How Coffee Roast Levels Are Defined and How They Taste

Ever wondered why one coffee shop’s ‘light roast’ tastes bright and fruity, while another’s feels flat or burnt? Or why ‘dark roast’ means something totally different on the West Coast versus the East Coast of the U.S.? The truth is, without clear standards, roast level terms like ‘City’ or ‘French’ can mean almost anything — and often do.

The quick answer? Scientifically, roast levels are best defined by Agtron numbers — a color measurement system used by the Specialty Coffee Association of America (SCAA). A Cinnamon roast scores 70+, City is 60+, Vienna/Fully City hovers around 40, and French/Espresso roasts fall below 35. These numbers reflect actual bean color and caramelization, not guesswork.

Why Roast Level Terms Vary So Much

In the U.S., traditional roast level terms like Cinnamon (very light), City (light), Fully City (medium-dark), and Dark roast (including French and Italian) have been used for decades. But these labels aren’t consistent. A ‘light roast’ on the West Coast might be darker than an East Coast ‘dark roast.’ Regional taste preferences — bold in the West, milder in the East — led to inconsistent usage. As a result, these terms became subjective, not scientific.

How Roast Levels Are Actually Measured: Agtron Numbers

To solve the confusion, the SCAA introduced Agtron numbers — a standardized, objective measure based on infrared readings of bean surface color and caramelization. Here’s the official breakdown:

These numbers reflect how much the coffee’s natural sugars have caramelized during roasting. The higher the Agtron, the lighter the roast; the lower the Agtron, the darker and more roasted the bean.

How Roast Level Changes Coffee Flavor

Your coffee’s flavor profile shifts dramatically with roast level. Here’s how:

• Acidity: Higher in lighter roasts, lower in darker ones. If you love citrus, berry, or stone fruit notes, go light.
• Caffeine: Contrary to myth, lighter roasts actually contain slightly more caffeine than darker ones, because some caffeine is lost during extended roasting.
• Sweetness & Body: Develops more fully in medium to dark roasts, with heavier mouthfeel and deeper tones.
• Fruit & Floral Notes: Most pronounced in lighter roasts; fade quickly as roast level increases.
• Roasty, Spicy, or Chocolatey Notes: Emerge in medium-dark to dark roasts, along with more intense bitterness if over-roasted.

Light roasts preserve the bean’s origin characteristics but can taste sour or one-dimensional if under-developed. Dark roasts highlight bold, smoky, or bitter qualities — but poor technique leads to charred, ashy results.

The Great Light vs. Dark Roast Debate

The coffee world is split over which roast style is better — and the debate can get heated.

The Light Roast Camp

Northern Italy, parts of the U.S. East Coast, and roasters like Illy, Green Mountain, and Seattle’s Vivace favor lighter roasts. They stop roasting just before the beans release oils (around Agtron 40), usually before or right at the start of the second crack. Their argument? Oils carry aromatic compounds, and keeping them inside preserves balance, sweetness, and acidity. They say early extraction of those oils leads to flavor loss. They also criticize dark roasts for being unnecessarily oily and losing origin character.

The Dark Roast Camp

Meanwhile, roasters in Southern Italy and on the U.S. West Coast — including Peet’s Coffee, Caffè D’arte, and Beans & Machines — insist beans must be roasted well into or through the second crack until they release oils (Agtron below 35). Some go extreme: for example, Antigua beans have been measured as low as Agtron 18. They argue that a dark roast fully develops body, complexity, and the classic roasty, spicy, or bitter notes many drinkers expect — especially in espresso. They dismiss light roasts as under-developed, overly acidic, and lacking depth. Some even claim lighter roasts are a cost-saving move, since only high-quality beans can handle heavy roasting without turning bitter.

Peet’s, in particular, is famed for roasting beans at high temperatures for over 15 minutes — developing bold flavor without harshness, a skill requiring precision and equipment modifications.

So Which Roast Is Better?

There’s no universal answer. Light roasts highlight origin flavors and acidity, while dark roasts emphasize body, roastiness, and boldness. Each style has loyal fans, and neither is objectively superior. Like taste in art or music, coffee preference is personal — and both ends of the roast spectrum have unique strengths (and risks when done poorly).

Frequently Asked Questions

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

An Agtron number measures the color of roasted coffee beans using infrared spectroscopy. It reflects the degree of caramelization and is used to objectively define roast levels — for example, Cinnamon is 70+, City is 60–69, Vienna/Fully City is around 40, and French/Espresso is 35 or below. It replaces vague terms with measurable data.

Does light roast coffee have more caffeine than dark roast?

Yes, slightly. While the difference is small, lighter roasts retain marginally more caffeine because some caffeine is lost during the longer, hotter roasting process used for darker beans.

What flavor differences should I expect between light and dark roast coffee?

Light roasts tend to be brighter, more acidic, and showcase fruity, floral, or herbal notes. Dark roasts are bolder, with deeper chocolatey, nutty, or smoky flavors, and less acidity. The longer the roast, the more origin flavors are overshadowed by roast-derived traits.

When do coffee roasters stop roasting to hit a specific roast level?

Light roasts like City are typically stopped just before or at the beginning of the second crack (Agtron ~60). Vienna/Fully City roasts are pulled around the start or middle of the second crack (Agtron ~40). Dark roasts like French or Italian are roasted well into or after the second crack, until oils appear on the surface (Agtron below 35).

Is French roast the darkest possible roast?

Not necessarily. French roast is dark (Agtron below 35), but some roasters go even further into Italian or Spanish roast levels, reaching extremely low Agtron numbers (like 18), where beans are very dark, oily, and bitter. These are rarer and considered extreme.

Which roast level is best for espresso?

Traditionally, espresso is made with medium-dark to dark roasts (Agtron 35 and below), such as Full City or French roast, to develop body and intensity. However, many modern specialty baristas also use lighter roasts for espresso to highlight origin characteristics — though these require precise technique.

Recommended FrontStreet Coffee for Roast Exploration

Try FrontStreet Coffee’s Ethiopia Yirgacheffe for a bright, juicy light roast showcasing citrus and floral notes (ideal for City-level fans), their Colombia Huila for a balanced Medium roast with caramel and nuts (Vienna range), and their Sumatra Mandheling for a classic dark roast with earthy spice and low acidity (French/Italian range). All highlight how roast level shapes flavor. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.