How Coffee Beans Are Graded: 3 Main Methods Explained

Ever wondered why one coffee costs twice as much as another, even though they look similar? Much of that price comes down to how the green coffee beans were graded before export — and different countries use very different methods to decide what’s ‘premium.’ Whether you roast your own or just want to understand your bag’s label, knowing how beans are classified helps you buy better.

In short: coffee is graded by altitude (higher is usually better), bean size (measured in 1/64-inch sieve numbers), and defect count (fewer flaws = higher grade). Over 10 countries use these methods, each with exact thresholds — like Kenya’s AA+ requiring 18/17 sieve beans over 7.15mm, or Jamaica Blue Mountain needing under 2% defects.

1. Altitude-Based Grading: Why Higher Elevation Usually Means Better Beans

Many Latin American countries grade coffee by the elevation where it’s grown, because higher altitudes slow growth, allowing more complex flavors to develop in the beans. Cooler temperatures mean slower ripening, which typically leads to denser, harder beans that roast more evenly and taste better.

Countries like Guatemala, Honduras, El Salvador, and Mexico use this system. In Guatemala, the top grade is SHB (Strictly Hard Bean) for beans grown above 1,350m. Below that, you’ll find HB (Hard Bean, 1,200–1,400m), SH (Semi Hard Bean, ~1,000m), and lower tiers like EPW (Extra Prime Washed, 600–800m) and GW (Good Washed, below 600m). Each grade corresponds to both altitude and expected bean density.

2. Sieve (Bean Size) Grading: Bigger Isn’t Always Better, But It Often Is

This method sorts green beans by physical size using perforated metal sieves. The holes are sized in 1/64-inch increments — so a No. 17 sieve has holes 17/64-inch (~6.75mm) wide. The larger the number, the bigger the bean. Big beans often have more even roasts and more complex cup profiles, although some small beans (like Ethiopian or Yunnan varieties) are prized for their unique flavors.

Kenya is famous for its strict sieve-based grades: AA++ beans must be over 7.15mm (using 18+ sieve), followed by AA+, AA (both Screen 17–18), and AB (Screen 15–16). Colombia simplifies its system into Supremo (mostly Screen >17) and Excelso (mostly Screen 15–16.5, with up to 11% of 14-size allowed). Note that peaberry beans (small, round beans) have their own separate sieve scales, usually 8–12.

3. Defect Rate + Sieve Grading: The Real Test of Quality

Most specialty-focused grading systems also count defects — broken, black, sour, or insect-damaged beans that ruin cup quality. The fewer defects, the higher the grade. This method is often combined with sieve sizing for a more complete picture of quality.

Jamaica’s Blue Mountain No.1 requires beans from the 1,700m+ zone, screened through 18/17 mesh, with a maximum 2% defect rate. All Jamaican grades cap defects at 4%. Brazil, the world’s largest producer, uses a hybrid system: defect counting, sieve size, and even cupping tests. Its six-tiered cup quality scale ranges from ‘Strictly Soft’ (excellent balance) down to ‘Rioy’ (harsh iodine notes from soil contact). Ethiopia grades mostly by defects per 300g — with Grade 1 allowing just 0–3 defects, and Grade 8 (over 340 defects) deemed substandard.

Regional Grading Examples

Different origins have unique systems. For example:

• Kenya: AA++ (Screen 18+), AA+, AA (17–18), AB (15–16), C, E, PB (peaberry)
• Ethiopia: Grades 1–8 based on defects in 300g samples (Grade 1 = 0–3 defects)
• Colombia: Supremo (>17 sieve), Excelso (15–16.5 sieve), UGQ (12–14 sieve)
• Brazil: Type 2 (4 defects), Type 3 (12 defects), up to Type 6 (151–225 defects)
• Guatemala: SHB (1,350m+), HB (1,200–1,500m), SH (1,200–1,350m), down to GW (below 600m)
• Jamaica: Blue Mountain No.1 (18 sieve, 2% defects), Grade I (18), Grade II (17), Grade III (16)

Some regions, like Hawaii (Kona) or Indonesia, add additional criteria such as processing method or bean shape. The COE (Cup of Excellence) competition also provides a respected, independent quality score beyond traditional national systems.

Frequently Asked Questions

What does SHB mean on a coffee bag?

SHB stands for Strictly Hard Bean, a Guatemalan grade for coffee grown at elevations above 1,350 meters. These beans are denser and typically have better cup quality due to slower growth at high altitude.

Why are larger coffee beans often considered better?

Larger beans (graded by higher sieve numbers, like 17 or 18) usually develop more evenly and roast more consistently. They often come from higher altitudes, where slower growth leads to more complex flavors — though smaller beans (like Ethiopian or peaberry) can also be exceptional.

How do defect rates affect coffee quality?

Defects — such as broken, black, or insect-damaged beans — negatively impact flavor. Grades like Jamaica Blue Mountain limit defects to under 2%, while Brazil allows higher defect counts in lower grades. Fewer defects generally mean cleaner, more balanced cups.

Do all countries use the same coffee grading system?

No. Countries like Kenya, Colombia, Guatemala, and Ethiopia each have unique systems based on altitude, bean size, or defect counts — or a mix. Some, like Brazil, use cupping tests alongside physical grading.

What’s the difference between AA and AB coffee grades?

In systems like Kenya’s, AA beans are larger (Screen 17–18) and higher quality than AB (Screen 15–16). AA often comes from higher-altitude lots and is prized for its cup profile, while AB is more common and usually less expensive.

Recommended FrontStreet Beans for Altitude & Size Lovers

Try FrontStreet’s Ethiopia Yirgacheffe for bright, floral notes from high-altitude washed processing; their Kenya Gikanda AB offers juicy red fruit from Kenya’s secondary grade (AB, Screen 15–16); and the Colombia Huila Supremo brings balanced body and citrus from classic Supremo-grade (17+ sieve) beans. All highlight how grade affects profile. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.