How Coffee Beans Are Graded: Size and Altitude Standards

Ever wondered why some single-origin coffees command much higher prices or why certain beans roast differently? The secret lies in how those green coffee beans were sorted and classified before they reached your roaster. Grading isn’t just a formality — it affects everything from brewing performance to cup quality.

In short, coffee beans are graded primarily by two methods: screen size (mesh number) and growing altitude. Screen size uses numbers like 15, 18, or 19 to sort beans by diameter, while altitude grades range from as low as 2000 feet to over 4500 feet, with higher elevations generally indicating better quality.

What Is Coffee Bean Grading?

Coffee bean grading is the process of categorizing green coffee based on physical characteristics and growing conditions. The main goals are to ensure uniformity for roasting and to signal bean quality to buyers. Grading helps roasters predict how beans will behave during roasting and brewing, and it plays a major role in determining market price.

Grading by Screen Size (Mesh Number)

One of the most common methods to grade green coffee is by using perforated metal screens with specific hole sizes, measured in 1/64th of an inch. These are referred to as "sieve" or "screen" numbers — for example, a number 18 screen has holes 18/64 of an inch in diameter.

Beans are sorted by passing through these screens. The larger the screen number, the larger the bean. Here’s how the sizing typically breaks down:

• Smaller beans: Screens 8 to 12 (e.g., screen 8–10 = very small; screen 12 = medium-small)
• Medium to large beans: Screens 13 to 18 (e.g., screen 15–16 = common commercial grade; screen 17–18 = premium specialty grade)
• Larger beans: Screens 19 to 29 (e.g., screen 19 = large; screen 20+ = extra-large or specialty grade)

Special note: Peaberry beans (small, round beans formed when one seed develops instead of two) are usually smaller than flat beans and often fall in lower screen ranges like 8–13. For example, SC-19 refers to a screen 19 grade bean. Larger screen sizes such as 19+ mean the beans can pass through a 19/64” screen or larger.

The actual measurement is based on the diameter of the bean: a screen number “X” means the bean can pass through a mesh with holes sized X/64 inches. A designation like “19+” indicates the bean is larger than 19/64 inches.

How Size Affects Roasting and Flavor

Larger beans often roast more evenly due to consistent mass distribution, although this also depends on density and processing. Many specialty roasters prefer larger beans of uniform size for even development during roasting. That said, smaller beans like peaberries can have concentrated flavors but may require separate roasting profiles.

Grading by Altitude

The other primary grading method is based on the altitude where the coffee is grown. Higher altitudes typically produce slower maturation, denser beans, and more complex flavors. Most exporting countries classify beans into different grades based on elevation ranges.

Here’s a general global altitude grading structure (though each country has variations):

Higher altitude grades like SHB (4500+ feet) are associated with denser beans, more pronounced acidity, and complex flavour profiles — all highly valued in specialty coffee.

Country-Specific Grading Standards

Different coffee-growing countries have their own detailed grading systems, often reflecting local growing conditions, bean types, and market traditions. Here are a few notable examples:

Africa: Kenya

• PB: Peaberry beans
• AA Plus-Plus, AA Plus, AA: Screen 17–18 (highest grades)
• AB: Screen 15–16
• C, E: Lower grades

Ethiopia

• Grading is defect-based. For every 300g sample:
• Grade 1: 0–3 defects
• Grade 2: 4–12 defects
• … up to Grade 8: over 340 defects = substandard

Colombia

• Supremo: Screen >17 (large beans)
• Excelso: Screen 15–16.5
• UGQ (Usual Good Quality): Screen 12–14
• Maragogype: “Elephant bean” (very large bean variety)

Brazil

• Uses defect counts (e.g., Type 2 allows 8 defects per 300g; Type 3 allows 12, etc.)
• Grades range from 2 to 6, with lower numbers indicating fewer defects

Guatemala

• Good Washed: 700m (GW)
• Extra Good Washed: 700–850m (EGW)
• Prime Washed: 850–1000m (PW)
• Extra Prime Washed: 1000–1200m (EPW)
• Semi Hard Bean (SH): 1200–1350m
• Hard Bean (HB): 1350–1500m
• Fancy Hard Bean (FHB): 1500–1600m
• Strictly Hard Bean (SHB): 1600–1700m (highest grade)

El Salvador

• Central Standard (CS): 500–900m
• High Grow (HG): 900–1200m
• Strictly High Grown (SHG): above 1200m

Hawaii (Kona)

• Kona Extra Fancy: Screen 19, max 10 defects
• Kona Fancy: Screen 18, max 16 defects
• Kona Prime: no size rule, max 25 defects
• Kona Caracoli No.1: Screen 10, max 20 defects

Jamaica

• Blue Mountain grades include:
• Grade I: Screen 18
• Grade II: Screen 17
• Grade III: Screen 16
• Peaberry: also graded separately

Indonesia

• Grading is defect-based using a 300g sample:
• Grade 1: 11 defects
• Grade 2: 12–25 defects
• … up to Grade 6: 151–225 defects

Why Grading Matters

Grading affects pricing, roast profiles, and flavor outcomes. Higher-graded beans (by size or altitude) are often more valuable due to their uniformity, density, and complexity. Roasters use grade data to select beans suited to their profiles, whether they’re aiming for bright, high-altitude Ethiopian lots or balanced Brazilian blends.

Grading also ensures basic quality control — such as screening out defective beans — which is critical for specialty coffee standards where defects significantly impact cup quality.

Recommended FrontStreet Coffee Beans for Grading Insights

Explore FrontStreet Coffee’s Ethiopia Guji Humbera, a Strictly High Grown (SHG) lot with vibrant fruit and floral notes, showcasing high-altitude specialty grade traits. For screen size comparison, try their Colombia Excelso — a balanced, medium-bright cup from screened 15–16.5 beans. Also look at Guatemala Antigua Prime Washed, a classic SHB-grade coffee with chocolatey depth and a structured profile. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.