Roast Color Agtron Scale

The Roast Color Agtron Scale is the industry standard for objectively measuring roast color. Developed by the Agtron company, this system uses a spectrophotometer to measure the amount of light reflected off a sample of ground coffee. The resulting number—the 'Agtron number'—provides a precise, numerical value for the roast level, removing the subjectivity of visual inspection.

On the Agtron scale, lower numbers indicate darker roasts (less light reflected), while higher numbers indicate lighter roasts (more light reflected). For example, a light roast might fall in the 70–80 range, while a dark, oily French roast might be in the 30–40 range. This scale is invaluable for roasters who need to ensure that every batch of a specific coffee tastes the same, regardless of who is operating the machine.

In practice, the Agtron scale is used for quality control and sensory calibration. By measuring the Agtron number of a production roast against a 'gold standard' sample, roasters can verify that their roast profile is being replicated accurately. It is also used in competitions, such as the Cup of Excellence, to ensure that all coffees are roasted to a standard level for fair evaluation by the judges.

For the consumer, the Agtron scale is a behind-the-scenes tool that ensures the coffee you buy is consistent. While you won't see these numbers on most retail bags, they are the reason why your favorite single-origin coffee tastes the same from one month to the next. It is a prime example of how science and technology are used in the specialty coffee industry to maintain the highest standards of quality and consistency from the roastery to your cup.