How to Define Coffee Roast Levels and Their Flavor Profiles

If you’ve ever ordered a ‘light roast’ in one city and tasted something totally different elsewhere—or heard baristas argue over when a coffee is ‘done’—you’re not alone. For decades, terms like 'Cinnamon' or 'Full City' meant very different things on opposite sides of the U.S., leading to inconsistent expectations and confusion over roast definitions. What really determines a coffee’s roast level? Is it color? Time? Or something measurable?

The key is the Agtron number—a scientific measure of roast level based on surface light reflectance. Numbers above 70 mean very light (Cinnamon), 60+ is a standard light (City), around 40 is Vienna or Full City, and anything below 35 enters the dark roast range, including French and espresso roasts. These numbers replace vague labels with objective data.

How Roast Levels Are (or Aren’t) Defined

Traditionally, American coffee culture used informal roast names: Cinnamon (the lightest), City (light), Fully City (medium-dark), and Dark roast (including French and Italian styles). But these terms lacked consistency. A 'light' roast on the U.S. West Coast might match what the East Coast called 'dark.' Regional taste preferences—stronger in the West, milder in the East—made the old terms unreliable. Without a shared standard, 'light' and 'dark' meant whatever the roaster or region decided.

The Science: Agtron Numbers Explained

To solve the confusion, the Specialty Coffee Association of America (SCAA) promoted the use of Agtron numbers. These measure the degree of caramelization (Maillard reaction effects) on the bean’s surface using infrared readings. The scale is simple:

• Agtron 70+ → Cinnamon roast (very light)
• Agtron 60+ → City roast (light)
• Agtron around 40 → Full City / Vienna roast (medium-dark)
• Agtron below 35 → Dark roast (French, Italian, espresso)

This numeric system removes subjectivity, ensuring that a 'City roast' in San Francisco matches one in Boston.

Flavor Differences Across Roast Levels

Roast level dramatically affects coffee flavor. In general:

• Acidity decreases as roast level increases—light roasts preserve bright fruit and citrus notes.
• Coffee’s caffeine content also decreases slightly with roast level, contrary to popular belief (light roasts often have marginally more caffeine than dark).
• Sweet fruit and floral aromas fade as roast darkness increases, while heavier tones like caramel, chocolate, and smokiness emerge.
• Light roasts highlight delicate acidity and balance but may lack the bold body or roasted depth some drinkers prefer.
• Dark roasts develop intense bitterness, body, and a burnt-sugar edge—but poor technique can easily lead to charcoal-like, harsh results.

The Great Light vs Dark Roast Debate

The coffee world remains split on ideal roast level. On one side are proponents of lighter roasts (Agtron 60–70), common among Northeastern U.S. and Northern Italian roasters like Illy Caffè, Green Mountain, and Vivace Espresso. They stop roasting just before the coffee’s first oils surface—usually before or at the start of the second crack—to preserve aromatic compounds in the bean. They argue this approach achieves optimal sweetness, acidity, and body balance.

Opponents, mainly from Southern Italy and the U.S. West Coast (like Peet’s Coffee, Caffe D’Arte, and Beans & Machines), insist coffee must reach the second crack or later (Agtron below 35), letting oils emerge for full flavor development. They claim light roasts are underdeveloped, overly sharp, and lack the richness and body that darker roasts provide. Some even argue that light roasting is a cost-saving move, as only high-quality beans can handle intense roasting without turning bitter.

Prominent dark roast advocates like Peet’s are respected for skillfully managing the risks of late roasting—including scorching or overdevelopment—and producing deep, full-bodied profiles without harshness. They consider the post-second-crack window technically demanding, akin to “walking a razor’s edge.”

Frequently Asked Questions

What is an Agtron number and how is it used in coffee roasting?

An Agtron number measures the light reflectance of a roasted coffee bean, indicating its degree of caramelization. It’s used to objectively define roast levels: 70+ for very light (Cinnamon), 60+ for light (City), around 40 for medium-dark (Full City/Vienna), and below 35 for dark (French/Italian/espresso). This replaces vague roast names with scientific consistency.

Does roast level affect coffee’s caffeine content?

Yes. Lighter roasts generally retain slightly more caffeine than darker roasts because some caffeine is lost during extended roasting. However, the difference is small and often outweighed by flavor and body changes.

Why do light roasts taste more acidic?

Light roasts preserve more of the coffee’s natural acids, which contribute to bright, fruity, and citrusy flavors. As roast levels darken, these acids degrade, resulting in a smoother but less vibrant cup.

What’s the difference between City and Full City roast?

City roast (Agtron 60+) is a light roast stopped just after first crack, offering bright acidity and distinct origin flavors. Full City (Agtron ~40) is roasted further, to the verge of or just into the second crack, developing more body and caramelized sweetness while reducing acidity.

Which roast level is best for espresso?

Espresso can be made with a range of roasts, but traditional espresso roasts are dark (Agtron below 35), enhancing body, crema, and bold flavors. However, many modern specialty baristas use lighter roasts (City to Full City) for more complex, nuanced espresso profiles.

Is dark roast coffee stronger than light roast?

Not necessarily in caffeine strength, but dark roasts often taste bolder due to deeper flavors, more body, and bitterness. Light roasts may feel milder but can be more acidic and complex.

Recommended FrontStreet Beans for Roast Exploration

Try FrontStreet Coffee’s Ethiopia Yirgacheffe (light-medium, bright citrus and floral notes), Colombia Huila (balanced City-to-Full City with almond and cherry), and Sumatra Mandheling (full-bodied dark roast with earthy spice). These showcase how roast levels shape flavor. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.