How to use
- Pick a colour, or drag the colour temperature slider for a warmer or cooler white.
- Lower the brightness if needed; the preview updates as you go.
- Click Show full screen to fill the screen with that colour.
- Click anywhere or press Esc to exit. In full screen, ↑ and ↓ change the brightness.
Options explained
- Colour temperature
- 2000 K is orange like candlelight, about 6500 K is standard white, and higher values look blue. For portraits a warm white around 4000–5500 K looks most natural.
- Brightness
- A web page cannot control the backlight, so this darkens the colour. For a stronger light, turn the system brightness all the way up.
- Keep the screen on
- Requests a screen wake lock in full screen so the display does not dim or lock while you use it as a light. Hidden when the browser does not support it.
Colour temperature values
The Colour temperature slider runs from 2000 K to 10000 K in steps of 100 K. The preset buttons use these values, and the slider moves with them:
| Setting | Kelvin | Colour |
|---|---|---|
| Warm white | 3000 K | #ffb16e |
| White | 6600 K | #ffffff |
| Cool white | 9000 K | #d2dfff |
Other points on the slider give #ff890e at 2000 K, #ffcea6 at 4000 K, #ffe4ce at 5000 K and #cadaff at 10000 K. The numbers are a curve fit to blackbody colours, so screens may render them a little differently.
Brightness (10% to 100%) multiplies each colour channel. White at 50% is #808080, and warm 4000 K light at 50% is #806753. In full screen, the arrow keys change brightness in steps of 10%.
Frequently asked questions
How do I make the light brighter?
Turn your system screen brightness to maximum and choose white at 100%. Laptops usually get brighter when plugged in.
Does it work on a phone?
Yes. Android phones go full screen. iPhone browsers do not allow pages to go full screen, so the colour fills the visible area; landscape gives you more of it.
How is this different from the dead pixel test?
The dead pixel test steps through fixed solid colours to find dead pixels, stuck pixels and backlight bleed. The white screen is for lighting and cleaning, and lets you set the colour, temperature and brightness.
Can leaving it on damage the screen?
OLED screens can get image retention from a static image shown for a long time, so exit when you are done. Ordinary LCD screens are not affected.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.