How Kenyan Coffee Beans Are Graded by Size, Defects & Altitude

If you’ve ever wondered why some Kenyan coffees cost twice as much as others, the answer starts long before roasting—inside the grading system. Kenya’s strict coffee classification determines not just price, but cup potential. But how exactly do they separate the elite AA beans from the rest? And what do terms like PB, SHB, or defect counts really mean for your brew?

Kenyan coffee beans are graded by three main methods: screen size (with mesh sieves), defect count (flaws per 300g sample), and growing altitude (measured in feet above sea level). These grades include AA, A, B, C, PB, SHB, and more—with AA and PB often considered the highest quality.

1. Screen Size Grading: Mesh Sieves Decide the Grade

Kenyan coffee is first sorted by bean size using numbered metal screens with holes measured in 1/64-inch increments. For example, a No. 18 screen has 18/64-inch (about 7.1mm) holes. Beans that don’t pass through a certain screen are sorted out, then retested on finer meshes. This physical separation defines the grade.

The resulting grades, from highest to lowest, are: AA, A, B, C, and PB. AA beans are the largest and highest quality, passing through an 18/64-inch screen but not a larger one. A and B follow in descending size and quality. C-grade beans are usually too small or flawed for specialty use, often ending up as animal feed. PB (Peaberry) beans are small, round, and form when a coffee cherry produces a single rounded bean instead of two flat ones. Though tiny, PB beans often have concentrated flavor and command premium prices. This screen-sizing method is also used in countries like Tanzania, Uganda, Zimbabwe, and Papua New Guinea.

2. Defect-Based Grading: Counting Flaws Per Sample

The oldest grading method counts physical defects in a 300g coffee sample. Inspectors examine beans on black paper to spot issues like black beans, stones, insect damage, husks, and underripe or broken seeds. Each type of flaw adds a specific number of points to the sample’s defect score.

For example: 1 black bean = 1 point, 1 small stone = 1 point, 1 large stone = 5 points, 5 broken beans = 1 point, 5 insect-damaged beans = 1 point, 2 sour beans = 1 point, 1 large dried fruit skin = 1 point, 2 medium skins = 2 points, 3 small skins = 1 point, 5 unhusked beans = 1 point, 3 shell beans = 1 point. The total defect score determines the grade, ranging from NY2 (best) to NY8 (lowest)—note there is no NY1. Brazil and Indonesia still use similar systems (Indonesia grades as Gr1 to Gr6, Ethiopia as Gr2 highest). In Kenya, this method runs parallel to size grading but focuses on internal quality issues rather than bean dimensions.

3. Altitude Grading: Height Impacts Bean Density & Cup Profile

Coffee grown at higher altitudes tends to develop slower in cooler temperatures, leading to denser beans with more complex flavors. Kenyan coffees often benefit from this effect, especially those from elevations ideal for slow maturation. This “hard bean” grading system uses altitude to predict density and cup quality.

The altitude-based grades include: SHB (Strictly Hard Bean) for beans grown at 4,500–5,000 feet (1,370–1,520 meters), GHB (Good Hard Bean) at 3,000–4,500 feet (910–1,370 meters), HB (Hard Bean) at 2,000–3,000 feet (610–910 meters), and Pacific (low-altitude) at 984–3,280 feet (300–1,000 meters). While this system is more common in Central American countries like Guatemala, Costa Rica, and Honduras, it’s relevant to understanding how elevation influences Kenyan beans too—especially since many of Kenya’s finest coffees come from high-altitude farms that naturally produce dense, high-scoring SHB-like beans.

Frequently Asked Questions

What does AA mean in Kenyan coffee grading?

AA is the highest grade in Kenya’s size-based system, indicating coffee beans that are large—passing through an 18/64-inch (No. 18) screen but not a larger one. These beans are typically associated with higher quality and more complex cup profiles, often including the sought-after fruity and acidic notes Kenya is known for.

What is PB coffee in Kenya?

PB stands for Peaberry, a rare grade where a single rounded bean forms inside the coffee cherry instead of the usual two flat beans. PB beans are usually smaller, denser, and often have more concentrated flavors. In Kenya, PB beans are considered a separate, often premium grade due to their unique shape and taste profile.

How are defects counted in Kenyan coffee grading?

Defects are counted by inspecting a 300g sample of coffee. Each type of flaw—like black beans, stones, insect damage, or broken seeds—adds a set number of points. The total defect score determines the grade, ranging from NY2 (highest) to NY8 (lowest). This method focuses on internal quality rather than bean size.

What does SHB mean in coffee grading?

SHB stands for Strictly Hard Bean, referring to coffee grown at high altitudes (4,500–5,000 feet or 1,370–1,520 meters). The cooler temperatures slow growth, producing denser beans with more concentrated flavors. Though more common in Central America, the SHB designation helps indicate bean density and potential cup quality.

How does bean size affect coffee quality?

Larger beans often mature more evenly and have more space to develop complex flavors during roasting. In Kenya, size grading (AA, A, B, etc.) separates beans by mesh screen size, with AA being the largest and generally most desirable for specialty roasters.

Recommended FrontStreet Beans for Exploring Kenyan Grades

FrontStreet Coffee’s Kenya Little Tomato combines the celebrated SL28 and SL34 varieties, both central to Kenya’s premium coffee reputation. Grown at high altitudes and processed via double washed methods, this single origin highlights bright acidity, deep fruitiness, and layered sweetness with notes of tomato, pear, dark plum, blackcurrant, and brown sugar. It’s an excellent example of what top AA-grade Kenyan beans can deliver. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.