Color Blind Test
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How it works

How the Color Blind Test Works

A plain-language guide to this colorblind test: how the dot plates are built, why each one targets a single cone type, how the adaptive staircase sets your scores, and how to read the result.

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Step by step

Taking the test

  1. Step 1

    Set up your screen

    Turn brightness to 100% and switch off night mode, blue-light filters, and True Tone. Sit about an arm’s length from the screen in normal room light, and take off sunglasses or any tinted lenses — unless you are deliberately testing with color correcting glasses.

  2. Step 2

    Read the warm-up plate

    The first plate hides an orange digit that stands out by brightness as well as color, so everyone should be able to read it. It checks that your screen and attention are working before the real measurement starts.

  3. Step 3

    Answer 18 adaptive plates

    Each plate is a circle of colored dots with one digit from 0 to 9 hidden inside. Tap or type the digit, or choose “Can’t see” if nothing stands out. You have 10 seconds per plate. Every right answer makes the next plate on that cone axis subtler; a miss makes it stronger.

  4. Step 4

    Read your cone scores

    At the end you get a 0–100 score for your red (L), green (M), and blue (S) cones and a screening verdict — normal, protan, deutan, red-green, or tritan — with mild, moderate, or strong severity. Results save on your device so you can compare later runs.

The method

What happens inside each plate

Your retina has three kinds of cone cells. Color blindness means one of them is missing or tuned differently. Instead of using fixed printed colors, every plate here is calculated so that only one cone type can see the digit.

  • Cone-isolating plates

    Inside each plate, the digit and background colors differ in the signal of only one cone type — L (long wavelength, “red”), M (medium, “green”), or S (short, “blue”). Someone missing that cone sees the two colors as identical, so the digit disappears. Someone with a weak cone needs more contrast before it pops out.

  • Brightness noise

    Every dot is given a random brightness. That hides the tiny luminance difference a color shift can carry, so the only way to read the digit is through color — the same trick used in the Cambridge Colour Test.

  • Adaptive staircase

    Each cone axis has seven contrast levels and starts at level three. A correct answer moves that axis one level subtler; a miss, timeout, or “Can’t see” drops it two levels. The three axes are interleaved in random order so you cannot anticipate which one comes next.

  • Scoring

    A cone score is where that axis’s staircase settles over its last three steps, expressed from 0 (needed the strongest contrast and still missed) to 100 (read the subtlest plates). Scores of 80 and above are typical. The verdict comes from your lowest axis.

  • What it is not

    This is a screening test on an uncalibrated consumer display. It is useful for spotting a likely deficiency and its type, but it is not a medical diagnosis and should not be used for occupational or licensing decisions.

Your result

Score bands

Each cone gets its own score. The verdict names the lowest axis: red means a protan pattern, green deutan, blue tritan. See types of color blindness for what each one looks like day to day.

80–100Typical
You read the subtle plates on this cone axis. People with normal color vision usually land here on all three scores.
60–79Mild
You needed a little more color contrast than typical. On a red or green axis this is the pattern of mild protanomaly or deuteranomaly; retest on another screen to confirm.
35–59Moderate
Clearly reduced sensitivity for this cone type. Many everyday color pairs — red and brown, green and orange, blue and purple — will be harder to tell apart.
0–34Strong
Even the strongest plates on this axis were hard to read. This matches dichromacy (protanopia, deuteranopia, or tritanopia) or a strong anomalous trichromacy.

Controls

Answering plates

  • Phones & tablets

    Tap the keypad

    A 0–9 keypad sits directly under the plate with a wide “Can’t see” key. Each tap answers immediately — there is no submit step — and the next plate appears with no page reload.

  • Desktop

    Keyboard

    Press 0–9 to answer, Space or X for “Can’t see”, Esc to quit, R to restart, and M to mute. Enter starts a test from the intro or results screen. All buttons have visible focus rings.

  • Every plate

    Timer ring

    An amber ring around the plate drains over 10 seconds and the counter beeps for the last three. A plate that runs out counts as “Can’t see”, which mirrors how a clinician would treat a long hesitation.

Getting a result you can trust

  • Set screen brightness to maximum and turn off night shift, True Tone, and blue-light filters before you start.
  • Take the test in normal indoor light — avoid direct sun on the screen and very dark rooms.
  • Look at the whole plate for a second rather than hunting dot by dot; the digit appears as a shape, not a pattern.
  • Answer “Can’t see” honestly. Guessing adds noise but cannot raise a score for long, because the staircase checks again.
  • Retake on a second device. A result that repeats on two screens is far more trustworthy than one run.
  • Testing color correcting glasses? Do one run without them and one with them, then compare in History.

Questions about accuracy, glasses, or devices are answered in the FAQ.

Take the color blind test