The final taste of coffee is determined by several factors, like coffee variety, farm altitude and soil. One of the important factors is also size of the bean.
After coffee is harvested and processed, it has to be sorted by size. Coffee beans are sorted by size into categories using sorting screens. The number indicates the size - 8 means the diameter of the holes in the screen is 8/64 of an inch. That’s the theory.
In practice, the screens are placed successively. The beans first have to pass through the highest number, for example 18. If they don’t pass it, it means the beans are bigger than 18/64 of an inch, or 0.7 cm. The others fall through to number 17, some stay there, some continue, and so on until the smallest screen. The beans are graded with the number of the last screen through which they passed.
Peaberry beans are usually sorted in a special way, because of their different shape. The holes in the screen are rectangular to reflect the peaberry shape.
Some countries do not have any standards for grading coffee, but at the same time, many countries have developed their own classification systems. Luckily, thanks to the screen sizes, they can be roughly translated between each other.
Bigger beans tend to taste better, because they mature for a longer time on the tree and thus should be more developed. Bean size is usually also linked to altitude of growth. But as to every rule, there are countless exceptions. Elephant beans are often too large to support themselves and crack while ripening and become tainted. And even if they are successfully harvested and sorted out, they often crack too early during roasting anyway, tainting the sample.
The most suitable beans are sizes 14, 16 and 18, which offer the best ratio between taste quality and reliability. This is also not true in all cases, though. Most heirloom coffees, typical for Ethiopia
and some other African countries, fall into the smaller bean categories. But they also happen to often be the most interestingly tasting coffees in the world. That’s why Ethiopia
has never really developed any standardisation for coffee sizes, and concentrates purely on cup quality.
In other countries, smaller bean sizes are usually considered inferior, do not qualify as specialty coffee and are sold at a lower price. Even peaberry coffees, considered by many to be the highest quality of bean, fall in the same category as coffee shells in some Latin American countries. That’s because they were traditionally considered a defectively developed, mutated bean.
The only objectively measurable reason to sort coffees by size throughout the world is to guarantee a uniform roast of the beans.
At Coffea, we always strive to offer a broad variety of coffees, even when it comes to size, so that you can compare the difference yourself.