How Roast Levels Are Measured in Specialty Coffee

Ever wondered why your 'light roast' from one cafe tastes completely different from another’s — or why 'dark roast' seems to mean something totally different on either coast of the U.S.? The truth is, until recently, most roast level terms were more opinion than science. If you've ever been confused by what 'city', 'full city', or 'French roast' really means, you're not alone.

The key to understanding roast levels today is the Agtron number — a scientific measurement of coffee bean color and caramelization that removes the guesswork. Numbers 70+ indicate very light roasts, while 35 or below means dark or French roast. That’s how pros now define roast consistently across the board.

What Are the Standard Roast Levels by Agtron Number?

The Specialty Coffee Association of America (SCAA) established an Agtron-based roast classification system that uses infrared readings to measure the degree of bean caramelization. This provides objective, numerical values for common roast levels:

• Cinnamon roast (very light): Agtron 70+
• City roast (light): Agtron 60+
• Full City / Vienna roast (medium): Agtron around 40
• French / Espresso roast (dark): Agtron 35 or below

These numbers replace vague regional terms and allow roasters and consumers to speak a common language about roast degree. No more confusion over whether 'city' in California means the same as 'city' in New York.

How Does Roast Level Affect Coffee Flavor?

Different roast levels dramatically change the taste, aroma, and body of your coffee:

• Acidity is higher in lighter roasts and decreases as roast level darkens — if you love bright, fruity, or citrusy notes, go lighter.
• Coffee acidity and caffeine both decrease slightly with darker roasts. Surprisingly, lighter roasts often retain marginally more caffeine.
• Fruit and floral aromas fade as roasting progresses, while darker roasts develop deeper tones like caramel, chocolate, smokiness, and a fuller body.
• Roast development impacts mouthfeel: lighter roasts may show more origin character but can taste thin or sharp if underdeveloped, while darker roasts offer more richness but risk being bitter or burned if poorly executed.

The Great Light vs Dark Roast Debate

The question of which roast level is 'better' sparks passionate debate in the coffee world. Opinions divide sharply along regional and philosophical lines:

The Light Roast Camp (North Italy, East Coast USA)

This group includes roasters like Illy Caffe, Green Mountain, and Vivace Espresso. They typically roast to an Agtron around 40, stopping just before or at the start of the coffee bean’s second crack — or just before oils rise to the surface.

Their philosophy:

• Preserve aromatic compounds stored in coffee oils by not letting them migrate to the bean surface.
• Maximize balance between fruit acidity and sweetness.
• Achieve optimal body and a sweet, lingering finish.

They argue that letting oils rise to the surface means losing valuable aromatics — and that dark roasting is often a way to mask flaws in lower-grade beans.

The Dark Roast Camp (Southern Italy, West Coast USA)

Notable proponents include Peet’s Coffee, Caffe D’Arte, and Beans & Machines. Their espresso roasts often measure below Agtron 35 — some single origins even hit Agtron 18, like their Antigua offering.

Their approach:

• Roast well into or through the second crack, allowing oils to emerge on the bean surface.
• Believe this develops deeper flavors including bold body, smoky richness, and a more intense finish.
• Argue that lighter roasts can taste one-dimensional or overly acidic, especially when using lower-quality beans.

They also emphasize the technical challenge of roasting beyond the second crack — calling it the “razor’s edge” of coffee roasting — and claim that only skilled roasters can avoid burning the beans at these levels.

So, Which Roast Level Is Right for You?

There’s no universal answer. Light roasts highlight origin characteristics, acidity, and floral or fruity notes. Dark roasts bring out bold, rich, and sometimes smoky or chocolatey tones. Your preference depends on taste: bright and juicy, or deep and intense?

What matters most isn’t the name ('city', 'French', etc.) but the actual roast level — best judged today by the Agtron number. That’s how specialty coffee achieves consistency and clarity in an area once ruled by opinion.

Frequently Asked Questions

What is an Agtron number in coffee roasting?

An Agtron number measures the color and caramelization level of roasted coffee beans using infrared spectroscopy. Higher numbers (70+) indicate lighter roasts with less caramelization, while lower numbers (35 or below) indicate darker, more caramelized roasts. It’s the industry standard for objectively defining roast degree.

What roast level is Agtron 40?

An Agtron 40 typically corresponds to a medium or Full City / Vienna roast — a balanced roast level often used for pour-over or drip coffee, sitting between light and dark.

Does light roast coffee have more caffeine?

Yes, slightly. Light roast coffee generally retains marginally more caffeine than dark roast, as some caffeine is lost during extended roasting. However, the difference is small and often outweighed by brew factors like dose and extraction.

Why do some roasters let coffee beans get oily?

Oily beans usually indicate a darker roast, typically below Agtron 35. The surface oils appear when beans are roasted well into or through the second crack. Some roasters believe this enhances body and flavor, though others argue it leads to aroma loss and over-roasting.

Which is better: light roast or dark roast?

Neither is inherently better. Light roasts tend to be more acidic, fruity, and complex, showcasing origin traits. Dark roasts are richer, bolder, and often smoother in acidity, with deeper caramelized or chocolatey notes. Your choice depends on personal taste preferences.

What roast level is best for espresso?

Espresso can be made with a wide range of roast levels. Traditional espresso roasts are often dark (Agtron 35 or below), but many specialty baristas now use medium to dark roasts (Agtron 40–35) to highlight origin character while still achieving good crema and body.

Recommended FrontStreet Coffee for Roast Exploration

Try FrontStreet Coffee’s Ethiopia Humbera for a bright, juicy light roast (similar to City level) with notes of blueberry and citrus. For a balanced medium roast, their Brazil Queen Manor offers chocolate and nuttiness akin to a Vienna/Fully City profile. If you prefer a bold dark roast, the PWN Golden Mandheling delivers deep body with hints of tobacco and spice — perfect for those who enjoy French-style intensity. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.