Coffee bean size. How is the coffee graded and what is the quality of the coffee?

In short: Coffee beans are graded by size on sieves whose holes are measured in 64ths of an inch: screen 18 is about 7.1 mm, screen 14 about 5.6 mm. An arabica bean is 8 to 12 mm long. Colombian Supremo means screen 18 and above, Kenyan AA screens 17 and 18. Bigger beans cost more, but uniformity matters more.

Screen unit	1/64 inch per grade
Screen sizes	14 = about 5.6 mm, 18 = about 7.1 mm, 20 = about 7.9 mm
Arabica bean size	8 to 12 mm long, 6 to 8 mm wide
Colombia	Supremo screen 18 and above, Excelso screen 15-17
Kenya	E (screen 20+), AA (17-18), AB (15-16), C, PB, TT, T
El Salvador altitude grades	SHG from 1200 m, HG from 900 m, CS from 600 m

Coffee beans are graded by size on sieves whose holes are measured in sixty-fourths of an inch, which is where the "screen" numbers come from. Screen 18 means a hole of 18/64 inch, about 7,1 mm; screen 14 is 5,6 mm and screen 20 is 7,9 mm. A typical arabica bean is 8 to 12 mm long and 6 to 8 mm wide. Size does not equal quality on its own: what it buys you is uniformity, and uniform beans roast evenly, which is the real reason graders bother.

Are large coffee beans better?

First, let's just say that one bean is not the same as another. Not even from one coffee plant. The differences between beans must then be sorted out using special bean sieves. This is done in a dry mill in the growing country. The sieves have different densities or hole sizes. This makes it easy to achieve the size-uniform coffees that roasters want.

Information on the size of the beans is of value both to the roaster and to the person who eventually drinks the coffee. Before ordering samples, roasters canpredict the coffee's potential from the size indication. In the end, you too can make sure you get quality coffee when you get home by knowing the size. It also affects the taste.

Larger beans are better priced in the coffee market. The standard coffee used is sieved with a sieve size 16 or larger. Smaller beans tend to be used in small-grain blends. That larger beans taste better is supported by the theory that the best flavour profiles are found in well-developed coffees from higher regions and with larger berries. However, size and quality do not always correlate with flavour potential.

Bean sizes and quality coffee designations

However, because the general assumption is thatbigger beans = better coffee, a classification of green coffee has been developed based on bean size. Thus, coffee labelling systems, but different growing countries have different labelling methods. For coffee producers in Colombia, the beans are labeled Supremo or Excelso. In Kenya as AA, AB, PB, etc.

In addition to the appearance of the bean in terms of its dimensions, coffee is marked according to the quality level achieved. In Ethiopia there is a 5 grade system. As a rule, Ethiopian coffees aremarked as G1-5 (short form of "Grade 1" or grade 1). The best quality coffees are graded G1 and G2.

Colombian Excelso and Supremo coffee

These terms are more associated with the marketing ploy to promote sales of coffee from Colombia than the quality of the bean. They were created by the Colombian National Federation of Coffee Growers - Federación Nacional de Cafeteros. These are more interestingly named coffees corresponding to the size 17-15 grading screenfor Excelso and the size 18 and above screenfor Supremo.

Grading of coffee beans from the Americas

Up to 6 groups of coffee bean sizes are used by growers in Central America. The largest beans are classified in a group called Superior. This is the designation for coffees corresponding to sizes 17 and above. Other grades are Segundas, Terceras, Caracol, Caracolli, Caracolillo.

1/64"	mm	Classification	Mexico, Central America	Colombia	Africa and India
20	8	very large	Superior	Supremo	AA
19,5	7,75
19	7,5
18,5	7,25	Large
18	7				A
17	6,75			Excelso	A
16	6,5	Medium	Segundas		B
15	6	Medium	Segundas		B
14	5,5	Small	Terceras		C
13	5,25	"shells"	Caracol
12	5		Caracol
11	4,5		Caracolli
10	4		Caracolli
9	3,5		Caracolillo
8	3		Caracolillo

Table of green coffee bean sizes. Source: coffeeresearch.org

Size-quality typology of coffee from Kenya

The bean grading system for Kenyan coffees is much more sophisticated. It takes into account both the size and quality of the beans. The grading of Kenyan coffees is as follows: E, AA, AB, C, PB, TT, T. The largest coffee beans are from the sievesize 20 and above, so they are really big beans, which are called elephant beans: Elephants= E. On the other hand, the smallest beans are TT beans, which are so light that they have been airbrushed out of AA and AB. The T group is air sorted from the C type and contains quite a few coffee fractions.

As a result of the presumed highest quality of the AA marked beans, these coffees also command a higher price. Kenyan AA coffees are regarded as some of the best coffees worldwide. Sizes for sieves 17 and 18 are achieved through gradual growth at high altitudes. Therefore, in addition to their typical acidity, they have a great sweetness and juiciness.

The AB brandis a combination of grains from sieves sizes 16 and 15. They are such a standard type that means about 30% of Kenya's coffee production per year. Type C is a class below AB. If the coffee is labeled as PB it is "Peaberry" or pearl beans. These are atypical beans. The coffee fruit usually has two beans, in the case of the PB type there was one single bean in the cherry of the coffee tree.

Further grading and classification of coffee

In El Salvador, for example, coffee beans are graded on the basis of the altitude at which they are grown. They use 3 grades with the labels SHG, HG and CS. Coffees grown at an altitude of 1200 m above sea level are SHG i.e. Strictly High Grown. Beans from 900 m above sea level are labeled HG as High Grown and Central Standard or CS for coffees from 600 m above sea level. They have a similar grading system in Guatemala:

Strictly Hard Bean: SHB - 1300 m above sea level.
Hard Bean: HB - 1220 to 1300 m above sea level.
Semi-Hard Bean: SHB - 1050 to 1220 m above sea level.
Extra Prime: EP - 900 to 1050 m above sea level.
Prime: P - 750 to 900 m above sea level.

How are the world's best coffees branded?

Knowing how to label green coffee is particularly useful for coffee retailers and roasters, but baristas and home coffee grinders will also be happy to understand the characters on a packet of coffee. You can better distinguish which coffee you enjoy even more.

However, it still remains a key indicator of the quality of the coffee across the various bean size markings. This is the coffee quality rating by the SCA, which sets the standards for choice coffees - that is, the best coffees in the world.

Frequently asked questions

How big is a coffee bean?

An arabica bean measures roughly 8 to 12 mm in length and 6 to 8 mm across, weighing about 0,15 g green. Robusta beans are smaller and rounder, liberica beans considerably larger and hooked at one end.

How does coffee bean size grading work?

Green coffee is shaken over stacked sieves and the grade is the hole size in sixty-fourths of an inch. Screen 20 is 7,9 mm, screen 18 is 7,1 mm, screen 16 is 6,4 mm and screen 14 is 5,6 mm. A lot is named after the sieve that retains it.

What do grades like AA and Supremo mean?

They are national size labels. Kenyan AA is screen 17 to 18 and AB is 15 to 16, while Colombian Supremo is screen 17 to 18 and Excelso 14 to 16. Central America grades by altitude instead, so SHB or SHG marks beans grown above about 1350 metres.

Are bigger coffee beans better?

Not by themselves. Large beans often come from higher altitudes and slower ripening, which is where the quality reputation comes from, but a big bean picked unripe still tastes flat. Uniformity within the lot matters more than absolute size.

What is a peaberry?

A cherry that grew a single round seed instead of two flat ones, in roughly five per cent of the crop. Peaberries are sorted out separately because their shape roasts differently, not because they are automatically better.

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