The Three Major Grading Standards for Green Coffee Beans! Detailed Explanation of Green Coffee Bean Grade Classifications in Different Countries! What Do AA and G1 Mean in Coffee Beans?

Understanding Coffee Bean Classification Systems

As we all know, coffee beans are agricultural products. Unlike industrial products that can be replicated with near-perfect precision, agricultural products vary in quality. Therefore, to establish consistent quality standards, a corresponding system is needed to regulate coffee bean quality—both for quality assurance and to provide reference value for buyers purchasing green beans. This is how "grading" systems came into existence.

However! Since coffee beans are cultivated worldwide across vast geographical spans, with each growing region having different geographical environments and cultivation methods, there is no unified standard for grading coffee beans. Ultimately, each coffee-producing region establishes its grading standards based on local conditions and adapting to national circumstances.

Currently, coffee bean grading standards primarily fall into three main categories: size, altitude (hardness), and defect rate. Although mainly divided into these three types, they are not the sole criteria for determining grades. Many countries employ multiple methods to grade coffee beans, such as using both altitude and size. Some countries even use cupping to address deficiencies in their original grading systems after determining grades. In summary, while these three are the most common grading methods, they are not the only indicators.

I. Screen Grading Method (Bean Size)

Screen grading is straightforward—it involves passing coffee beans through specific screen sizes to directly measure their size, then grading them accordingly. Larger beans receive higher grades (with elephant beans being an exception). As FrontStreet Coffee mentioned in the article "Kenya Grading," this grading method is the earliest coffee bean classification system, so some countries that started cultivating coffee early use this method for grading their coffee beans.

We all know that bean size cannot serve as a criterion for judging coffee flavor quality. The reason for this grading approach is that many growing regions believe that coffee beans that are full, uniform, and large indicate complete maturity. These beans not only undergo more comprehensive flavor development during growth but also facilitate more even roasting when of similar size, resulting in more consistent coffee flavors. Kenya is a coffee-producing country that grades solely by bean size, with its grading system as follows:

In addition to the grades mentioned above, Kenyan coffee also has secondary grading indicators such as Top/Plus (+)/FAQ. However, these are grading methods used by local coffee research institutions and green coffee traders (based on cupping flavor ratings). Therefore, FrontStreet Coffee will not elaborate further here—interested friends can click on the Kenya article above to learn more. Colombia also uses size grading for exported coffee beans, but coffee beans must first meet qualification standards. The standards are as follows: size must be above 14 mesh, with at least 50% of green beans larger than 15 mesh, no more than 5% of green beans between 12-14 mesh, free from pests, uniform color, no off-flavors, clean flavor, moisture content not exceeding 12.5%, and cumulative defects not exceeding 24 points.

When these conditions are met, coffee beans can obtain export qualification and receive the "Excelso" (superior grade) designation. They then undergo another round of size grading before being exported. Their size grading is as follows:

II. Altitude/Hardness Grading Method

As FrontStreet Coffee often mentions, coffee bean size cannot directly determine flavor development. Therefore, some Central and South American countries use coffee cultivation altitude to determine bean grades. Because when coffee beans are grown at higher altitudes, they can absorb more substances, increasing their density and resulting in more outstanding flavors. Coffee-producing countries such as Panama, Costa Rica, Guatemala, and Honduras all use this model. However, since each country's altitude varies, their grading systems adapt to local conditions. Below is an overview chart of altitude grading.

III. Defect Grading Method

Precisely because coffee beans are agricultural products, coffee fruits are easily affected by negative factors during growth (poor development, pests, diseases, mold, etc.), which then become defective beans. The presence of defective beans can significantly negatively impact coffee flavor, which led to the emergence of grading standards based on the proportion of defective beans in green coffee.

Early Ethiopia was a coffee-producing country that used the defect rate grading system, and it's also the most typical example of adapting to local conditions. The reason for adopting defect grading is that Ethiopia's average altitude is relatively high, making it unnecessary to use altitude as a coffee bean grading standard. Additionally, most of Ethiopia's coffee cultivation and harvesting follows a mixed model: mixed cultivation and mixed harvesting. Previously, few people made special distinctions, resulting in coffee batches with various varieties and inconsistent sizes. Therefore, the size grading system couldn't be used to determine grades, leaving only the defect rate method. Ethiopia's earliest grading system was as follows:

Similarly, defect rate grading, like size grading, has its flaws. Therefore, in 2009, Ethiopia launched a completely new grading system: on top of the original defect rate grading, cupping scores were added for comprehensive evaluation.

Combined Grading Methods

Next, FrontStreet Coffee will share some grading systems that combine multiple methods. First, let's look at Jamaica, home of the "coffee emperor"! Jamaica's Coffee Industry Board (CIB) grades coffee grown in the Blue Mountains based on cultivation altitude (cupping performance), green bean size, and defect rate (as well as moisture content, color, and uniformity).

Indonesia's coffee grading system combines defects and size—first grading based on the number of defects in a 300g green bean sample, then screening by size.

Indonesia's G1 grade requires 18 mesh, which is already considered Indonesia's highest national standard grade. However, PWN's Golden Mandheling has higher standards in terms of mesh size, defects, and other aspects, with even better quality—but that belongs to PWN's own corporate standards (for details, you can learn more about "Golden Mandheling"). Then there's Brazil! Because Brazil's grading system originates from the Green Coffee Association of New York, its grade indicators begin with "NY" (New York). This system combines defect rate and size—first evaluating coffee beans by defect rate, then screening by size.

It's worth mentioning that Brazil does not have an "NY1" grade. This is because Brazil's coffee beans must not exceed 6 defects per 300g to achieve the second grade (NY2), so the first grade should theoretically have even fewer defects. However, Brazil believes that coffee is an agricultural product and uses purely mechanical harvesting, making it impossible to achieve zero defects. Therefore, Brazil's highest grade caps at NY2. Finally, FrontStreet Coffee would like to briefly mention that coffee bean grades only relate to green beans and are concerns for green bean suppliers and roasters. As consumers of roasted beans, we don't need to pay too much attention to them. This is because low-grade green coffee beans are mostly consumed domestically in producing countries, and because grades are not entirely tied to quality. Take Ethiopia's G1 and G2, for example—the only difference is the number of defects. Roasters would not tolerate defects in their products and will screen them out both before and after roasting. Therefore, enjoying the various delicious flavors of coffee is what we as roasted bean consumers should focus on.

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