The Farnsworth-Munsell 100 Hue test measures how finely you can tell colors apart. You arrange 85 colored caps into a smooth hue order across four boxes; the test scores how close your order is to the true hue circle. It is the classic fine color-discrimination test — more sensitive than a pass/fail screen — and gives a Total Error Score (lower is better, 0 is perfect) plus a polar plot showing which hues you confuse, which estimates the type (protan, deutan, or tritan). This free online version is faithful to the method but is very sensitive to screen calibration, so treat the score as relative and the type as an estimate. It is a self-check, not a diagnosis.
Color arrangement · fine discrimination
Farnsworth-Munsell 100 Hue Test
Arrange 85 colored caps into smooth hue sequences to measure color discrimination. Your score depends on your screen and viewing conditions.
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How the 100 Hue test works
1. Arrange each box
The hue circle is split into four boxes, each between two fixed reference caps. Starting from the left reference cap, tap the colored cap that looks closest to it, then the closest to that, building a smooth color gradient toward the right reference cap.
2. We score your order
For every cap we add up how far its neighbors sit from it on the true hue circle. A perfect order scores 0; each misplacement adds to the Total Error Score (TES). We also take the square root of the TES, the conventional age-comparable statistic.
3. Read the polar plot
Your per-cap errors are plotted around the hue circle. A near-circular shape means even discrimination. Two bulges on opposite sides reveal the hues you confuse most; the axis through them estimates the type. On an uncalibrated screen, treat type and degree as estimates.
What the 100 Hue test can and cannot tell you
Measures fine color discrimination. A graded error score around the full hue circle — not just pass/fail.
Estimates the type. Protan, deutan, or tritan — read from the axis where your confusions cluster.
Not a quick screen. It's long, and very sensitive to screen calibration — treat the score as relative, not an absolute norm.
Not a tetrachromacy test. A strong score means good hue discrimination, not a fourth cone type — and the 1993 study that looked for a carrier signal on this very test could not find one. See why no screen can confirm tetrachromacy.
What does your score mean? See the FM-100 scoring guide — the Total Error Score arithmetic, Farnsworth's bands and the published norms for every age.
Want a faster answer? For a fast yes/no screen, use the Ishihara or HRR test; to classify the type, the D-15 is quicker.
This is a free screening and self-assessment tool, not a medical diagnosis. Results are affected by your screen, its color settings, and room lighting.
Farnsworth-Munsell 100 Hue — frequently asked questions
- What is the Farnsworth-Munsell 100 Hue test?
- It is a color arrangement test that measures fine color discrimination. You order 85 colored caps (in four boxes) by hue, and the arrangement is scored to produce a Total Error Score and a polar plot. Unlike a screening test, which gives a yes/no answer, the 100 Hue test grades how well you discriminate close hues and shows where your discrimination is weakest.
- How is the 100 Hue test scored?
- Each cap's error is the sum of the differences between its cap number and its two neighbors' numbers. A perfect arrangement scores 0; every misplacement adds to the Total Error Score (TES). Lower is better. The square root of the TES is used to compare against age norms, because raw scores are skewed and vary with age.
- What is a good 100 Hue score?
- On the standard test, roughly: a Total Error Score under about 16 is superior discrimination, about 16–100 is average, and over 100 is low discrimination — but normal scores rise in children and older adults, so age matters: the published norms put the mean at about 44 for a 20-year-old and about 90 for a 12-year-old or a 55-year-old. Our FM-100 scoring guide lists the full age table. Because this is an uncalibrated online version, read your score as relative for self-tracking rather than a clinical grade.
- Does it detect the type of color blindness?
- It can estimate it. People with a color vision deficiency confuse hues along their confusion axis, which shows up as two bulges on opposite sides of the polar plot. The orientation of that axis estimates protan, deutan, or tritan. Mild cases and protan-versus-deutan calls are less certain, especially on an uncalibrated screen.
- Does a very good score mean I am a tetrachromat?
- No, and this is worth being clear about because arrangement tests get passed around as "tetrachromacy tests". A low Total Error Score means you separate close hues well — which reflects practice, attention, lighting and screen quality as much as biology. Tetrachromacy is something else: a fourth cone class with its own spectral sensitivity. It cannot be demonstrated on a display at all, because separating a tetrachromat requires two lights that look identical to a trichromat but differ at that fourth cone, and a screen with three primaries cannot generate such a pair. Identifying it for real takes genetic testing plus a laboratory color-matching task — and the functional form is rarer than popular articles suggest: in one published series of 24 women carrying the relevant genes, a single participant behaved tetrachromatically (Jordan, Deeb, Bosten & Mollon, Journal of Vision, 2010).
- Why is the 100 Hue test so sensitive to my screen?
- It relies on telling apart very close hues, so small color errors from an uncalibrated display, brightness, or room lighting change the result more than they would for a coarse screening test. Set full brightness, turn off night-shift, and use a neutral room — and still treat the score as relative. For a calibrated measurement, the physical test under standard lighting is the reference.