The Farnsworth D-15 is a color arrangement test: you put 15 colored caps in order of hue, starting from a fixed reference cap. How you arrange them reveals your color vision — people with typical vision follow the color circle, while people with a deficiency confuse caps on opposite sides of their confusion axis. Unlike a screening plate test, the D-15 classifies the TYPE (protan, deutan, or tritan) and separates significant deficiencies from mild ones. This free online version scores your arrangement with the Vingrys & King-Smith method and shows the classic color-circle diagram. It is a self-check, not a diagnosis: it detects moderate and stronger deficiencies well, very mild cases can pass, and an uncalibrated screen shifts the absolute thresholds.
Color arrangement · classifies the type
Farnsworth D-15 Test
Arrange 15 colored caps in hue order to explore which colors you confuse. This online self-check gives an estimated confusion pattern.
Also available in: Español · Português · Italiano
How the D-15 test works
1. Arrange the caps
Starting from the fixed reference cap, tap the colored cap that looks closest to it, then the closest to that one, and so on — building a chain of 15 caps in order of hue. There's no time pressure; sort by color, not brightness.
2. We plot your order
Your arrangement is drawn on the color circle. A color-normal arrangement follows the rim of the circle. A color vision deficiency produces lines that cut straight across the circle — confusions between colors that sit on opposite sides of your confusion axis.
3. Type & severity
We score the arrangement with the Vingrys & King-Smith method: a confusion index measures how far your order departs from perfect, and the direction of your confusions estimates the type — protan (red), deutan (green), or tritan (blue-yellow). On an uncalibrated screen these are estimates, not a diagnosis.
What the D-15 test can and cannot tell you
Classifies the type. Protan (red), deutan (green), or tritan (blue-yellow) — read from the direction of your confusions.
Finds meaningful deficiencies. Separates moderate and strong deficiencies from normal or very mild vision.
Not sensitive to mild anomalies. To screen for those, use the Ishihara or HRR plate tests.
Treat it as a self-check. Absolute cutoffs need a calibrated screen — confirm anything important with an eye-care professional.
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 D-15 — frequently asked questions
- What is the Farnsworth D-15 test?
- The Farnsworth D-15 (dichotomous) test is a color arrangement test. The person orders 15 colored caps by hue, starting from a fixed reference cap. The way the caps are arranged is plotted on a color circle and scored to classify the type of color vision deficiency (protan, deutan, or tritan) and to separate significant deficiencies from mild ones.
- How is the D-15 different from the Ishihara test?
- The Ishihara test is a screening test — it tells you whether a red-green deficiency is likely present, using hidden-number plates. The D-15 is a classification test — you arrange colors, and the pattern of your arrangement shows which type you have and roughly how significant it is, including blue-yellow. Many clinics use a plate test to screen and the D-15 to classify.
- How is the D-15 scored?
- Each cap has a known position on the color circle. We measure the color-difference vectors between the caps in the order you placed them and compute a confusion index (1.0 is a perfect arrangement; higher means more confusions) and a confusion angle (its direction estimates the type). This is the Vingrys & King-Smith moment-of-inertia method. The classic Farnsworth method instead counts the number of lines that cross the circle diametrically.
- Can the D-15 detect mild color blindness?
- Not reliably. The D-15 is designed to separate people with significant (moderate or strong) color vision deficiency from those with normal or very mild vision, so a person with a mild anomaly often passes it. To screen for a mild red-green deficiency, a plate test such as the Ishihara or HRR is more sensitive.
- Is this online D-15 accurate?
- It reliably shows the pattern and direction of significant arrangement errors, so the type estimate and the relative confusion index are meaningful. But an uncalibrated screen and room lighting shift the absolute pass/fail threshold, so treat the result as a self-check and confirm anything important with an eye-care professional using a calibrated, standardized test.