Green coffee grading

Before a coffee is ever roasted or tasted, someone tips a weighed sample of raw beans onto a lit table and picks through it by hand, pulling out everything that is broken, blackened, mouldy, insect-bored, or not a coffee bean at all. That is green coffee grading: the physical half of quality, done with eyes and a scale rather than a spoon.

It sits alongside — not inside — the tasting half. Cupping and the 100-point score tell you how the coffee tastes; grading tells you what condition it arrived in. Under the SCA’s newer Coffee Value Assessment, these are formally two of the four separate assessments, and a lot has to survive both.

The single most important thing to understand up front: there is no one global grading standard. The specialty trade uses one logic, Brazil and the New York exchange use another, and individual producing countries use their own again. They count different things, in different sample sizes, for different reasons.

Where defects come from

A defect is a physical fault in an unroasted bean — a bean that is the wrong colour, the wrong shape, hollow, chewed, or rotten. The SCA’s own grading primer sorts the causes into three windows, which is the most useful framing available because each one belongs to a different person:¹

• Pre-processing — “something resulting from the farm and from nature.” Insects, disease, a cherry picked underripe or left to overripen on the branch.
• Processing — “something from mishandling or missteps in the process of removing seed from fruit.” Fermentation run too long or too warm, drying done too fast or too slow.
• Storage — damp warehouses, bad bags, time.

So a defect count is not just a quality reading. It is a diagnostic: it tells a buyer which stage of the chain went wrong, and therefore who to talk to about it. See Coffee fermentation and Dry milling for the two stages that generate most of them.

The two categories

The specialty system splits defects into primary (also called category 1) and secondary (category 2), and treats them completely differently.

Primary defects are contamination and rot — a fault that carries into the cup no matter how much good coffee surrounds it. Secondary defects are damage to beans that are otherwise sound. As the SCA’s primer puts it: “Primary defects will knock your coffee out of ‘specialty’ status with just 1 or a couple present. If your coffee has a few Secondary defects it may still qualify as ‘specialty.’”¹

The logic is the same one this wiki records under Fine Robusta and Specialty coffee: one mouldy bean taints the batch; five chipped ones do not.

Category 1 — primary	Category 2 — secondary
Full black bean	Partial black bean
Full sour bean	Partial sour bean
Dried cherry or pod (missed at pulping)	Broken, chipped or cut bean
Fungus damage	Shell (a hollow, ear-shaped half bean)
Foreign matter — stones, sticks, nails	Floater / bleached bean
Severe insect damage	Slight insect damage
	Withered bean
	Parchment or husk fragments

Causes, where a source names them: a full black bean is brown-black, shrivelled and often split, from overripe harvesting or excessive fermentation; a full sour bean comes from delays between picking and depulping, uncontrolled fermentation, or storing coffee too wet; dried cherry is fruit missed at the pulper; stones and sticks are simply poor sorting at the mill; floaters and bleached beans are low-density beans from uneven or rapid drying and poor storage.²

Quakers are the odd one out. A quaker is an underripe bean, and it is effectively invisible in green form — it only reveals itself in the roaster, refusing to brown and coming out pale, papery and peanut-flavoured.² That is why grading standards check them on a roasted sample rather than a green one (see Fine Robusta, which sets its quaker limits on a 100 g roasted sample), and why they are the one defect a green grader cannot catch.

Counting: the “full defect”

Raw defect counts would be misleading — a stone is not the same problem as a chipped bean. So the specialty system converts everything into a common unit, the full defect, using an equivalence table. Severe faults count one-for-one; cosmetic ones take several to make one full defect.

	Defect	Equals one full defect
1	Full black, full sour, fungus damage, dried cherry, foreign matter, severe insect damage	1
2	Partial black	3
3	Partial sour	3
4	Broken / chipped / cut	5
5	Shell	5
6	Quaker (roasted sample)	5
7	Slight insect damage	10

Source: a green-coffee trade reference summarising the SCA protocol.³ These specific ratios come from one source and are not confirmed against a published standard — see the callouts below. One procedural rule this wiki already records under Fine Robusta is worth repeating: defect counts are recorded as whole numbers, always rounded down. Half a defect is no defect, which quietly favours the producer.

