What Does the AA After a Coffee Bean Name Actually Mean?

The letters AA and AB after a coffee bean name indicate the bean's size grade, not its flavor quality. Kenya sorts its green bean harvest by screen size, with AA beans measuring roughly 17 to 18 screens and AB beans falling between 15 and 16. Tanzania and Uganda use similar labels because their grading systems grew out of British colonial trade conventions.

Size is only one dimension. Kenyan grading also weighs defect count and growing altitude, and flavor depends heavily on region and environment. Beans from Nyeri or Kirinyaga often show bright acidity and berry notes, while lower-grown lots can taste flatter even at the same screen size. Colombia grades by size too, but calls its top lots Supremo and Excelso instead.

When purchasing Kenyan coffee, you will often see bean names followed by letter designations such as AA or AB. What exactly do they mean? Why does Kenya place such heavy emphasis on these grades? This article will systematically outline Kenya's green bean grading system based on bean size, explaining the specific classification criteria for each grade—AA, AB, C, PB, E, TT, T, and MH/ML—and pointing out the limitations of size-based grading: bean size is not the sole determinant of flavor quality, and growing altitude and environment are equally critical. It will also introduce the flavor characteristics of coffee from Kenyan growing regions and Front Street Coffee's recommendations for Kenyan coffee.

Observant readers have likely noticed that most coffee beans sold by merchants have an "AA" appended to the end of their names, with the most frequent examples being beans from Kenya—such as Kenya Nyeri AA and Kenya Kirimiri AA.

In fact, it is not just Kenya; coffee from Tanzania, Uganda, and other countries also carries the AA suffix. So the question arises: what exactly does AA stand for? Why do beans from these countries specifically need to be labeled AA?

What does the AA after a coffee bean name mean?

In reality, this "AA" indicates the grade of the coffee beans. Coffee beans are an agricultural product rather than an industrial one, so quality inevitably varies. To regulate quality, a grading system is needed to distinguish the good from the poor. Therefore, when you see a country's coffee beans labeled with AA, you can infer that the country's grading is based on bean size.

Two points need clarification here. First, coffee bean grading standards are not limited to size; they also include defect rate, growing altitude, and other dimensions. Which method is used depends on each country's actual conditions—Front Street Coffee will discuss this in detail another time. Second, not all origins that use size-based grading employ capital English letters. Symbols like AA and AB originate from the British system of units, and most coffee-producing countries still use them because they were historically under British colonial rule. Colombia also uses size as a grading basis, but its grade names are Supremo and Excelso.

However, when it comes to the most famous region for size-based grading, Kenya still takes the crown. The Kenyan government takes an extremely rigorous approach to the coffee industry and is particularly strict about quality control. Now let Front Street Coffee introduce Kenya's size grading rules.

AA: Bean size between 17 and 18 screen sizes. AB: Bean size between 15 and 16 screen sizes. C: This grade's beans range from 12 to 14 screen sizes; because the beans are smaller, they are usually not classified as specialty grade. PB: Peaberry, a relatively rare round-shaped green bean. E: Full name Elephant, meaning elephant bean. Note that the elephant bean here is not the elephant bean variety in coffee (such as Maragogipe or Pacamara), but rather a specially deformed bean similar to peaberry. It is formed by two coffee beans intertwining during growth, appearing as an abnormally large, bloated bean exceeding 18 screen sizes, with extremely low production.

TT: Lightweight beans blown out from AA and AB grades by an airflow sorter. T: Lightweight beans blown out from grade C by an airflow sorter. MH/ML: These two grades are of lower quality, are not processed using the Kenyan washed method, and are generally sold only locally at origin, not exported outside Kenya.

The above is Kenya's official grading system. From this, we can see that AA represents the highest grade in Kenya's classification, meaning the best quality. However, Front Street Coffee previously analyzed the flaws of size-based grading in detail in the review article "Does the Taste of Coffee Beans Relate to Size"—the loopholes are quite obvious.

The size of coffee beans does not directly determine flavor quality. A commonly cited example in the coffee world is this: the same variety planted at 900 meters and 1,700 meters altitude—even if the harvested beans end up the same size, the beans from 900 meters will inevitably taste inferior to those from 1,700 meters, because the growing environment is one of the main factors influencing coffee flavor development.

The above content is compiled by CoffeeHunters, a coffee news website.