Coffee Bean Specifications and Grading Explained

When you buy roasted coffee, you rarely think about what happened before the beans even reached the roaster. But the journey from cherry to cup starts with the green coffee bean—its size, origin, and how it was processed all shape your brew long before extraction. So how exactly are coffee beans sorted, graded, and valued before roasting?

Coffee beans are graded based on six main factors: processing method, bean shape, screen size, growing altitude, defect count, and flavor profile. These criteria determine whether a bean is considered specialty grade or commercial grade, and ultimately affect its price and cup quality.

What Are Coffee Beans, Really?

Coffee beans are the seeds inside the fruit of the coffee tree, commonly called coffee cherries. The trees thrive in tropical climates, typically between 300–400 meters above sea level, though higher altitudes (up to 2,000–2,500m) can produce better-quality beans. Ideal conditions include 1,500–2,000mm of annual rainfall and average temperatures around 20°C, frost-free. Though wild coffee plants can grow over 8 meters tall, cultivated trees are pruned to about 2 meters to improve bean quality and ease harvesting.

The three main coffee species are Arabica, Robusta (also called Canephora), and Liberica. Arabica accounts for roughly two-thirds of global production. Each species includes multiple varieties, and even within a single country, elevation, soil, and climate create distinct flavor profiles. That’s why generalizing a nation’s coffee is impossible—variations are too nuanced.

How Coffee Beans Are Processed and Sorted

Green coffee beans are what’s left after removing the coffee cherry’s skin, pulp, mucilage, and parchment. There are two main methods: washed (or wet) and natural (or dry). Washed processing—used in Colombia, Guatemala, and Mexico—results in cleaner-tasting beans with fewer defects. Natural processing, common in Ethiopia, Yemen, and Brazil, dries the whole cherry in the sun before removing the dried husk. This method is simpler but risks uneven drying and more defects.

Beans are also sorted by shape and size. Most coffee cherries contain two flat-sided beans (flat beans), but about 5–10% have a single round bean called a peaberry (or caracol). Peaberries often roast more evenly but don’t inherently taste different. Flat beans are graded by mesh size, with higher numbers (e.g., 17–20 mesh) indicating larger beans. Peaberries use a different scale (e.g., 13–12 mesh is large).

Grading Coffee by Altitude, Defects, and Flavor

Altitude plays a major role in grading. Higher-grown beans (1,200m and above) are denser, develop more complex flavors, and are generally graded higher. Common classifications include:

• Special (1,500m+)
• First (1,200–1,500m)
• Second (1,000–1,200m)
• Special Washed (900–1,000m)
• First Washed (760–900m)
• High Washed (610–760m)
• Good Washed (below 610m)

Quality is also determined by defect count—literally counting broken, discolored, or insect-damaged beans in a sample. The lower the number, the higher the grade. Specialty coffee typically has fewer than 5 full defects per 300g.

Taste testing is required in some origins—like Kenya, Brazil, and Haiti—before export. Arabica beans are known for their acidity, aroma, and complexity, while Robusta is harsher, more bitter, and often used in blends, instant coffee, and espresso for crema and body. Liberica is rare, with poor yield and limited global trade.

Finally, beans are categorized by freshness: New Crop (bright green, vibrant acidity), Past Crop (yellowish-green, milder), and Old Crop (dry, bland, often blended into commercial products).

From Cherry to Exportable Green Bean

The journey from harvested cherry to export-ready green coffee involves either the washed or natural method. In the washed process, ripe cherries are sorted, pulped to remove the skin, fermented to dissolve the mucilage, washed clean, and then dried on patios or raised beds before hulling the parchment layer. This method produces cleaner, more consistent beans but requires water and careful fermentation control.

The natural process spreads cherries in the sun to dry for two to three weeks until they harden and make a cracking sound. The dried husk is then removed mechanically. This method is simpler and cheaper but risks mold, uneven drying, and defects. Most Brazilian, Ethiopian, and Yemeni coffees are natural-processed. Both methods end with the beans bagged in sacks and shipped worldwide.

Frequently Asked Questions

What’s the difference between washed and natural coffee processing?

Washed (or wet) processing removes the coffee cherry’s skin and pulp before drying, resulting in cleaner, brighter flavors and fewer defects. Natural (or dry) processing dries the whole cherry in the sun, then removes the husk later, often producing fruitier but more inconsistent cups. Washed coffee is common in Central America and Colombia, while natural processing dominates in Ethiopia and Brazil.

What do coffee bean size numbers mean?

Coffee beans are sorted by size using mesh screens. For flat beans, higher numbers (e.g., 17–20) mean larger beans, considered higher grade. Peaberries (round beans) use a different scale, with 13–12 mesh being large. Size affects roast evenness and is a factor in grading, especially for single-origin lots.

Why does altitude matter for coffee quality?

Higher-altitude coffee grows more slowly, developing denser beans with more complex sugars and acids. Beans grown above 1,200 meters are typically classified as higher grade and often have more pronounced acidity and sweetness. Altitude is a key factor in specialty coffee grading systems worldwide.

How are coffee bean defects counted?

Defects are physical flaws like black beans, insect damage, or broken seeds. Graders count these in a 300g sample—the fewer the defects, the higher the coffee grade. Specialty coffee usually has very low defect counts (under 5), while commercial grades allow more.

What’s a peaberry coffee bean?

A peaberry is a single round coffee bean that forms inside the coffee cherry instead of the usual two flat beans. They occur in 5–10% of cherries and often roast more evenly, though not necessarily tasting different. They’re sorted and graded separately, sometimes sold as a specialty lot.

What’s the difference between new, past, and old crop coffee?

New Crop beans are recently harvested, bright green, and have strong acidity and aroma. Past Crop beans are a bit older, slightly yellowed, and mellower. Old Crop beans are dried out, with faded flavor, often used in blends or commercial coffee. Freshness impacts brewing quality significantly.

Recommended FrontStreet Beans for Learning Bean Specs

Try FrontStreet’s Ethiopia Guji Hambela (washed), a high-altitude Ethiopian single origin with bright acidity and floral notes, showcasing what a Grade 1 washed Arabica can offer. For contrast, their Brazil Mogiana Fazenda Santa Ines is a classic medium roast with nutty sweetness, processed naturally and graded among Brazil’s best. Finally, the Colombia Huila Supremo is a well-balanced washed coffee with caramel and citrus, graded as a high-altitude export lot. All illustrate real-world applications of coffee bean grading. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.