How Coffee Beans Are Graded by Size, Defects, and Altitude

Ever wondered how your bag of ‘AA’ or ‘SHB’ coffee beans earned that label? From Kenya to Brazil, coffee is graded using different systems based on bean size, physical flaws, and elevation—but the methods, numbers, and terminology vary wildly. If you’ve seen grades like AA, PB, or NY2 and didn’t know what they meant, here’s the full breakdown.

In short, coffee is graded by passing beans through numbered sieves (AA often means 17/18 mesh), counting defects per 300g sample (NY2 is top Brazilian grade), and ranking beans grown at higher altitudes (SHB means 4,500–5,000 feet). Each system serves a different origin and tells you something specific about bean quality.

Coffee Bean Size Grading with Screens

Coffee beans are commonly graded by size using mesh screens with holes measured in 1/64-inch increments. Each screen is numbered according to its hole diameter—for example, a screen with 18/64-inch holes is labeled ‘18’. Beans are shaken over these screens, and those that fall through smaller holes are eliminated. The beans that remain on larger screens are sorted by grade.

After multiple screenings, beans are assigned grades including AA, A, B, C, and PB. AA is the highest grade, followed by A, B, and C—with C-grade beans often used for animal feed. PB, for peaberry, refers to small, round beans that occur when only one seed develops inside the coffee cherry. Peaberries are often considered to have unique flavor profiles and are usually more expensive. This size-based grading system is widely used in countries such as Kenya, New Guinea, Puerto Rico, Zimbabwe, Tanzania, and Uganda.

Defect Counting: The Original Coffee Grading Method

The oldest grading method counts physical flaws in a 300g coffee sample. Inspectors examine the beans on a black surface to easily spot imperfections. Each type of defect—like black beans, stones, insect damage, or husks—adds a specific number of points to the sample’s score.

For example, one black bean equals one defect point, a small stone also equals one point, a large stone counts as five, five broken beans equal one point, five insect-damaged beans count as one, two sour beans make one point, one large dried fruit skin equals one point, two medium skins count as one, three small skins equal one, five unhusked beans are one point, and three shell beans count as one. The total defect score determines the coffee’s grade, ranging from NY2 (best) to NY8 (lowest) in Brazil. There is no NY1 grade. Indonesia uses a similar system with grades Gr1 to Gr6, while Ethiopia’s highest grade is Gr2. This method remains in use across many producing regions, especially where bean uniformity is less emphasized than cleanliness and freedom from defects.

Altitude-Based Coffee Grading

Coffee is also graded by the elevation where it’s grown, as height affects bean density, hardness, and flavor development. Higher altitudes typically produce denser, harder beans with more complex flavors and brighter acidity due to slower maturation. This is sometimes referred to as ‘hardness’ grading.

The common altitude categories include: SHB (Strictly Hard Bean) for beans grown at 4,500–5,000 feet; GHB (Good Hard Bean) at 3,000–4,500 feet; HB (Hard Bean) at 2,000–3,000 feet; and Pacific for beans grown at lower elevations around 984–3,280 feet. Countries like Guatemala, Costa Rica, El Salvador, Mexico, Honduras, and Haiti rely on this altitude-based classification to indicate bean quality and potential cup profile.

Frequently Asked Questions

What does AA mean in coffee grading?

AA is a grade given to high-quality coffee beans, typically the largest and often considered the best of the lot in size-based grading systems. It is commonly used in countries like Kenya, where AA beans are screened through 17/18 mesh and are known for their high cup quality and premium status.

What is a peaberry coffee bean?

A peaberry, often labeled as PB, is a rare type of coffee bean that forms when only one round seed develops inside a coffee cherry instead of the usual two flat beans. Peaberries are usually smaller, rounder, and often thought to have distinct flavor characteristics. They are sorted separately and often command higher prices.

How are defects counted in coffee grading?

Defects are counted by inspecting a 300g sample of coffee beans. Different types of flaws—such as black beans, stones, insect damage, or chipped beans—are assigned specific point values. The total defect score determines the coffee’s grade, with lower scores indicating higher quality. For example, the Brazilian NY2 grade is the highest, while NY8 is much lower.

What does SHB mean in coffee?

SHB stands for Strictly Hard Bean, referring to coffee grown at high altitudes between 4,500 and 5,000 feet. These beans are denser and harder due to slower growth at elevation, often resulting in a more complex and vibrant cup profile. SHB is a common grade in Central American countries.

Why are coffee beans graded by size?

Coffee beans are graded by size to ensure uniformity, which affects roasting consistency and extraction during brewing. Larger beans often mature more evenly and are associated with higher quality in many origins. Screens with specific mesh numbers are used to separate beans by size during grading.

Recommended FrontStreet Beans for Grading Insights

Explore FrontStreet Coffee’s Ethiopia Yirgacheffe for bright, floral complexity often found in high-altitude beans, and Kenya AA for the bold, wine-like acidity typical of AA-grade lots. For something unique, try their peaberry offerings—these rare round beans often highlight the sorting precision behind PB grades. All three showcase traits tied to the grading systems discussed. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.