Farnsworth D-15 Color Blind Test

Arrange 15 colored caps in chromatic order to reveal the type and severity of your color vision deficiency. This classic dichotomous test screens for protan, deutan, and tritan defects.

Farnsworth D-15 Test

Arrange 15 colored caps in chromatic order to screen for protan, deutan, and tritan color vision deficiency.

•Drag a colored cap from the top row into an empty slot below
•Or click to select a cap, then click a slot to place it
•Click or drag a placed cap back to the top row to undo it
•Arrange all 15 caps to create a smooth color gradient

What is the Farnsworth D-15 Test?

The Farnsworth Dichotomous Test for Color Blindness (D-15) was developed by Commander Dean Farnsworth of the U.S. Navy in 1947. It is a simplified version of the Farnsworth-Munsell 100 Hue Test designed as a quick "pass or fail" screening tool to separate individuals with moderate to severe color vision deficiency from those with normal or mildly deficient color vision.

The test uses 15 colored caps (plus one fixed reference cap) whose hues span a complete circle in the Munsell color system at approximately Value 5, Chroma 4. The subject's task is to arrange the 15 loose caps in the order that makes the smoothest possible color progression starting from the reference cap.

Unlike the Ishihara test which only screens for red-green deficiency, the D-15 can detect and classify all three major types of color vision deficiency: protan (red-weak), deutan (green-weak), and tritan (blue-weak). The pattern of errors on the D-15 circle diagram reveals which confusion axis the subject follows.

How to Take the Test

1. Select a Cap

Click a colored cap from the available caps row. The cap will be highlighted to show it's selected. Choose the color that looks most similar to the last placed cap.

2. Place in Order

Click an empty slot in the arrangement row to place the selected cap. Build a smooth color gradient starting from the blue reference cap. You can click a placed cap to return it.

3. View Results

After placing all 15 caps, submit your arrangement. You'll receive a D-15 circle diagram showing your error pattern and a diagnosis of any color vision deficiency.

D-15 vs. Farnsworth-Munsell 100 Hue Test

Both tests were developed by Dean Farnsworth and require the subject to arrange colored caps in chromatic order. However, they serve different clinical purposes:

D-15 (This Test)

- 15 caps + 1 reference
- Pass/fail screening tool
- Detects moderate–severe deficiency
- Classifies type: protan, deutan, or tritan
- Takes 2–5 minutes
- Used for occupational screening

FM100 Hue Test

- 85 caps across 4 trays
- Quantitative scoring
- Detects even mild deficiency
- Measures hue discrimination ability
- Takes 10–20 minutes
- Used for research and detailed assessment

The D-15 is designed to catch moderate and severe deficiencies that could affect daily tasks. If you pass the D-15, it does not guarantee perfect color vision — mild anomalous trichromacy may go undetected. For a more sensitive assessment, take the FM100 Hue Test.

How the D-15 Scoring Works

The D-15 uses a circle diagram with 16 positions arranged clockwise — the reference cap plus 15 test caps. After you submit your arrangement, lines are drawn between consecutive caps on the diagram:

Normal vision: Lines connect adjacent positions on the circle, forming a smooth polygon that follows the perimeter.
Color deficiency: Lines cross the interior of the circle along characteristic "confusion axes" — the directions in color space where a person with that deficiency confuses colors.

The three confusion axes correspond to the three types of cone photoreceptor deficiency:

Protan Axis

Confusion between blue-green and red-purple. L-cone (red) deficiency.

Deutan Axis

Confusion between green and red-purple. M-cone (green) deficiency.

Tritan Axis

Confusion between blue-green and yellow-pink. S-cone (blue) deficiency.

Saturated vs. Desaturated Mode

This test offers two difficulty levels by varying the color saturation of the caps:

Saturated (Standard)

Vivid, deeply colored caps matching the original D-15 test. This is the standard clinical version. Most people with normal color vision will easily arrange these correctly. Errors here indicate moderate to severe color vision deficiency.

Desaturated (Adams D-15d)

Pale, washed-out caps with reduced chroma. This is the desaturated version developed by Adams, Courage, and Merigan as a more sensitive screening tool. It can detect milder forms of color vision deficiency that pass the standard D-15.

We recommend starting with the Saturated mode. If you pass, try the Desaturated mode for a more sensitive screening.

Sources

Farnsworth, D. (1943). "The Farnsworth-Munsell 100-Hue and Dichotomous Tests for Color Vision." Journal of the Optical Society of America, 33(10), pp. 568-578.
Vingrys, A.J. & King-Smith, P.E. (1988). "A quantitative scoring technique for panel tests of color vision." Investigative Ophthalmology & Visual Science, 29(1), pp. 50-63.
Adams, A.J., Courage, M.L. & Merigan, W.H. (1988). "The desaturated Lanthony D-15 panel test: a modification of the Farnsworth D-15 test."
Birch, J. (1997). Diagnosis of Defective Colour Vision, 2nd ed. Butterworth-Heinemann. — Standard reference for clinical color vision testing and D-15 interpretation.
National Eye Institute (NEI) — Overview of color blindness types, causes, and diagnosis.

Frequently Asked Questions

The Farnsworth D-15 (Dichotomous) test is a color arrangement test developed in 1947 by Dean Farnsworth. You arrange 15 colored caps in chromatic order starting from a fixed reference cap. The pattern of errors reveals whether you have protan (red-weak), deutan (green-weak), or tritan (blue-weak) color vision deficiency, and how severe it is.

The D-15 uses 15 caps and serves as a quick pass/fail screening tool for moderate to severe deficiency. The FM100 Hue Test uses 85 caps across 4 trays and provides a quantitative score of your overall hue discrimination ability. The D-15 takes 2-5 minutes while the FM100 takes 10-20 minutes. The D-15 classifies the type of deficiency, while the FM100 measures the degree of color discrimination.

The circle diagram plots 16 positions (reference + 15 caps) in their correct order around a circle. Lines connect your caps in the order you placed them. If you have normal vision, the lines follow the circle's perimeter. If you have a color deficiency, the lines cross through the center along a characteristic 'confusion axis' — protan, deutan, or tritan.

The saturated mode uses vivid colors matching the original D-15 test — it detects moderate to severe deficiency. The desaturated mode uses pale, washed-out colors (based on the Adams/Lanthony D-15d variant) and is more sensitive, able to detect milder forms of color vision deficiency that pass the standard test.

Yes. The standard D-15 is designed as a 'dichotomous' test — it separates moderate/severe deficiency from normal and mild. People with mild anomalous trichromacy often pass the D-15 because the color differences between adjacent caps are large enough for them to discriminate. Use the desaturated mode or the FM100 Hue Test for a more sensitive assessment.

No. This is a screening tool only. The clinical D-15 uses physical Munsell color caps under standardized D65 illumination (daylight). Screen color reproduction varies between devices and cannot match the precise Munsell chromaticities. If you need a certified color vision assessment, consult an optometrist or occupational health professional.