The specialty threshold

The rule almost everyone quotes is that a specialty-grade lot must show zero primary defects and no more than five secondary defects in a 350 g sample.⁴⁵ It is repeated consistently across the trade, and it is the physical half of the definition set out in Specialty coffee — the other half being a cup score of 80 points or above, below which a coffee “must remove ‘specialty’ classification” and is “considered commercial grade.”¹

Both halves have to hold. A lot that cups at 88 but carries a full black bean in the sample is not specialty; a spotlessly clean lot that cups at 78 is not either.

The five-grade SCAA ladder

Behind that single pass/fail line sits an older, fuller ladder. The 2004 SCAA classification does not stop at “specialty or not” — it sorts all green coffee into five named grades, counted in 300 g rather than 350 g:⁶

	Grade	Name	Full defects in 300 g	Other requirements
1	1	Specialty	≤ 5	No primary defects, no quakers, moisture 9–13%
2	2	Premium	≤ 8	Primary defects allowed, ≤ 3 quakers, moisture 9–13%
3	3	Exchange	9 – 23	≥ 50% by weight above screen 15, ≤ 5% below screen 14, ≤ 5 quakers, moisture 9–13%
4	4	Below standard	24 – 86	—
5	5	Off grade	> 86	—

Grades 1 to 3 also carry a screen-size tolerance of 5% above or below the size stated on the bag — so “screen 17” is a promise with a stated margin, not a description.⁶ Grade 3 is named “Exchange” because that is the floor for delivery against a commodity futures contract; everything at Grade 4 and below is coffee that trades on price alone.

Two things fall out of this table. The first is that the familiar specialty threshold is the top rung of a commercial ladder, not a separate system — the specialty trade kept Grade 1 and quietly discarded the rest. The second is that the whole ladder is defect-count-only below Grade 1: nothing in Grades 2 to 5 asks how the coffee tastes.

To verify — the SCA has no published green grading standard

This wiki’s Specialty coffee and Dry milling notes already record the underlying problem, and it applies to this entire page: SCA-110 Green Coffee: Grading, Specifications, and Test Methods is listed on the SCA’s own standards page under “Standards in Development”, not among published standards. Everything above is inherited from the older 2004 SCAA green grading system and from trade practice built on it. Do not quote any figure here as a current, published SCA rule.

To verify — 350 g or 300 g? Two eras, not one number

The specialty threshold is quoted against a 350 g sample by current trade and training material.⁴⁵ But the 2004 SCAA classification in the table above, the FAO classification annex (“a 300g sample of green coffee”), Royal Coffee’s grading explainer (“Using 300g of green coffee, a grader will pick and categorize different defects”) and the trade reference behind the full-defect table all count in 300 g.⁶⁷⁸³ The SCA primer itself mentions only “a 100g-300g sample which was cleaned by hand,” without naming an official figure.¹ The best available reading is now that 300 g belongs to the older SCAA classification and to commercial systems, and 350 g to the newer SCA-derived specialty practice — a difference between generations of standard rather than a contradiction. No source read here states that migration outright, and with SCA-110 unpublished there is nothing to settle it against, so still treat any sample weight as belonging to a named system rather than as “the” grading sample size.

To verify — a competing set of grade tiers

The trade reference that supplies the full-defect table describes the specialty grades as “Grade 1: ≤3 full defects, no primary defects, no quakers” and “Grade 2: ≤8 full defects. Still specialty eligible if cup score hits 80+.”³ Its Grade 2 figure matches the SCAA ladder exactly, which strongly suggests the tier names are inherited from that 2004 classification rather than invented. Its Grade 1 figure does not: ≤3 full defects against the SCAA’s ≤5.⁶³ One of the two is wrong and no published SCA standard exists to say which, so both are recorded and neither is stated as fact. A related wrinkle: the SCAA ladder allows Grade 1 ≤5 full defects, while the widely quoted specialty rule allows ≤5 secondary defects.⁶⁴⁵ Those are not the same allowance — five full defects could be twenty-five broken beans once the equivalence table is applied, five secondary defects only five. Read any “five” on this page against the unit it is counting.

Moisture, and the other numbers on the sheet

Defects are what a grader counts, but they are not the only thing recorded. A green grading sheet also carries moisture content — how much water is in the beans, read on a meter in seconds — and moisture is a pass/fail criterion in its own right.

