Why Grading Matters

Coffee is an agricultural commodity. Like grain, wine grapes, or cacao, the quality of the raw material varies enormously — affected by variety, altitude, soil, processing, and handling all the way from farm to warehouse. Without a standardised grading system, buyers cannot compare lots, farmers cannot be rewarded for quality, and roasters cannot make informed purchasing decisions.

The grading systems used in the specialty coffee industry have two distinct but complementary parts: a sensory evaluation framework (the SCA cupping scale) and a physical assessment framework (green coffee grading by defects and screen size). Together, they give buyers a structured language for describing what is in the bag and what it tastes like.

Understanding grading is useful not just for professionals. It explains why certain coffees cost significantly more, how roasters justify their sourcing decisions, and what terms like “Grade 1” and “85-point coffee” actually represent.

The SCA 100-Point Cupping Scale

The Specialty Coffee Association (SCA) developed a standardised sensory evaluation system that has become the global benchmark for assessing roasted coffee. The scale runs from 0 to 100, though in practice scores below 60 are rarely applied — the relevant range for specialty coffee discussion is 80 to 100.

The thresholds work as follows:

• Below 80: Commodity or commercial-grade coffee. Not classified as specialty.
• 80–84.99: Specialty grade. The baseline for coffees that roasters, importers, and competition-level buyers consider worth paying a premium for.
• 85–89.99: Exceptional coffee. High scores in this range appear on premium single-origin menus and competition lots.
• 90+: Outstanding. Scores above 90 are rare and typically associated with competition-winning lots, micro-lots from exceptional farms, or coffees with unusual processing or variety characteristics. Coffees scoring 90+ often attract significant attention and substantially higher prices at auction.

The score is not a single measurement — it is a composite of ten individual attributes, each scored on a 10-point scale (with 6 as the baseline for a passing attribute). The ten attributes are: fragrance/aroma, flavour, aftertaste, acidity, body, balance, uniformity, clean cup, sweetness, and overall. A trained Q Grader (Qualified Grader, certified by the Coffee Quality Institute) evaluates all ten and totals the score.

Each attribute captures something specific. Acidity describes the brightness or liveliness in the cup — the quality that makes a coffee feel alive and refreshing, not the harsh sourness of an underextracted shot. Body captures mouthfeel — the weight and texture of the liquid. Uniformity checks that all five cups in the cupping set (the standard protocol uses five 150ml cups per sample) taste consistent with each other, penalising lots that produce inconsistent results. Clean cup deducts points for any off-flavours from fermentation defects, contamination, or processing faults.

The Cupping Protocol

The cupping protocol is standardised precisely because sensory evaluation is otherwise unreliable. Variables in water temperature, grind size, brew ratio, and resting time can all alter the perception of a coffee’s qualities. The SCA protocol eliminates those variables:

1. Roast: Samples are roasted to a defined colour range (Agtron 55–60 on whole bean, 63–68 on ground) no more than 24 hours before cupping. The roast profile is intentionally medium — light enough to preserve origin character, consistent enough to allow comparison.

2. Rest: Roasted samples rest for 8–12 hours before evaluation. Fresh-roasted coffee off-gasses CO₂ that can distort flavour perception. Resting stabilises the sample.

3. Grind: Coffee is ground immediately before cupping, to a coarseness slightly finer than a typical drip grind. Pre-grinding is avoided because it accelerates oxidation.

4. Brew ratio: 8.25 grams of ground coffee per 150ml of water — a ratio that provides consistent extraction across samples.

5. Water: Added at 93°C (200°F), poured directly over the grounds, filling each cup to the prescribed level.

6. Crust break: After four minutes, the evaluator breaks the floating crust of grounds by pressing a spoon through it three times, inhaling the aroma released at that moment — this is evaluated as part of the fragrance/aroma score.

7. Tasting: After two additional minutes (allowing the remaining grounds to settle), the evaluator begins tasting by sipping from a spoon. The coffee is evaluated across its full temperature range — from hot through warm to room temperature — because different attributes emerge at different temperatures. Acidity often diminishes as the coffee cools; sweetness sometimes increases; defects may appear or disappear.

Professional Q Graders evaluate multiple samples in a single session, sometimes twenty or more, following this protocol precisely for each. The consistency of the protocol is what makes scores comparable across origins, buyers, and seasons.

Green Coffee Grading: Physical Standards

The SCA cupping score evaluates roasted coffee. But before a coffee is ever roasted, it goes through physical grading at the green (unroasted) stage. Green coffee grading assesses the physical quality of the beans themselves — defects, moisture content, and size — and determines what grade the coffee receives.

