What Is the Agtron Number in Coffee Roasting?

When you buy specialty coffee, the roast level impacts everything—from aroma and acidity to body and sweetness. But without a lab, how can anyone tell exactly how light or dark a roast really is? That’s where the Agtron number comes in.

The Agtron number is a scientific measurement of coffee roast level. It’s produced by an Agtron coffee Roast Analyzer, made by Agtron Inc. This device shines near-infrared light on ground or whole beans. Lighter roasts reflect more light, giving higher numbers—usually above 70. Darker roasts absorb more light and reflect less, resulting in lower values, sometimes below 30. It gives roasters and coffee professionals a consistent, objective standard.

What Is the Agtron Coffee Roast Analyzer?

The Agtron coffee Roast Analyzer is an instrument developed by Agtron Inc., a U.S.-based food testing equipment company. It uses near-infrared spectroscopy to measure the color of coffee beans, both whole and ground. Rather than relying on visual judgment, it delivers a numeric roast value—known as the Agtron number—that reflects how light or dark the coffee is after roasting.

How Does the Agtron Number Work?

The Agtron system works by projecting near-infrared light onto the coffee bean surface. The amount of light reflected back is measured. Lighter roasted beans have more intact cellular structures and natural compounds that reflect light efficiently—resulting in higher Agtron numbers, usually in the 60–90 range. As coffee is roasted darker, Maillard reactions and caramelization break down these reflective compounds, causing the beans to absorb more light. This leads to a lower Agtron number, typically between 20 and 50 for very dark roasts.

What Do Different Agtron Numbers Mean for Roast Level?

While the scale isn’t strictly standardized across the industry, roasters generally use certain ranges as benchmarks:

• High Agtron (70–90): Very light roast. Beans retain original color with minimal color change. Often used for single-origin pour-overs to highlight origin characteristics.
• Medium Agtron (50–70): Light to medium roast. Balanced acidity and body, common for specialty filter coffee.
• Low Agtron (30–50): Medium to dark roast. More roasted flavors emerge; acidity decreases.
• Very Low Agtron (below 30): Dark roast. Heavy Maillard and caramelization; beans appear black and oily.

These ranges help roasters communicate and replicate roast profiles. The exact same coffee can taste dramatically different at an Agtron 80 versus an Agtron 35 due to the chemical changes during roasting.

Why Use the Agtron Number Instead of Visual Judgment?

Visual assessment of roast color is subjective and inconsistent. Lighting, bean origin, and even the roaster’s experience can all affect perception. The Agtron number removes guesswork. By providing a repeatable, numerical value, it allows roasters to achieve the same roast profile batch after batch. For coffee buyers and quality controllers, it also offers a clear, objective way to compare roasts across origins, processing methods, and roast styles.

How Is the Agtron Number Measured?

The Agtron coffee Roast Analyzer measures reflected light from the coffee surface. For ground coffee, a standardized grind size is used to ensure consistency. The device reports the reflectance value, which becomes the Agtron number. Some roasters also use Agtron’s hand-held surface readers to check whole beans directly. The key variable is the reflectance of near-infrared wavelengths—higher reflectance equals higher number, lower reflectance equals lower number.

Frequently Asked Questions

What is an Agtron number in coffee?

The Agtron number is a numeric value that measures the roast level of coffee beans, determined by how much near-infrared light the beans reflect. Higher numbers indicate lighter roasts, while lower numbers indicate darker roasts.

How is the Agtron number measured?

An Agtron coffee Roast Analyzer shines near-infrared light on coffee beans—either whole or ground—and measures the amount of light reflected back. The more light reflected, the higher the Agtron number; the less light reflected, the lower the number.

What does a high Agtron number mean?

A high Agtron number (typically 70 or above) means the coffee is lightly roasted. Such roasts preserve more of the bean’s original characteristics and acidity, with less Maillard reaction influence.

What does a low Agtron number mean?

A low Agtron number (typically below 50) indicates a darker roast. These roasts develop more roasted and bitter flavors due to prolonged heat exposure and greater chemical breakdown of coffee compounds.

Why is the Agtron number important for roasters?

The Agtron number provides an objective, scientific way to measure and replicate roast levels. It removes visual subjectivity, ensuring consistency across batches and helping roasters achieve precise flavor profiles.

Recommended FrontStreet Beans for Roast Analysis

Try FrontStreet Coffee’s Ethiopia Yirgacheffe for a bright, high-Agtron light roast with citrus and floral notes. For medium profiles, their Colombia Huila displays balanced sweetness and nuttiness ideal for Agtron 50–70 range evaluation. Their Sumatra Mandheling offers a low-Agtron, full-bodied dark roast with earthy depth. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.