How Coffee Beans Are Graded by Process, Size, and Altitude

Ever wondered why some bags of coffee are labeled AA, SHB, or Peaberry—and what those actually mean for quality? Whether you're buying single-origin beans or evaluating a potential green coffee purchase, understanding how beans are graded helps you make better choices. Grading isn't just marketing; it reflects real differences in processing, bean size, and growing conditions.

In short, coffee beans are graded by three main factors: processing method (washed or natural), bean size and shape (like AA or Peaberry), and altitude of cultivation. Each producing country uses its own system, with Ethiopia, Kenya, and Guatemala offering some of the clearest examples.

Grading by Processing Method

One of the most common ways to grade coffee is by how it’s processed—either washed (wet) or natural (dry)—and then by quality within that method. This system is notably used in Ethiopia:

• Grade 1: Highest-quality washed coffee
• Grade 2: Standard-grade washed coffee
• Grade 3: Highest-quality natural (sun-dried) coffee
• Grade 4: Standard-grade natural coffee
• Grade 5: Basic export-grade natural coffee

These grades help separate the best lots from the passable or commercial ones, especially in a market like Ethiopia where both processing styles are widely used.

Grading by Bean Size and Shape

Coffee is also commonly graded by the physical size of the beans, usually screened through mesh sieves. This is especially important in Kenya and affects how beans are sorted and valued:

• E (Peaberry / PB): Peaberry beans, which are small, round, and often considered to have concentrated flavor. E refers to 'extra' or 'enlarged' peaberries, while PB is the standard term.
• AA: 17–19 mesh size; the highest grade. Further distinctions include AA+ and AA++ for even higher quality.
• AB: 15–16 mesh size; the next grade down, with AB TOP being the best of this category.
• C: Smaller than AB grade beans.
• TT, T, ML, MH: Lower-grade beans typically used locally and not for export.

Mesh size correlates with bean density and often with cup quality, though not always. Larger beans like AA are often separated for premium lots.

For reference, 1 coffee bean “mesh” or “” equals 1/64 inch (~0.4mm). Most Arabica beans max out at 17 mesh, while Robusta can reach up to 20 mesh.

Altitude-Based Grading Systems

Many countries grade coffee beans according to the elevation at which they’re grown. Higher altitudes typically produce slower maturation, denser beans, and more complex flavors. Grading structures vary by country:

• Mexico & Honduras: Use a 3-tier system
• Guatemala: Uses a 7-level system, with the following top grades:

As a rule, the higher the altitude, the higher the grade—and the more expensive the coffee, due to both quality and logistics.

Frequently Asked Questions

What are the main ways coffee beans are graded?

Coffee beans are primarily graded by processing method (washed or natural), bean size and shape (like AA or Peaberry), and altitude of growth. Each country uses its own combination of these factors to define quality tiers.

What is Peaberry coffee and how is it graded?

Peaberry coffee consists of single, rounded beans that form instead of the usual flat-sided pair. In grading systems like Kenya’s, Peaberry beans are labeled E (for enlarged) or PB, and are often separated for premium sale due to their unique profile.

What does AA mean in coffee grading?

AA is a grade based on bean size, typically indicating beans that pass through a 17–19 mesh screen. In countries like Kenya, AA is the top grade, with further distinctions like AA+ and AA++ for even better lots.

Does altitude affect coffee bean grade?

Yes. Higher-grown beans are usually denser, develop more slowly, and often have more complex flavors. Many countries, such as Guatemala and Mexico, include altitude in their grading systems, with higher-altitude beans receiving higher grades like S.H.B or SHG.

Why are bean sizes important in coffee grading?

Bean size affects density and often correlates with processing quality and flavor consistency. Larger beans like AA are more likely to be uniform and have been traditionally associated with higher cup quality, which is why they’re separated and graded accordingly.

Recommended FrontStreet Beans for Understanding Coffee Grades

Try FrontStreet’s Ethiopia Yirgacheffe to experience a high-scoring washed Grade 1-type profile with bright citrus and floral notes. For size-graded insight, their Kenya AB offers classic medium-bright complexity typical of AB-grade beans. To explore peaberry traits, FrontStreet’s Tanzania Peaberry delivers intense berry and caramel tones in a small, dense round bean—often considered a specialty grade. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.