Primary and Secondary Defects

The most critical element of green coffee grading is a defect count. The SCA green coffee classification system distinguishes between primary defects and secondary defects, which affect grade differently.

Primary defects are severe quality problems that significantly damage cup quality. These include:

• Full black beans: Beans that have turned fully black due to over-fermentation, disease, or on-tree damage. They contribute harsh, phenolic, medicinal flavours.
• Full sour beans: Beans fermented to the point of souring. They produce a sharp, vinegary off-flavour that contaminates the entire cup.
• Pods (dried coffee cherries): Undried or incompletely processed cherries mixed in with the green beans. They introduce unpredictable fermentation flavours.
• Large stones: Foreign matter that poses a risk to roasting equipment and contamination.
• Large sticks: Similarly, organic foreign matter of significant size.

Even a small number of primary defects can ruin a cup. The grading system assigns each defect type an equivalence value — for example, one full black bean counts as one primary defect, and one pod counts as one primary defect — allowing a total defect count from a 350-gram sample.

Secondary defects are less severe but still affect quality and presentation:

• Partial black or sour beans
• Parchment (beans still with their parchment layer attached)
• Floaters (underdense beans that float during water flotation processing)
• Shells or elephants (malformed bean structures)
• Broken or chipped beans
• Insect damage
• Hull fragments

Secondary defects are counted at a higher equivalence ratio — five secondary defects equal one full defect count in the SCA system.

Grade 1: Specialty Grade

For a coffee to qualify as Grade 1 (Specialty) under SCA standards, a 350-gram green sample must show:

• Zero primary defects
• No more than five secondary defects
• No quakers (underdeveloped beans that fail to roast properly and taste grassy or peanutty) in a roasted sample

This is a strict standard. Even one full black bean disqualifies a lot from specialty grade. This is why specialty-grade green coffee requires careful hand-sorting at origin — often done by workers who sort individual beans on a conveyor belt or table, removing defects visually.

Grade 2 (Premium) allows up to eight secondary defects. Grade 3 (Exchange) and below are commercial grades with increasingly loose defect tolerances.

Moisture Content

Green coffee should have a moisture content of 9–12% (with an optimal range of 10–12% for Arabica) for stable storage and quality preservation. Too low, and the beans become brittle and lose flavour complexity; too high, and they are vulnerable to mould and fermentation in storage.

Moisture content is measured with a calibrated moisture metre at the point of export and again upon arrival at the importer’s warehouse. A significant change in moisture content during transit indicates a storage or container problem.

Screen Size

Coffee beans are sorted by size using screens with circular holes measured in 64ths of an inch. A “Screen 18” bean passes through a screen with holes 18/64 inch in diameter but is retained by a 17/64 screen. Larger screen sizes generally indicate denser, heavier beans that roast more evenly.

Kenya’s famous AA grade is a screen size designation — it means the beans are retained on a Screen 18 or larger, the largest commercially graded size. Kenya AB allows slightly smaller beans. In Colombia, Supremo indicates Screen 17 and above; Excelso includes smaller beans.

Screen size matters because differently sized beans roast at different rates. A bag of mixed sizes produces uneven roasting — some beans over-developed, others under. Specialty lots are screen-sorted to minimise this variation.

How Scores and Grades Are Used

In practice, the SCA cupping score and the green coffee grade work together. A Grade 1 green coffee that scores 82 on the cupping scale is specialty-grade — in the market, but at the lower end. A Grade 1 coffee that scores 88 is in genuinely premium territory. A coffee that passes physical grading with zero defects but scores 78 on cupping is technically not specialty, regardless of its physical quality.

Buyers — importers, roasters, and green coffee merchants — use scores to negotiate prices and make sourcing decisions. Farms and cooperatives use scores as marketing tools, with cupping scores printed on bags and websites as a quality signal. Competition lots for Cup of Excellence, the most prestigious green coffee competition in the world, are evaluated by panels of international Q Graders and typically score above 87 to appear on a published competition list; top lots routinely exceed 90.

For farmers, a score above 85 can mean access to direct trade relationships, significantly higher prices, and the ability to bypass volatile commodity markets. For roasters, a verified score provides a common language with customers — a published cupping score is a commitment to transparency that builds trust.

The grading system is imperfect — sensory evaluation is subjective even when rigorously standardised, and the same coffee evaluated by different Q Graders may receive slightly different scores. But the system provides a workable framework that has transformed how coffee quality is communicated, priced, and valued across the supply chain.