Contrast Test
A grid of nearly identical black squares from 0% to 7% gray on a black background, plus white-level squares from 93% to 100%. Adjust your monitor's hardware brightness and contrast until you can just barely see the 1% square — the standard manual calibration step for black level and contrast.
What you can use it for
- Calibrate monitor contrast with hardware buttons
- Find crushed blacks and clipped whites
- Set up a display for photo or video editing
- Match black levels across dual monitors
How it works
- 1. Customize. Open the Customize panel to set text, colors, theme, and animation speed to your liking.
- 2. Go fullscreen. Click Fullscreen for an immersive, distraction-free display on any screen.
- 3. Done. No login, no install, nothing to download — it runs instantly in your browser and your settings are remembered.
Frequently asked questions
How do I use the black level test?+
In a dim room, lower contrast until the 0% square matches the background, then raise it until you can just barely see the 1% square. Squares above that should become distinguishable.
What is white clipping?+
When brightness is too high, near-white shades merge into pure white and you lose highlight detail. The white-level grid helps you find that point.
More screen tests
Dead Pixel Test
Cycle full-screen colors to find dead and stuck pixels fast.
Screen Uniformity Test
Check brightness and color evenness across the whole panel.
Ghosting Test
A fast-moving object to spot motion blur and ghosting trails.
Backlight Bleed Test
Pure black screen with corner markers to spot edge light leak.
Color Banding Test
Smooth gradients to reveal color banding and bit-depth limits.
Resolution Test
Live readout of resolution, viewport, DPI scaling, and aspect ratio.
Text Sharpness Test
Tiny text samples to judge subpixel rendering and clarity.
Overscan Test
A 1-pixel grid and corner circles to fix overscan and cropping.