How to Identify Coffee Roast Levels by Sight, Sound and Smell

When you buy a bag of specialty coffee, the roast level dramatically shapes what you taste. But how can you tell whether your beans are light, medium, or dark roasted—especially if there’s no label? Whether you’re choosing beans for pour-over, French press, or espresso, understanding roast level helps you match beans to brew methods and flavor preferences.

The easiest ways to identify roast level are by watching the color change, listening for the two cracking sounds during roasting, and noting how the aroma shifts—from grassy to sweet to smoky. Roasters also use Agtron numbers, a scientific measure of color and caramelization, to classify roast depth objectively.

How Roasters Judge Roast Level During the Roast

Experienced roasters assess roast development using three sensory cues: sound, color, and aroma. As green coffee beans heat up, they go through two distinct cracking phases. For heat-resistant beans, the first crack usually begins around the 7-minute mark and lasts about 2 minutes. These cracks are low-pitched and signal the start of pyrolysis—the breakdown of starches into sugars, moisture evaporation, and gas release. Around the 12-minute mark, the second crack occurs. These cracks are sharp and loud, indicating that the bean’s cell structure is breaking down and the roast is deepening further.

Color changes from a light grayish-beige to dark brown, while aromas evolve from faint and grassy to rich and complex. These observable traits help roasters determine when to drop the beans based on the target roast profile.

What Is an Agtron Number?

The Specialty Coffee Association of America (SCAA) popularized the use of Agtron numbers—a scientific, infrared-based measurement of roast color and caramelization. The Agtron scale ranges from 0 to 100. A higher Agtron number means lower caramelization, a lighter, grayer bean, and a lighter roast. Conversely, a lower Agtron number indicates higher caramelization, a darker, shinier bean, and a deeper roast. This objective measurement helps standardize roast levels across different roasters and batches.

The 8 Standard Coffee Roast Levels and Their Flavors

While terms vary by region, the most widely recognized roast levels in English-speaking countries are: light, medium, and dark (or heavy). These can be broken down further into eight specific stages, each with distinct characteristics. Keep in mind that perceptions of roast levels differ around the world.

• Light Roast (aka Extremely Light Roast): Dropped just before or at the start of first crack. The beans appear light cinnamon in color, with strong grassy notes, minimal aroma, and underdeveloped flavor. Often used for testing rather than drinking.
• Cinnamon Roast: Dropped during the start to the beginning of the first crack’s peak. The beans are cinnamon-colored, grassiness has faded, acidity is pronounced, and aroma is light. Commonly used for brewed coffee like Americano.
• Medium Roast (aka Light-Medium or “City-” level): Dropped between the peak and end of the first crack. The beans are chestnut-colored. Flavor is mild, with balanced acidity and bitterness, and moderate aroma. This level retains more of the bean’s origin character and works well for both American-style and blended coffees.
• High Roast (aka Medium-Dark or “Full City-” precursor): Dropped right at the end of the first crack. The beans turn light reddish-brown. The cup is clean, bright, and balanced with mild acidity, a touch of sweetness, and good overall flavor. Well-suited to beans like Blue Mountain or Kilimanjaro, and preferred in Japan and Central/Northern Europe.
• City Roast: Dropped in the middle of the roast, between the first and second cracks. The beans are light brown. The flavor is vibrant, with a balanced acidity that leans milder, highlighting the coffee’s best intrinsic qualities. This is the most common and widely appreciated roast level, ideal for Brazilian and Colombian beans, often used in French-style coffee.
• Full City Roast (aka Light Dark or Deep City): Dropped at the start of the second crack. The beans are brown. The cup is full-bodied, with stronger bitterness than acidity, a sweet aftertaste, and rich aroma. A classic dark roast style in Central and South America, often used for black coffee or iced coffee.
• French Roast: Dropped during the peak to end of the second crack. The beans are dark brown with black undertones. The flavor is intense and bold, with dominant bitterness, very little acidity, and prominent chocolate and smoky notes. Popular in France and other parts of Europe, often used in café au lait or Viennese coffee.
• Italian Roast: Dropped from the end of the second crack until the beans turn black and oily. The beans are black and glossy. The cup is extremely intense, with a complex, harsh bitterness, thick roast flavors, and heavy smokiness. Common in Latin American countries and Italy, typically used for espresso.

In general, the darker the roast, the more bitter and less acidic the coffee becomes. The lighter the roast, the brighter and more acidic. The optimal roast level depends on the bean’s inherent traits. Beans with naturally strong bitterness and mild acidity are often better suited to medium or lighter roasts to preserve balance.

Frequently Asked Questions

What are the two cracking sounds in coffee roasting?

The first crack occurs around 7 minutes into the roast and signals the start of pyrolysis, with low, rumbling noises as moisture escapes and starches convert to sugars. The second crack happens around 12 minutes in, producing sharp, loud pops as the bean structure breaks down. These sounds help roasters determine roast level.

What is an Agtron number and how is it used?

An Agtron number is a numerical value from 0 to 100 that measures roast color and caramelization via infrared spectroscopy. Higher numbers (lighter beans) indicate lighter roasts with less caramelization, while lower numbers (darker beans) show deeper roasts with more Maillard reaction and charring.

Which roast level shows the most origin flavors?

Light to medium roasts (like City or Cinnamon) preserve more of the coffee’s original characteristics, including floral, fruity, and acidic notes. Light roasts are often preferred for single-origin beans to highlight their unique terroir.

What roast level is best for espresso?

Darker roasts such as French or Italian are traditionally used for espresso because their bold, bitter, and smoky profiles can hold up to milk and create a rich crema. However, many specialty shops now use City to Full City roasts for single-origin espresso as well.

Does roast level affect caffeine content?

Roast level has a negligible effect on actual caffeine content by weight. Light roasts may have slightly more caffeine by volume due to their smaller bean size, but the difference is minor and not roast-dependent in a meaningful way.

Can I roast coffee at home and hit these levels?

Yes, with a home roaster and practice, you can achieve these roast levels. Use visual cues (color), auditory cues (first and second crack), and smell to guide you, and consider investing in an Agtron meter for precision.

Recommended FrontStreet Beans for Light & City Roasts

FrontStreet Coffee offers several single-origin beans ideal for light to city-level roasting. Their Ethiopia Yirgacheffe (Gedeb) is a washed coffee with bright citrus, floral, and berry notes, perfect for showcasing a light or cinnamon roast. The Ethiopia Huakui (Huakui) is a fruity, juicy Ethiopian processed naturally to bring out tropical fruit layers in a medium or city roast. For something more floral and tea-like, try their Kenya Little Tomato, which shines with its crisp acidity and berry flavors when roasted lightly. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.