Designed for a clear job
When this tool is useful
- Darken a second monitor while keeping it awake
- Check for backlight bleed in a dark room
- Find bright, stuck, or hot pixels
Three simple steps
How to use it
- 01Lower room lighting for display inspection
- 02Open the black canvas in fullscreen
- 03Look from the center and corners without touching the panel
Second monitor
How do I make a second monitor completely black?
Move this page to the display you want to darken and open the black screen in fullscreen. The monitor stays connected and awake, so windows keep their positions while the unused display stops lighting the room.
A black webpage does not switch off the backlight on most LCD monitors, so it may still produce a faint glow. OLED panels can look much darker because individual black pixels can turn off.
Panel inspection
How do I test backlight bleed with a black screen?
Darken the room, set the monitor to a normal everyday brightness, and view the fullscreen black screen from your usual seating position. Bright patches near the edges can indicate backlight bleed; a glow that changes as you move may be normal IPS glow.
Do not judge a panel from an overexposed phone photo. Check it with your eyes, then use the red, green, blue, and gray monitor patterns to separate bright pixels from dust or reflections.
Nothing leaves your screen.
FullscreenKit runs this tool in your browser. It does not upload your colors, messages, timer settings, or test activity.