Monitor Brightness Test
Set your monitor’s brightness control by eye and check that dark detail survives without being crushed or washed out. The full-screen test cycles through a shadow-detail pattern, a smooth black-to-white gradient, a stepped grayscale bar and solid white and gray fields — all drawn pixel-accurately on your display. A browser cannot read nits, so treat this as a visual calibration aid, not a photometer.
← → switch patterns
For accurate results keep browser zoom at 100% and test on the display you want to calibrate.
What each pattern checks
Set brightness so the darkest patch or two vanish into black while the next few near-black steps stay just visible.
A smooth black-to-white ramp with no sudden jumps, and dark detail near the left that is neither crushed nor raised to grey.
Even, distinct steps from black to white — each band should differ from its neighbours across the whole range.
A clean, uniform white field for perceived maximum brightness — check for dark corners, tint or uneven backlight.
A flat 50% gray field — look for blotches, banding or colour casts across the panel.
How to set your brightness
- Dim the room and turn off auto- or adaptive-brightness.
- Open the shadow-detail pattern and give your eyes a minute to adjust.
- Lower brightness until the 0 patch merges fully into black.
- Raise it just until the next near-black steps (1, 2, 4) become faintly visible.
- If every patch glows grey, brightness is too high — back it off until pure black looks black.
How to use this brightness test
Start the full-screen test and use the arrow keys (or click) to move between patterns. Work in the shadow-detail pattern first: it is the one the brightness control is meant to set. Dim the room, give your eyes a minute to adjust, then adjust brightness until the lowest near-black patches are just barely distinguishable from the pure-black surround. If the 0 and 1 patches glow grey, brightness is too high and blacks are raised; if the first several patches all vanish into black, brightness is too low and shadow detail is being crushed. Aim for the point where the darkest step or two disappear and the next few are faintly visible.
Brightness vs contrast: what each control does
On almost every monitor the Brightness control sets the black level — how much light the panel emits for the darkest signal — by shifting the whole image up or down, while the Contrast control sets the white level, or how bright the brightest signal is. Set brightness with a dark pattern so black stays black without swallowing detail, and set contrast with a bright pattern so white stays clean without clipping highlights. The two interact, so it usually takes a couple of passes. This tool focuses on overall luminance and shadow detail via the brightness control; use the sibling Black Level, Contrast, White Level and Gamma tests to fine-tune the rest of the tonal range.
How bright should your monitor be?
Screen luminance is measured in nits, also written cd/m² (candela per square metre). A common target for a typical office or living room is around 120 cd/m², with roughly 80–120 nits comfortable for a dim room and 150 nits or more useful in bright daylight. The goal is to match the screen to the light around it: a display that is much brighter than its surroundings is a frequent cause of eye strain and fatigue, and one that is too dim makes you lean in and lose shadow detail. Lower the brightness at night, raise it during the day, and let your eyes settle before judging — perceived brightness depends heavily on ambient light.
Adjusting brightness on Windows, Mac and the monitor OSD
- Windows laptop: Settings › System › Display › Brightness, or the brightness keys on the top row of the keyboard.
- Windows desktop: laptop-style sliders often do nothing on an external monitor — use the monitor’s own buttons (OSD) instead.
- macOS: System Settings › Displays, or the brightness keys; external displays may need their own hardware buttons.
- Monitor OSD: press the physical menu button, find Brightness (separate from Contrast), and adjust while this shadow-detail pattern is on screen.
- Turn off any “auto-brightness”, ambient-light or adaptive-brightness feature while testing so the panel does not change under you.