How Coffee Beans Are Graded by Size and Altitude

When you buy specialty coffee, have you ever wondered why some beans cost more or why certain origins are known for specific cup profiles? Much of that comes down to how the green coffee is graded—by size, density, and where it’s grown. These factors influence not just appearance, but also roast behavior, flavor development, and market value.

In short, coffee beans are graded primarily by two factors: physical screen size (measured in numbers like 15, 17, or 19) and growing altitude (ranging from under 2000 feet to over 4500 feet). Larger beans and those grown at higher elevations typically command premium grades and prices.

How Coffee Beans Are Sized: The Screen Number System

Coffee beans are sorted by physical size using mesh screens with holes measured in 1/64th of an inch. The number refers to the screen’s mesh size—the larger the number, the larger the hole, and thus the larger the beans that can pass through. For example, a "19" means the bean passed through a 19/64-inch screen. A designation like SC-19 refers to a 19-size bean.

Green coffee beans are typically categorized by these screen sizes:

• 8 to 13: Small beans (usually peaberries)
• 12 to 29: Larger beans (common for most commercial and specialty grades)
• The higher the number, the larger the bean—e.g., a 19-size bean is bigger than a 15.

Flat beans (the norm) usually measure between 12 and 29, while peaberries (smaller, rounded beans) range from 8 to 13. The size affects roast uniformity and is a key factor in grading.

Altitude-Based Grading: Why Elevation Matters

Coffee is also graded by the altitude at which it’s grown. Higher altitudes generally produce slower maturation, denser beans, and more complex flavors. Most exporting countries use altitude to define quality tiers, though the exact metrics vary by region.

Here’s a general global altitude grading scale:

• S.H.B (Strictly High Grown / Strictly Hard Bean): 4,500+ feet (1,370+ meters)
• H.B (High Grown / Hard Bean): 4,000–4,500 feet (1,220–1,370 meters)
• S.H (Semi High Grown): 3,500–4,000 feet (1,070–1,220 meters)
• E.P.W (European Preparation Washed): 3,000–3,500 feet (910–1,070 meters)
• P.W (Washed): 2,500–3,000 feet (760–910 meters)
• E.G.W (Extra Good Washed): 2,000–2,500 feet (610–760 meters)
• G.W (Good Washed): Below 2,000 feet (under 610 meters)

Higher-elevation beans are more sought-after due to their density and potential for brighter acidity and cleaner cup profiles. They also often incur higher shipping costs, increasing their price.

Country-Specific Grading Standards

Different coffee-growing countries have their own detailed grading rules. These include assessments of defect counts, bean size distribution, processing type, and more. Here are a few examples:

Africa

Kenya: Uses screen sizes 15–18 (AA = 17/18, AB = 15/16), and grades peaberries as PB. AA+ and AA++ denote top lots with minimal defects.

Ethiopia: Grades based on defects per 300g of green coffee. Grade 1 allows 0–3 defects; Grade 8 or higher is considered substandard.

South America

Colombia: Supremo (screen >17), Excelso (15–16.5), UGQ (Usual Good Quality, 12–14).

Brazil: Graded by defect count (e.g., Type 2 allows 8 defects, Type 3 allows 12–13, etc.), with additional designations used in New York and Le Havre markets.

Central America

Guatemala: Altitude-based grades include Good Washed (700m), Prime Washed (850–1000m), SHB (1600–1700m), with categories like Semi Hard Bean (1200–1350m) and Strictly Hard Bean (1600–1700m).

El Salvador: Washed grades include Central Standard (500–900m), High Grow (900–1200m), and Strictly High Grown (above 1200m).

Other Origins

Hawaii (Kona): Kona Extra Fancy (screen 19, ≤10 defects), Kona Fancy (screen 18, ≤16 defects), Kona Prime (no size limit, ≤25 defects).

Jamaica: Blue Mountain grades include Grade I (screen 18), Grade II (17), Grade III (16).

Indonesia: Grading based on defects in 300g samples—Grade 1 allows 11 defects, Grade 2 allows 12–25, up to Grade 6 (151–225 defects).

Sieve Size and Measurements

The screen sizes correspond to actual mesh openings. The number is a fraction: the size number over 64 inches. For example, a "14" screen means 14/64-inch holes. A designation like 19+ means beans that pass through a 19/64-inch screen or larger. Sieve passing rate and actual screen measurements ensure uniformity in bean size, which is critical for even roasting.

Why Grading Matters

Grading ensures consistency, predicts roast behavior, and helps buyers assess quality and value. Uniform size improves roasting consistency, while altitude and defect counts indicate potential cup quality. Exporters, importers, and roasters use these grades to set pricing, manage expectations, and maintain specialty standards.

Frequently Asked Questions

What does the number on coffee beans (like 15 or 19) mean?

The number refers to the screen size the beans passed through, measured in 1/64th of an inch. For example, “19” means the beans passed through a 19/64-inch mesh screen. Larger numbers indicate bigger beans, which often roast more evenly and are associated with higher quality.

Why are higher-altitude coffee beans considered better?

Beans grown at higher altitudes (typically above 1,200m or 4,000ft) tend to develop more slowly, leading to greater density and more complex flavors. These beans are often graded as Strictly Hard Bean (SHB) or similar premium classes and are prized for their brightness and balance.

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. Peaberries often roast differently and are graded separately, such as Kenya PB or classified under size 8–13. They’re sometimes considered to have more concentrated flavor.

How do defect counts affect coffee grading?

Defects—such as broken, black, or insect-damaged beans—are counted per 300g sample. The fewer the defects, the higher the grade. For example, Ethiopia’s Grade 1 allows 0–3 defects, while Grade 8 or higher is substandard. Specialty coffee typically requires very low defect counts.

Do all countries use the same coffee grading system?

No. Each coffee-producing country has its own grading standards, though many consider factors like bean size, altitude, and defect count. For example, Kenya uses AA and AB screen sizes, Colombia uses Supremo and Excelso, and Brazil grades mostly by defect numbers.

What is a screen size and how is it measured?

A screen size is the mesh number (like 15 or 19) that indicates the maximum size of the holes in inches (as a fraction of 64). A 19 screen has 19/64-inch holes. “19+” means beans that are 19/64-inch or larger. This sizing ensures beans are uniform for optimal roasting.

Recommended FrontStreet Beans for Size & Altitude Lovers

Explore FrontStreet Coffee’s Ethiopia Guji Humbera, a high-altitude lot (1,900–2,100m) with juicy blueberry and floral notes, showcasing the complexity of Strictly High Grown beans. Pair it with Colombia Huila Supremo—bright, balanced, and grown at 1,600–1,750m, falling into the Supremo grade with bold citrus and caramel. For something different, try Kenya AB, sourced from the 1,500–2,000m range, offering winey acidity and blackcurrant tones. All three highlight how elevation and sizing shape your cup. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.