Free Red Screen Test
A free red screen test: pure red fullscreen to check red subpixels.
Your Screen Info
Detected in your browser
Colour screens
Tap a colour to test it fullscreen
Custom colour
Custom colour
Shortcuts
- F Fullscreen
- → Next screen
- ← Previous
- Esc Exit
On a phone or tablet, tap to go to the next screen.
What is a red screen test?
A red screen test shows pure red (#FF0000), so only the red subpixel in each pixel is on. It isolates the red channel, which makes faults in that channel easy to see.
This test helps you find stuck green or blue subpixels, dead red subpixels and uneven red tone across the screen. It is a useful extra step after the white and black screen tests.
How to run the test
1
Set full brightness
Turn brightness up so small faults are easier to see.
2
Start the red screen
Click the Start button or press F to go fullscreen.
3
Scan for odd dots
Look for any dot that is not red, then press Esc or tap × to exit.
How to read your results
Black dot
The red subpixel at that spot is dead.
Green, blue or white dot
A green or blue subpixel is stuck on.
Darker or orange areas
Uneven red tone points to backlight or panel uniformity issues.
Related tests
Blue Screen Test
Check blue subpixels and uniformity
Dead Pixel Test
9 colours to find dead and stuck pixels
Color Banding Test
Smooth gradients that show stripes
Greyscale Test
Grey ramps and steps for tint and lost shades
Monitor Screen Test
Check a new or used monitor
Mobile Screen Test
Check a phone or tablet screen
Frequently asked questions
Why test the red channel on its own?
A single colour shows faults that a mixed image hides, because only one subpixel per pixel is lit.
Should I also test green and blue?
Yes. Use the colour screens next to the test to switch to green and blue, or run the full dead pixel test.
Is this test free?
Yes. It runs in your browser and nothing is uploaded.