Contrast test
A monitor that looks punchy is often just throwing away detail. Two ladders of nearly identical patches will tell you how much of the shadow and highlight range your screen can actually show, and how much it is quietly discarding.
The test opens full screen. Space — next · Arrow keys — back and forward · Esc — exit
Your browser blocked full screen. The test still works in this window, but a full-screen view is more reliable — try pressing F11.
Could you tell every patch apart on both ladders?
How to read the two ladders
The test shows two ladders. Press space to switch between them.
The black ladder is a row of very dark grey patches on a black background, labelled with their brightness value from 1 to 20. Count how many you can distinguish from the background and from each other.
The white ladder is the mirror image: near-white patches on white, from 254 down to 235.
Give each one about ten seconds. Near-black separation in particular takes a moment for your eyes to resolve, and the first glance always undercounts.
What the count tells you
| Result | What it means | What to do |
|---|---|---|
| All patches visible on both | Correctly adjusted | Nothing |
| Bottom 2–4 black patches invisible | Mild black crush | Raise brightness or black level slightly |
| Bottom 5+ black patches invisible | Heavy black crush | Turn off dynamic contrast, check gamma |
| Top 2–4 white patches invisible | Mild highlight clipping | Lower contrast a few steps |
| Top 5+ white patches invisible | Heavy clipping | Lower contrast; if it does not move, see below |
| Both ends collapsed | A picture mode, or a range mismatch | Try Standard or sRGB mode; if unchanged, see below |
When it is not the monitor at all
If both ends collapse at once, and the cliff does not move when you change the brightness, this is not a monitor setting. It is the graphics card and the screen disagreeing about where black and white sit in the signal — full range at 0 and 255, or limited range at 16 and 235 — and the detail is being discarded before the panel receives it.
That has its own signature and its own settings on both the driver and the display, which the RGB range test finds: it looks for a cliff at exactly 16 and exactly 235, where this page only counts how many steps survive.
macOS
macOS handles range automatically over DisplayPort and Thunderbolt, and usually gets HDMI right too. When it does not, the symptom is washed-out blacks on an external monitor:
- Check the monitor own HDMI black level setting first and set it to Normal or Full.
- Colour profile matters more on macOS than range does. System Settings → Displays → Colour profile: pick the profile that matches the display, not a generic one.
- Turn off True Tone before judging either ladder.
Before you adjust anything
Set the monitor back to its default picture mode first. Dynamic contrast, game modes, black equalizer, shadow boost and similar features all alter the mapping between signal and light, and any one of them will make this test meaningless. Get a clean result in Standard or sRGB mode, then re-enable whatever you like the look of.
Common questions
What is black crush, and is it the same as black clipping?
The same fault under two names. Everything below a certain brightness renders as the same flat black, so detail that exists in the source — the folds of a dark jacket, objects in a shadowed corner of a game — is simply not shown. Reviews tend to say black crush, measurement tools tend to say black clipping, and the control that causes it is called Black Level on some monitors and Brightness on others, which is worth knowing before you go looking in the menu. It comes from that control being set too low, from an aggressive contrast or dynamic contrast mode, or from a gamma setting that does not match the content.
What is white clipping?
The same fault at the other end: everything above a certain brightness renders as identical pure white. Clouds lose their shape, highlights on metal turn into flat patches. It usually comes from the contrast control being pushed too far — or, when both ends collapse together and no adjustment moves them, from the signal and the screen disagreeing about full and limited range, which the RGB range test settles.
How many patches should I be able to see?
On a well-adjusted monitor, all of them on both ladders, though the darkest one or two take some looking for in a bright room. If you are missing three or more at either end, something is wrong with the settings rather than your eyes.
Does this test measure my contrast ratio?
No, and no browser test can. Contrast ratio is a measurement of luminance, and that needs a colorimeter held against the screen. What this test measures is how much of the range survives to your eye, which is the thing that actually affects what you see — and it is often the more useful of the two.
Why do the dark patches look different on my phone?
Phones apply automatic brightness and, on OLED, their own tone mapping. An OLED phone will usually show more of the dark ladder than an LCD monitor, because its black is genuinely black. Turn auto-brightness off before comparing two devices.