Gamma Test: Find Your Monitor’s Real Gamma and Banding Online
Gamma decides how bright midtones look: the same 50% signal can render as pale or dark depending on whether your panel tracks 1.8 or 2.4. This free gamma test puts a 1-pixel black/white dither next to solid gray for five gamma values — the strip that melts into its neighbor tells you exactly what your display is doing. Smooth gradients on the same page expose banding.
How to read the gamma chart
Press F for fullscreen and step back about a meter. Each row of the gamma chart splits in half: one side is a 1px checkerboard of pure black and pure white (which averages to exactly 50% gray), the other side is a solid gray computed for a gamma of 1.8, 2.0, 2.2, 2.4 or 2.6. Squint until the dither dissolves into a flat tone, then find the row where the two halves match. That label is your display’s effective gamma.
A reading between 2.1 and 2.3 is on target for sRGB and web content. Below 2.0 the image looks washed out with milky shadows; above 2.4 everything gets heavy and detail drowns in dark scenes. Note that many monitors ship at roughly 2.4 in their "Vivid" modes — if movies look soupy, check here first. Displays also hide luminance flicker at low brightness; a wavering dither half can hint at PWM dimming (see the refresh rate page for flicker checks).
Hunting banding in the gradients
Switch to the gray banding pattern: two mirrored black-to-white gradients. Sweep your eyes across them — a clean panel transitions smoothly; visible stripes, steps or contour rings mean the processing chain is starving the panel of gray levels. The RGB version does the same for each primary, where faint rings around dark reds or blues are common on 8-bit panels feeding 10-bit content.
Banding has three usual suspects: limited RGB range (16-255) on the GPU output, aggressive "dynamic contrast" or picture enhancers in the OSD, and low-bit video players. Fix them in that order. If stripes persist after setting full range and disabling enhancements, compare against the grayscale test — merged steps there confirm a bit-depth limitation of the panel itself rather than a settings issue.
Correcting a wrong gamma
Start in the monitor OSD: Standard or sRGB modes typically track nearest to 2.2, while Cinema/Movie modes often target 2.4. If the OSD has no gamma control, use your GPU control panel — NVIDIA, AMD and Intel all expose a gamma slider; nudge it and re-run this chart until the 2.2 row matches. macOS users can refine further in System Settings with a calibrated profile.
For exact work — photo editing, print proofing — a hardware calibrator beats any eye test, and the color calibration page gives you the before/after patterns to verify its profile. For everything else, matching the 2.2 row on this chart plus clean gradients on the banding patterns is the practical standard. Finish with the HDR test if your display claims HDR: tone mapping problems often masquerade as gamma errors.
Frequently Asked Questions
What is a gamma test?+
It compares a solid gray patch against a 50% black/white dither at several gamma values. The row where both halves look identical reveals the gamma your display actually renders, which can differ from its advertised spec.
What gamma should my monitor be?+
2.2 is the standard for sRGB, the web and most Windows/macOS content. Cinema modes sometimes target 2.4 for dark rooms. Readings between 2.1 and 2.3 are fine for general use.
Why does the dither half look noisy or shimmery?+
The 1px checkerboard is intentionally fine. View it from about a meter away or squint so it blends into flat gray. If it visibly flickers, your display may use PWM dimming — check the refresh rate page.
What is banding and how do I fix it?+
Banding is visible stripes in what should be a smooth gradient. Set your GPU output to full RGB range, disable dynamic contrast and picture enhancers, and use a higher-bit video player. Persistent banding across all sources suggests a panel bit-depth limit.
Does gamma affect color accuracy too?+
Yes. Wrong gamma shifts every in-between tone — skin looks sunburned or gray, saturation swings with brightness. Correct gamma is a prerequisite before judging color with the color checker patterns.
Can I trust this without a calibrator?+
For judging relative changes and gross errors, yes — the dither method is the classic broadcast reference. For absolute accuracy in print or pro photo work, pair this page with a hardware calibrator.