Monitor Gamma Test
Estimate your display's gamma with the classic gamma-matching chart. Each patch surrounds a solid gray square with fine black-and-white lines; the square that blends into its stripes when you sit back or squint reveals your monitor's gamma. The sRGB standard is about 2.2. A fine-tune slider, a banding check, and shadow and highlight tests are below.
Gamma-matching chart
Sit back about an arm’s length or squint slightly. The patch whose centre square blends into its stripes is closest to your gamma.
For accurate results keep browser zoom at 100% and view on the display you want to test.
Fine-tune your gamma
Adjust the slider until the centre square disappears into the striped surround, then read your gamma below.
Banding & grayscale
Look for visible steps or stripes in the smooth ramp — a clean panel shows a seamless transition.
Shadow & highlight detail
You should be able to tell each swatch from its background. If the dark ones merge into black your gamma is high or brightness low; if the bright ones merge into white, highlights are clipping.
What monitor gamma is
Gamma is the tone-response curve that maps a pixel's signal value to the light your screen actually emits. It is a power function: displayed luminance rises roughly as the input raised to the power of the gamma, so a mid-gray signal of 50% does not produce 50% of full brightness. Because human vision is more sensitive to changes in dark tones than in bright ones, this curve lets 8-bit values be spent efficiently, giving finer steps in the shadows where the eye needs them. Gamma sets how light or heavy the midtones look; it is separate from brightness (the overall level) and contrast (the range between black and white).
How to read the matching chart
Each patch is a field of alternating one-pixel black and white lines, which average to exactly half of full brightness in physical light. Inset in the middle is a solid gray square. For a given display gamma there is one 8-bit gray whose emitted light matches that of the striped surround, computed as 255 x 0.5^(1/gamma). We render a square for gamma 1.8, 2.0, 2.2, 2.4 and 2.6. Sit back about an arm's length or squint slightly so the lines blur together: the patch where the inner square disappears into its surround is closest to your display's gamma. The 2.2 patch is marked because it is the sRGB and Rec. 709 target most content is authored for. Keep browser zoom at 100%, or the one-pixel lines will not render correctly.
Why gamma matters, and the sRGB 2.2 standard
sRGB, the default color space for the web, photos, and most content, targets an effective gamma of about 2.2, and Rec. 709 for HD video is close to it. If your monitor's gamma is too low, midtones and shadows look washed out and flat; too high, and the image looks dark and crushed with lost shadow detail. Accurate gamma matters most for photo and video editing, where you are judging shadow and highlight detail, and for gaming, where enemies hiding in dark corners either show up or vanish depending on your curve. Older Macs historically used gamma 1.8, which is why legacy material can look pale on a modern 2.2 display; since OS X 10.6 macOS also targets 2.2.
Adjusting gamma on Windows and Mac
On Windows, open Settings and search for 'Calibrate display color' to run the built-in wizard, whose gamma step uses a matching pattern much like this one; graphics-driver control panels (NVIDIA, AMD, Intel) also expose a gamma slider. On macOS, go to System Settings > Displays > Color, open a color profile or the Display Calibrator Assistant (hold Option when clicking Calibrate for expert mode) to adjust the target gamma and white point. Use the step bar below to check for banding, where a smooth ramp breaks into visible bands, and the near-black and near-white patches to check for black crush or white clipping. A browser test like this is a quick visual check, not a substitute for a hardware colorimeter, which measures the curve directly and builds an ICC profile.