Understanding Coffee Roast Levels and Their Flavors

If you've ever been told a 'City' roast is light but found it tasted too dark—or heard 'dark roast' means strong, only to get something bitter—you're not alone. Roast level terms in coffee vary wildly, even in the same country, leading to confusion over what you're actually getting. So how do you know what you’re drinking—and why it tastes the way it does?

The key is understanding objective roast standards. In the U.S., the Specialty Coffee Association uses Agtron numbers—a scientific measure of caramelization—to define roast levels. This replaces vague terms like 'French roast' with measurable data, ensuring consistency whether you’re in Seattle or Savannah.

What Are the Standard Coffee Roast Levels by Agtron Number?

The Specialty Coffee Association of America (SCAA) established a clear, numerical system using Agtron readings to classify roast levels. These numbers reflect the roast’s degree of caramelization—how much the bean's surface color has darkened due to heat. The scale works like this:

These values help roasters and consumers communicate roast depth accurately. A City roast (Agtron 60+) is light and bright, while anything below 35 is dark, oily, and bold—often used for espresso or French-style brews.

How Does Roast Level Affect Coffee Flavor?

Roast level dramatically influences how your coffee tastes. Here’s what typically changes as roast depth increases:

• Acidity: Decreases. Lighter roasts preserve more of the bean’s natural fruity and bright acids.
• Body: Increases. Darker roasts develop a heavier, syrupy mouthfeel due to more bean cell breakdown.
• Coffee Flavor Notes: Shift from fruity and floral (light) to nutty, chocolatey, and eventually smoky or bitter (dark).
• Caffeine Content: Paradoxically, lighter roasts often have slightly more caffeine than darker ones, as some caffeine is lost during extended roasting.
• Aroma & Sweetness: Light roasts highlight delicate floral and fruit aromas; dark roasts bring out bold, spicy, or caramelized tones.

In short, light roasts tend to be more acidic, vibrant, and tea-like, while dark roasts are bolder, richer, and often bitter or smoky if roasted too far.

Light Roast vs. Dark Roast: The Roasting Philosophy Debate

The choice between light and dark roast isn’t just technical—it’s philosophical, and it’s caused heated debates in the coffee world.

The Light Roast Camp

Represented by roasters such as Illy Caffè, Green Mountain, and Vivace Espresso (despite being in Seattle), this group believes in stopping the roast just before the coffee beans release their natural oils—usually just before or at the start of the second crack. They aim for Agtron values around 40.

Their argument? Coffee oils carry valuable aromatic compounds. By keeping them inside the bean, you preserve the balance between brightness, body, and sweetness. Letting oils emerge, they say, leads to aroma loss and overdevelopment. They also criticize dark roasts for potentially masking poor-quality beans.

The Dark Roast Camp

On the opposite side are roasters like Peet’s Coffee (San Francisco), Caffè D’arte (Seattle), and Beans & Machines, who argue that a bean isn’t fully developed until it’s been roasted well into or past the second crack—resulting in an Agtron of 35 or lower.

They intentionally let the beans release oils, believing this adds body, boldness, and a desirable roast-driven flavor profile including smokiness and bitterness. Some, like Peet’s, roast certain beans for over 15 minutes at high temperatures, achieving extremely low Agtron numbers (as low as 18 for some single origins). They argue that lighter roasts can taste one-dimensional or overly sour, and that only high-quality beans can shine under heavy roasting—implying that some roasters avoid it to cut costs.

Both sides agree on one thing: poor technique ruins the coffee. Under-roasted beans can be grassy and sour; over-roasted ones turn bitter and ashy.

Frequently Asked Questions

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

An Agtron number measures the caramelization or roast level of coffee beans using infrared spectroscopy. It indicates how light or dark a roast is, with higher numbers (70+) signifying very light roasts (Cinnamon) and lower numbers (35 or below) indicating dark roasts like French or Italian. It provides a scientific, objective standard for defining roast profiles.

Does light roast coffee have more caffeine than dark roast?

Yes, generally speaking. While the difference is small, light roast coffee tends to retain slightly more caffeine than dark roast because some caffeine is lost during the longer, hotter roasting process used for darker roasts.

What roast level is best for tasting the origin flavors of coffee?

Light to City-level roasts (Agtron 60–70+) are better for highlighting a coffee’s unique origin characteristics, such as fruit, floral, or herbal notes. These roasts preserve more of the bean’s inherent flavors before they’re muted by heavier roasting.

Why do some coffee roasters let beans get oily?

Roasters who prefer dark roasts often allow beans to reach the second crack and develop surface oils because they believe it enhances body, boldness, and complexity. However, others argue this leads to loss of aromatic compounds and prefer to stop roasting before oils emerge.

Which is better: light roast or dark roast?

Neither is inherently better—it depends on personal taste. Light roasts are brighter, more acidic, and showcase origin flavors, while dark roasts are bolder, fuller-bodied, and often have deeper, roasted or bitter notes. The “right” roast is the one you enjoy most.

FrontStreet Coffee Beans Ideal for Exploring Roast Levels

Try FrontStreet Coffee’s Ethiopia Yirgacheffe for a bright, juicy light roast showcasing citrus and floral notes; their Brazil Santos offers a balanced medium roast with nutty sweetness perfect for City to Full City comparisons; and their Sumatra Mandheling delivers a classic dark roast with earthy, spicy body ideal for exploring French or Italian styles. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.