dim red light disturbs your eyes’ dark adaptation less than white or blue light, which is why it’s common for astronomy and for navigating at night. It isn’t a medical device or a sleep treatment.

How do I check for dead pixels with red?

Look for dark specks or dots that stay a different color on the red screen. Then check the other colors in the Display test mode in the Color Screen tool.

Can I make a darker, redder red?

Yes. Choose darkred or maroon, type a hex such as #660000, or use the dimmer.

Privacy

Everything runs in your browser. Nothing is uploaded and no network requests are made while you use it.