Coffee has, in many countries, been graded by size longer than it has by quality. in fact, the two things are still considered related, although technically they are not. Different countries will use different terminology around their grading.

Grading is generally done with sieves, numbered to indicate the size of the perforations. The even numbers (such as 14, 16 and 18) are used for Arabica, while odd numbers are used for Robusta. Once the coffee is hulled it is mechanically shaken through layers of these sieves to separate out the different grades.

Peaberry is a grade based on the smallest whole beans. Peaberries occur when a coffee berry has just one seed inside rather than two. They are considered to have a greater intensity of flavor, although this may not be universally true. it is always an interesting experience to compare the flavor of the peaberry selection of a coffee against that of the larger beans.

While larger beans aren’t necessarily better, the advantage of having a relatively small size range is that roasting the coffee is easier, and the resultant roast is likely to be more uniform. This is because coffee beans of different sizes also have different densities. During roasting, the smaller coffee beans, or the less dense ones, will roast much faster than the larger, or denser, beans. This will mean that at least a portion of the coffee in a mixed batch will not have reached the ideal roast level.

Common Size Grades

These are the most common sizing grades used in the following coffee-producing areas.

Colombia

Supremo and Excelso are very common grades. Excelso is screen sizes 14-16, and is smaller than Supremo, which is sizes 16-18 (or above). Colombia pioneered how it sold its coffee, and uses grades like this to emphasize its quality.

Central America

The larger sizes are traditionally referred to as Superior (emphasizing quality through size). Peaberries are known as caracol.

Africa

The largest screen size is generally considered AA, then AB and then A. Coffee-producing countries such as Kenya have a strong focus on quality relating to size grading and AA lots tend to sell for higher prices in their internal auction system.