How Specialty Coffee Green Beans Are Graded

When you buy specialty coffee, have you ever wondered how those green beans were sorted before roasting? Whether you’re a home roaster or just curious about quality, understanding how coffee beans are graded helps you make better choices. Grading isn’t just about looks—it impacts roast consistency, flavor potential, and price.

In short, green coffee beans are graded primarily by two methods: bean size (using sieve numbers) and growing altitude (with defined elevation bands). Size grades range from small (8/64 inch sieve) to very large (like SC-19), while altitude grades go from lowland (under 2000 feet) to high-altitude SHB (1600–1700 meters). Each system serves a purpose: size for roast evenness, altitude for cup quality.

Grading by Sieve Size: What the Numbers Mean

Coffee beans are often sorted by physical size using round metal sieves with holes measured in 1/64-inch increments. The number refers to the sieve mesh—e.g., a "14" sieve has holes of 14/64 inch. A bean labeled "19" means it can pass through a 19/64-inch sieve. The notation "19+" means the bean passes through a 19/64-inch sieve or larger.

Flat beans (the common bean shape) typically range from sieve 12 to 29, while peaberries (smaller, rounded beans) usually fall between 8 and 13. In this system, the higher the number, the larger the bean. For example, an SC-19 bean is considered quite large. This sorting helps ensure uniformity for even roasting.

The international standard includes mesh sizes from 9 to 22, with the number representing 1/64 of an inch. So, a "14" sieve has an opening of 14/64 inch. Sieve sizes help roasters achieve consistency, especially in commercial lots.

Grading by Altitude: Elevation Impacts Quality

Coffee grown at higher altitudes tends to develop slower, producing denser beans with more complex flavors. Many coffee-growing countries grade beans by the altitude of the farm, using specific abbreviations and height bands.

Generally, the higher the elevation (e.g., SHB or Strictly High Grown), the denser and more flavorful the bean. These grades also often justify higher prices due to lower yields and increased shipping costs.

Country-Specific Grading Standards

Different coffee-exporting nations have their own detailed grading rules. Here’s how some major origins classify beans:

Africa: Kenya & Ethiopia

Kenya uses screen sizes (e.g., AA = screen 17–18, AB = screen 15–16) and designations like PB (peaberry), AA Plus, and AA Plus-Plus. Defect counts also factor in.

Ethiopia grades mostly by defect count per 300g sample: Grade 1 (0–3 defects), Grade 2 (4–12), up to Grade 8 (over 340 defects = substandard).

South America: Colombia & Brazil

Colombia has Supremo (screen >17), Excelso (screen 15–16.5), UGQ (Usual Good Quality, screen 12–14), and special types like Maragogype (large bean variety).

Brazil grades mostly by defect count (e.g., Type 2 allows 4–12 defects in New York and Le Havre standards, Type 3 allows 12–13, etc.). Screens may also apply.

Central America: Guatemala, El Salvador

Guatemala uses altitude-based terms: Good Washed (700m), Extra Good Washed (700–850m), Prime Washed (850–1000m), up to Strictly Hard Bean (SHB, 1600–1700m).

El Salvador separates washed (e.g., SHG for >1200m) and natural process beans (e.g., Superior, Corriente).

Hawaii, Jamaica, Indonesia

Hawaii Kona has grades like Extra Fancy (screen 19, ≤10 defects), Fancy (screen 18, ≤16 defects), Prime (no size rule, ≤25 defects), and Caracoli No.1 (screen 10, ≤20 defects).

Jamaica Blue Mountain includes High Mountain Supreme and graded screens (Grade I = screen 18, Grade II = 17, Grade III = 16).

Indonesia grades mostly by defects in 300g samples: Grade 1 (11 defects), Grade 2 (12–25), up to Grade 6 (151–225 defects).

Why Grading Matters

Grading ensures that green coffee meets certain physical and qualitative standards. Size grading improves roast consistency, while altitude grading often correlates with density and cup complexity. Together, these systems help roasters select beans that match their profiles and customers’ expectations. They also affect pricing and trade, especially in the specialty market.

Frequently Asked Questions

What does the number on a coffee sieve mean?

The number on a coffee sieve refers to the size of the holes in 1/64-inch units. For example, a “14” sieve has holes that are 14/64 of an inch in diameter, and a bean labeled “19” can pass through a 19/64-inch sieve. A higher number means a larger bean.

Why are higher altitude coffee beans considered better?

Higher altitude typically means slower bean development, resulting in denser beans with more complex flavors and higher acidity. Grades like SHB (Strictly High Grown) or SHG (Strictly High Grown) indicate beans grown at 1600–1700 meters or above, often associated with premium quality.

What is a peaberry and how is it graded?

A peaberry is a rare, smaller coffee bean that forms when only one round seed develops inside the coffee cherry instead of two flat beans. In countries like Kenya, peaberries are graded separately (e.g., PB) and often roasted as a distinct product with unique flavor profiles.

How do defect counts affect coffee grading?

Defect counts refer to the number of flawed or damaged beans in a 300g sample. Lower defect counts (e.g., 0–3 in Ethiopia’s Grade 1) indicate higher quality. Higher defect counts can downgrade the coffee to lower commercial or substandard grades, affecting taste and value.

Does coffee bean size affect roasting?

Yes. Uniform bean size helps ensure even roasting. A mix of very large and very small beans can lead to uneven development, with some beans under-roasted and others over-roasted. That’s why commercial and specialty roasters often sort beans by size.

Recommended FrontStreet Beans for Grading Insight

Try FrontStreet’s Ethiopia Guji Natural for bright, juicy complexity from high-altitude beans (likely SHG-grade equivalents), and their Colombia Huila Supremo for a classic Supremo-grade profile with balanced sweetness and body. For size comparison, their Kenya AB offers a textbook example of mid-range sieve-graded beans with winey acidity. All showcase how grading impacts cup profile. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.