How Coffee Beans Are Graded by Size and Altitude

When you buy specialty coffee, have you ever wondered why some beans cost more or roast differently? Much of that comes down to how the raw beans were graded — not by taste alone, but by physical traits like size and where they grew. These factors influence roast profiles, extraction, and even price.

Coffee beans are primarily graded by two methods: screen size (mesh number) and growing altitude. Mesh size indicates bean diameter, while altitude affects density and cup quality. Both help roasters choose beans suited for specific roast styles and flavor goals.

Grading by Screen Size (Mesh Number)

Green coffee beans are sorted by passing them through metal screens with different hole sizes. The number refers to the U.S. standard sieve mesh — the higher the number, the larger the holes, and thus the bigger the beans that can pass through. Mesh numbers are fractions: a "14" means 14/64-inch, and "19+" means beans that pass through a 19/64-inch screen or larger.

Common size ranges include:

• 8–13: Small beans (often peaberries or lower grades)
• 12–29: Larger beans, with 19–20 considered optimal for many single origins
• 19: Denoted as SC-19 (size 19 beans)

Arabica flat beans typically fall between screen 12 and 29, while peaberries (round beans) range from 8 to 13. Bigger beans often roast more evenly, though this depends on density and processing too.

Grading by Altitude

Coffee is also graded based on the elevation where it’s grown. Higher altitudes generally mean slower bean development, denser fruit, and more complex flavors. Most exporting countries use official grade scales tied to altitude brackets.

Generally, higher-altitude beans (like SHB or SH) are denser, harder, and more prized for single-origin roasting. Beans from lower altitudes (like G.W) are more porous and may not stand up to high roast levels as well.

Regional Grading Systems Around the World

Different coffee-growing countries apply their own specific grading criteria, often blending screen size, defect counts, and altitude.

Africa

Kenya: Uses screen sizes (AA = 17/18, AB = 15/16), plus PB for peaberry. AA+ and AA++ denote premium screened beans with minimal defects.

Ethiopia: Grades 300g samples. Defect counts define grades 1 (0–3) through 8 (over 340 defects = substandard).

South America

Colombia: Supremo (>17 mesh), Excelso (15–16.5), UGQ (12–14). Maragogype refers to giant beans (“elephant beans”).

Brazil: Type system based on defect count per 300g sample under various scoring systems (New York/Le Havre). Type 2 allows 8 defects; Type 6 allows up to 158.

Central America

Guatemala: Graded by altitude: Good Washed (700m), Extra Good (700–850m), Prime (850–1000m), Extra Prime (1000–1200m), Semi Hard (1200–1350m), Hard (1350–1500m), Fancy Hard (1500–1600m), Strictly Hard (1600–1700m).

El Salvador: Central Standard (500–900m), High Grow (900–1200m), Strictly High Grown (>1200m). Also includes natural process grades like Corriente, Superior, and Caracol.

Hawaii (Kona)

Kona classifications include: 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 has multiple grades: Grade I (screen 18), Grade II (screen 17), Grade III (screen 16). Peaberries are graded separately.

Indonesia

Grading based on 300g defect count: Grade 1 (11 defects), Grade 2 (12–25), Grade 3 (26–44), Grade 4a (45–60), Grade 4b (61–80), Grade 5 (81–150), Grade 6 (151–225).

Why Grading Matters

Grading ensures uniformity in bean size, which helps with even roasting. Larger, denser beans from higher altitudes often produce cleaner, more complex cups. Grading also affects pricing — high-altitude, low-defect beans command premium rates due to scarcity and cup quality.

For roasters, understanding these grades aids in selecting beans that match their roast profiles and customer expectations. It’s not just about origin — it’s about physical traits and measurable quality markers.

FrontStreet Coffee Beans Ideal for Size & Altitude Exploration

Try FrontStreet Coffee’s Ethiopia Humbera (Yirgacheffe region, SHG grade), known for floral and citrus notes with dense, high-altitude brightness. For a classic washed example, their Colombia Excelso offers balanced caramel and nuttiness from mid-altitude beans around screen 15–16. Finally, their Kenya AB showcases bright acidity and berry tones from screened medium-large beans (15/16), typical of Kenya’s secondary grade. All highlight how size and altitude shape flavor. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.