Bean Size

Coffee is commonly classified based upon screen size, i.e., the size of the holes of a screen sorting system. The screen holes are based on sixty-fourths of an inch, so a #15 is 15/64"; this can also be given in metric equivalents. If nothing else, classification helps ensure bean size uniformity which makes roasts more even (though some roasters eschew uniformity for complexity, at least for certain bean varieties). Additionally, there is a belief that larger size beans have a better taste profile, though that is by no means a uniform rule, especially when comparing different varieties of coffee (there are many inherently smaller varieties that have a "richer" taste than some larger varieties)

In addition to the screen size classifications, there are also regional classifications; for example (from smallest to largest within each series): Terceras, Segundas, and Superior (Central American and Mexican); Excelso or Supremo (Colombia); C to B to AA (African and Indian); and No. 1, Fancy, and Extra Fancy (Kona). A single "named size" may translate to different screen size measures, depending upon the intended export destination (that is, the retail market).Named classifications may have other differences as well: the Kona rankings also account for the average defects per pound.

Size grading is usually done for export purposes, with the lowest grade beans not considered exportable.