Red screen
Click the panel to fill your screen with red. Turn brightness down for a dim light that’s easy on dark-adapted eyes.
What people use it for
Keep your night vision
Dim red light disturbs dark-adapted eyes the least — stargazers use it to read charts. Keep brightness low.
Mood light
A red glow behind a monitor or TV for movies, games or a party.
Check red subpixels
A dot that stays dark on red is a dead red subpixel; on black it shouldn’t light up at all.
Photo accent light
Hold a phone or tablet off to the side for a colored rim light on a subject.
Keyboard shortcuts
- F
- Full screen
- Esc
- Exit full screen
- ← →
- Previous / next color
- ↑ ↓
- Brighter / dimmer
Every color
More screen tools
Dead pixel test
Five colors, one at a time, to find dead and stuck pixels.
Refresh rate test
See your screen’s real Hz and spot stutter.
Screen test
Gradients, black level, uniformity, gamma and sharpness.
Test pattern
Color bars and a test card at your native resolution.
Zoom light
A soft, warm light for video calls from a spare screen.
Background images
Plain color PNGs for desktops, phones and 4K.
Questions
Which red is it?
Pure red, #FF0000: red subpixels fully on, green and blue off. Dark red and crimson are softer.
How do I make it dimmer?
Lower Brightness, or press ↓ in full screen. Turning your display’s own brightness down dims it further.