Letters such as AA, AB, or PB on a Kenyan coffee label are often perceived as direct quality grades—like medals of excellence. In reality, they denote purely physical attributes: the size, shape, and density of the green beans after dry milling. It is also not the case that one tree yields exclusively "AA" and another "AB." All these grades originate from the very same harvest, the same coffee cherry, and the same Kenyan hillsides.
The Kenyan grading system is among the most meticulous in the world, serving roasters and Specialty coffee enthusiasts alike as a key to understanding how the coffee behaves during roasting and what to expect in the cup.
Kenya almost exclusively utilizes the washed process. The initial grading begins immediately after harvest.
After the coffee cherries undergo wet processing (notably Kenya's signature double fermentation), dry on raised African beds, and are hulled of parchment at the dry mill, mechanical grading begins. It relies on three primary principles:
| Grade | Screen size / specification | Profile and physical characteristics |
|---|---|---|
| E (Elephant) | Screen 18+ (above 7.2mm) | Oversized beans formed when two seeds fuse together inside a single cherry. They often split during processing, leaving behind characteristic "ears." Rare and full-bodied, yet requiring careful heat application during roasting. |
| AA | Screen 17/18 (approx. 7.2mm) | The largest and typically densest standard flat beans. They deliver pronounced acidity and exceptional complexity, though they require a substantial heat transfer during roasting. |
| AB | Screen 15/16 (6,8–7.2mm) | A combination of grade A and B beans. Accounting for approximately 40% of total production, it is typically more balanced in the cup, with softer acidity and a rounder body than AA. |
| PB (Peaberry) | Approx. screen 17 (round) | A natural mutation (approx. 5–10% of the crop) where a single round bean develops inside the cherry instead of two. It is very dense and rolls exceptionally evenly in the roaster drum. The flavor profile is typically concentrated and remarkably sweet. |
| C | Screen 14/15 | Smaller, thinner beans screened out from the AB category. When sourced from high altitudes, they can surprise with their cup clarity, though they generally trade at a lower price point. |
| TT | Air classification | Lighter beans separated by airflow from the E, AA, and AB grades. They have lower density and less developed sugars. |
| T | Screen below 12 / fragments | Broken, damaged, or very small fragments. Primarily destined for commercial blends on the domestic market. |
| MH / ML (Mbuni) | Naturally dried | Cherries that fell from the tree or dried out directly on the branch (mbuni). A coffee with a higher incidence of defects, typically harsher, astringent, or grassy. |
The most prevalent consumer myth (and a frequent topic of debate on forums like Reddit) is the assumption that AA automatically equates to the finest coffee. Physical bean size, however, is merely one parameter.
Bean size and cup quality are two distinct metrics. For this reason, Kenyan coffees undergo sensory evaluation (cupping) independently after size grading to assess clarity, acidity, body, and overall flavor profile. A high-scoring AB or PB lot can easily outperform an average AA lot from the same farm.
Why, then, are larger AA beans so prized? The primary factor is elevation. Coffee trees cultivated at altitudes above 1700 m a.s.l. mature more slowly, accumulating more sugars and organic acids, resulting in exceptionally dense, large beans. Bean size in AA is thus a direct consequence of exceptional terroir, yet not an automatic guarantee of cup quality.
The primary reason coffee in Kenya is strictly graded by size is roasting consistency. If you were to roast small C-grade beans together with massive E or AA beans in a single drum, the smaller beans would burn before the larger ones were properly developed inside.
Kenyan beans graded AA and PB are renowned for their exceptional density. During roasting, they require a higher initial charge temperature to ensure the heat penetrates all the way to the core without scorching the surface.
In most cases, AA delivers a better cup profile than AB, though not always. In the roastery, taste is what ultimately matters most. If you see an AB grade in our selection, it does not mean it is inferior coffee; it is often an outstanding coffee at a more accessible price.
Absolutely. At the Nairobi Coffee Exchange auctions, AA is highly sought after as a prestigious grade, which drives up its price. However, AB coffee from the same farm offers equally complex fruity notes (blackcurrant, citrus) with slightly milder acidity, often representing the best value for money.
Since only a single seed develops inside the cherry instead of two, this lone bean absorbs all the nutrients. PB beans are naturally round, dense, and absorb heat more evenly during roasting. In the cup, this often translates into more pronounced sweetness and vibrant acidity.
Grade E represents a genetic anomaly where two beans within a cherry literally fuse into a single giant one. However, during pulping and drying, they shatter easily and create irregular fragments. Due to their low volume, they are usually separated or blended into special microlots.
We bring you the very first specialty coffee from this year's fresh harvest. This Kenya is truly special to us – we selected it personally during our trip to Africa in February 2026, where we cupped more than 400 samples. The Kagumo washing station, established back in 1951 on the volcanic slopes of Mount Kenya, won us over immediately.
