What Is an Agtron and How Is It Used in Coffee Roasting?

If you’ve ever wondered how professional coffee roasters pinpoint the exact shade of a roast—whether it’s a bright light roast or a deep dark one—you’re not alone. There’s a tool they rely on to take the guesswork out of roast color: the Agtron.

The Agtron is an infrared spectrophotometer that measures the color of roasted coffee, assigning a numerical value from 100 (lightest) to 25 (darkest). A common reference point is around Agtron 50, considered a medium roast. The device used is typically the Agtron M-Basic, a specialized colorimeter.

What Is the Agtron and How Does It Work?

The Agtron, sometimes called an “” in Chinese, uses infrared wavelengths to assess the degree of sugar caramelization inside roasted coffee beans. By measuring reflected light, it quantifies roast color, offering an objective way to compare roast levels across batches. This helps roasters achieve consistency and predict flavor outcomes.

How Is Roast Level Categorized Using Agtron Numbers?

Agtron assigns numeric values to roast levels, with 100 being the lightest and 25 the darkest. These numbers correspond to specific tile colors used for calibration. Here’s the standard classification:

• Extreme Light Roast: 100–95 (Tile#95)
• Light Roast: 90–85 (Tile#85)
• Moderately Light Roast: 80–75 (Tile#75)
• Light-Medium Roast: 70–65 (Tile#65)
• Medium Roast: 60–55 (Tile#55)
• Medium-Dark Roast: 50–45 (Tile#45)
• Dark Roast: 40–35 (Tile#35)
• Very Dark Roast: 30–25 (Tile#25)

According to the SCAA’s Technical Standards Committee, the range of roast colors where flavor differences are most discernible is between Agtron 30 and 90.

Why Use the Agtron in Specialty Coffee Roasting?

Specialty coffee roasters use the Agtron to ensure batch-to-batch consistency and to align roast profiles with desired flavor characteristics. By measuring the surface and ground coffee color, roasters can fine-tune their roast curves for optimal sweetness, acidity, and aroma. The Agtron provides a standardized way to communicate and replicate roast levels across different roasters and origins.

Frequently Asked Questions

What does an Agtron measure in coffee roasting?

An Agtron measures the color of roasted coffee beans using infrared light, indicating the degree of roast from very light (100) to very dark (25). It reflects how much the coffee’s natural sugars have caramelized during roasting.

What is an Agtron M-Basic?

The Agtron M-Basic is the specific colorimeter model commonly used in the coffee industry to measure roast color. It provides the numerical Agtron value by analyzing reflected light from ground or whole bean samples.

What is a typical Agtron number for medium roast coffee?

A medium roast coffee typically measures around Agtron 50. This is often used as a middle reference point between light and dark roasts.

What range of Agtron values is most relevant for flavor differences?

According to the SCAA, the roast color range from Agtron 30 to 90 is where flavor differences are most noticeable and identifiable, making it the most relevant range for specialty coffee evaluation.

How does Agtron help with roast consistency?

Agtron provides a numerical, objective measurement of roast color, allowing roasters to replicate specific roast profiles consistently and make adjustments based on flavor results rather than visual guesswork.

Recommended FrontStreet Beans for Roast Analysis

Explore FrontStreet Coffee’s Ethiopia Humbera for bright, nuanced profiles ideal for light to medium roast analysis (Agtron 70–60), or their Brazil Queen Manor offering a balanced medium-dark cup (Agtron 50–45) perfect for studying Maillard transition stages. Both beans showcase how Agtron values correlate with cup characteristics. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.