Roasting is the process in which a green coffee bean is chemically transformed into the brown, aromatic bean we know. During roasting, Maillard reactions, caramelization of sugars and degradation of organic acids take place. The degree to which the process is carried out directly determines the character of the cup. The darker the roast, the stronger the roast notes and the weaker the origin notes.
The Agtron scale
Agtron is a spectrophotometer that measures bean reflectance using infrared light. The result is a number — the higher the number, the lighter the roast; the lower, the darker. The SCA has adopted the Agtron Gourmet scale as the classification standard.
Practical range for specialty coffee:
Agtron number
Roast level
Cup character
95–85
Very Light / Cinnamon
Pronounced acidity, fruitiness, grainy notes. Often underdeveloped, with grassy notes.
85–75
Light
Clear origin notes, accented acidity, floral and fruity character. Typical of Nordic roasters and most African coffees.
75–65
Light-Medium / Medium-Light
Balance between acidity and sweetness. Developed sweetness while keeping the origin character. The standard for most specialty filter coffees.
65–55
Medium
More body, the acidity calms down, notes of caramel, brown sugar and chocolate emerge. Often used for espresso in a specialty context.
55–45
Medium-Dark
Origin notes start to fade, caramel and dark chocolate dominate. Full body, muted acidity.
45–35
Dark
Roast notes take over — bitter chocolate, smoke, caramelized sugar. The character is lost.
35–25
Very Dark / French / Italian
Burnt, bitter, oils on the surface of the beans. Origin character is entirely absent; what you taste is the roaster itself.
The specialty edge
Specialty roasters rarely roast below Agtron 55. Below that line, the chemistry of roasting becomes more dominant than the inherent qualities of the bean — in other words, you’re no longer drinking Ethiopian coffee, you’re drinking “dark roasted” coffee. That’s why most specialty roasters work in the Agtron 90–60 range, with filter coffees in the 80–70 zone and espresso roasts in the 70–60 zone.
Light vs medium vs dark — what you get in the cup
Light roast preserves all of the bean’s complexity. Fruit, flowers, citrus, accented acidity. The body is usually lighter. The coffee behaves almost like tea — layered, clear, dynamic. Ideal for pour-over methods (V60, Origami, Kalita) where those layers stand out.
Medium roast is the balanced middle. Caramel sweetness, chocolate notes, mild fruit, calmed acidity. The body is full, but not heavy. Versatile — it works for pour-over, espresso and moka pot alike. The most popular zone for most specialty coffee drinkers.
Dark roast highlights itself — roast notes, smoke, bitter chocolate, caramelized sugar. The acidity is muted or absent. The body is full, often oily. Traditionally used for Italian espresso and commercial blends. In a specialty context it’s rare, because at that roast level the reason you bought a specialty bean in the first place gets lost.
A practical buying tip
When buying specialty coffee, the bag usually states the roast level (light, medium, medium-dark) or a specific Agtron value. If the bag mentions fruit, flowers, citrus and acidity — it’s probably in the Agtron 80–70 range. If you see chocolate, caramel, nuts — it’s probably 70–60.