Display Test Black level test
Black level test
Check whether your screen shows true black and how much shadow detail it keeps. You click the darkest of 16 near-black boxes you can still see – a quick check for OLED, LCD and phone screens.
About 1 minute · Free, no sign-up · Results stay on this device.
How the test works
A short "Get ready" list comes first. Dim the room – lamps and daylight hide the darkest shades. Keep your usual picture mode, so the result describes the screen as you use it. On iPhone, Safari can't go full screen, so the test suggests Share → Add to Home Screen. You can also say what kind of screen you have, so the advice fits.
Then you see 16 boxes on pure black. Computers usually store a shade as a number from 0 (black) to 255 (white), and each box is labelled with its number, from 0 up to 32 in small steps. Give your eyes a few seconds, then click the darkest box you can still see, or choose "I can't see any box". Box 0 is the same pure black as the background, so it never stands out – pick it only if black itself looks grey or glowing.
What your result means
- Box 0 – not true black. Black itself looks grey or glowing.
- Box 1 or 2 – excellent. The screen keeps shadow detail almost down to black.
- Box 3 to 5 – good. This is typical.
- Box 6 or higher – black crush. Shades below that merge into black, so dark scenes in films and games lose detail.
- No box visible. The room may be too bright, or the screen crushes shadows.
True black means the screen gives off no light at all. OLED pixels can switch off completely, so on an OLED in a dark room, black should look like the screen is off. LCD screens (IPS, VA) have a backlight behind the picture that always glows a little.
When black looks grey
On an OLED, black that looks grey usually means a signal range mismatch: the computer and the monitor disagree about which number is black. Set the graphics driver to Full RGB – in NVIDIA Control Panel, Change resolution → Use NVIDIA color settings → Output dynamic range: Full; in AMD Software, Pixel Format: RGB 4:4:4 Pixel Format PC Standard (Full RGB) – and set the monitor to match. Light falling on the screen also looks grey, so dim the room.
On an LCD, the backlight glows through black. Turn on local dimming if your monitor has it – it dims the backlight behind dark areas – and dim the room. Glow at the edges and corners is checked in the uniformity test.
When dark details disappear
- Make the graphics driver and the monitor use the same RGB range – both Full or both Limited.
- Set the monitor's gamma to 2.2 instead of 2.4. Gamma sets how fast shades rise out of black – 2.4 keeps the darkest ones darker.
- Turn off "dynamic contrast" in the monitor's menu.
- In Windows HDR mode, run the free Windows HDR Calibration app from the Microsoft Store.
Then run the test again. To check the smooth steps between shades, try the banding test.
Questions
What is a good black level test result?
Seeing box 1 or 2 is excellent, and 3 to 5 is typical. On a good screen in a dim room, black itself should look black, not grey.
Why does black look grey on my OLED?
OLED pixels switch off for black, so grey usually comes from a signal range mismatch between the graphics card and the monitor, or from room light reflecting off the screen. Set both to Full RGB and dim the room.
What is black crush?
Black crush means the darkest shades are shown as pure black, so you lose detail in night scenes and shadows. A range mismatch, gamma 2.4 or "dynamic contrast" can all cause it.
Does the black level test work on a phone?
Yes. The boxes are drawn in the browser, so the test works on iPhone and Android. Dim the room and keep your usual brightness. On iPhone, use Share → Add to Home Screen and open the test from there to run it in full screen.
Can a browser measure black level in nits?
No. Browsers can't read brightness from the screen, so this is a careful visual check of which shades your screen still tells apart from black. Measuring nits needs a meter such as a colorimeter.
Check everything in 5 minutes
The full Display Test covers HDR brightness, black level, gradients, colours, motion, dead pixels and burn-in – one simple step at a time, with a report you can save as PDF.
More single tests
- HDR brightnessHow bright highlights get, and how much big bright areas dim.
- GradientsStripes in smooth colour ramps – 8-bit or 10-bit.
- ColoursStandard sRGB, Display-P3 or beyond.
- Refresh rateYour Hz right away, plus motion clarity.
- Dead pixelsDark or stuck dots on full-screen colours.
- Burn-inFaint shapes left by static images on OLED.
- UniformityPatches, darker edges and backlight bleed.
Every pattern is drawn live at your display's native resolution with exact brightness values – no compressed video. · PeakNits home · Music visualizer · Privacy · Statistics settings