The two ranges in circulation are not the same:

	Range	Whose	What it is
1	9–13%	2004 SCAA classification, applied to Grades 1, 2 and 3 alike6	A wide commercial tolerance
2	10–12%	Quoted as the current SCA allowance by roasting-software and training material5	A tighter specialty working range

The reason for the tighter band is physical and runs in both directions. Above about 12%, free water and mould risk climb and shelf life collapses — Cropster’s guide says readings above 12% are unacceptable and can cost significant cupping points.⁵ Below about 10%, the coffee has been dried too hard and goes woody or papery, losing the aromatics it was dried to keep. Neither end is a taste preference; both are damage. This wiki’s Dry milling note records the same window from the mill’s side (hulling at roughly 11–12%, storage capped near 12–12.5%), and Washed process and Natural process cover the drying that sets it.

To verify — "10–12% according to the SCA"

The 10–12% figure is attributed to the SCA by the sources that quote it,⁵ but as the callout above records, SCA-110 Green Coffee is still an unpublished standard. There is no SCA document to check the number against. Treat 10–12% as current specialty practice, and 9–13% as the older SCAA classification tolerance — not as two versions of one published rule.

Beyond moisture, specialty buyers routinely measure two things that no grading standard requires: bean density, which tends to rise with altitude and predicts how a lot will behave in the roaster, and Water activity, which measures how much of the bean’s water is free to cause trouble. Both are buyer practice rather than grade criteria, and neither has a numerical threshold in any published standard — see Water activity for how badly the circulating figures disagree.

The bench itself

Green grading is a visual judgement, so the conditions it is made under are part of the protocol rather than housekeeping. Current guidance is to sort the sample on a matte black mat under full-spectrum lighting at around 4000 K and 1200 lux.⁵ Black because a chipped or bleached bean disappears against a pale surface; a fixed colour temperature and brightness because “is this bean sour-brown or just dark?” is a question warm domestic lighting will answer differently every time. Two graders using different lamps produce different defect counts on the same coffee, which is the whole problem a standard exists to remove.

The other systems

Brazil / New York

The second major method is the Brazil/New York system, used to write and settle physical contracts. It cuts the defect list along a different seam: instead of severe versus cosmetic, it separates intrinsic defects — faults in the beans themselves, “like insect damage or shells” — from foreign defects, meaning everything in the bag that is not coffee.⁸

Royal Coffee’s green-analytics series names the difference in purpose plainly: the SCAA format places “a heavier emphasis on flavor impact,” while the Brazil/New York method is about “helping to secure contracts and protect equipment.”⁸ That second half is literal — a stone in a bag of coffee is a broken grinder, and a system built for commodity volume cares about that in a way a cupping-led standard does not.

Size and defect classes together

Older and origin-level systems often grade on bean size first, then defects. The FAO’s classification annex sets out a five-grade size ladder measured on screens — “Grade 0: beans held back by screen No. 18 (7mm holes)”, then Grades I to IV falling through screens 16, 14, 12 and 10 in turn — and, separately, four defect classes:⁷

Class	Defects in a 300 g sample
Extra prime	fewer than 15
Prime	15 to 30
Superior	30 to 60
Regular	60 to 120

with a hard ceiling: “Under no circumstances should the total number of defects exceed 120 for a 300g sample.”⁷

Set that against the specialty rule and the gap is startling. A commercial lot can carry 120 defects and still be gradeable; a specialty lot is allowed five, none of them primary. That single comparison is the clearest illustration on this wiki of what the word specialty actually costs at the mill.

Screen numbers themselves are measured in sixty-fourths of an inch, and in practice run from about 10 to 20 — “super small beans fall through 10/64 inch (4mm) diameter holes while super large beans are suspended… holes with a 20/64 inch (8mm) diameter.”¹ Screen 15 is therefore 15/64 inch, about 6 mm, and screen 18 about 7.2 mm.⁹ This is the same screen grading described mechanically under Dry milling; a screen number describes bean size, not bean quality, though most origins price the two together.

Sizing is its own bench procedure, separate from defect counting. Under the SCAA classification, 300 g of hulled coffee is shaken through a stack of screens 14, 15, 16, 17 and 18, and what each screen holds back is weighed and recorded as a percentage — in practice, graders often run 100 g instead for speed on lower-quality lots.⁶ The output is a size distribution, not a single number, which is why a bag labelled “screen 17” comes with the 5% tolerance noted above rather than a guarantee.

To verify — which country the FAO classes belong to

The FAO annex presents these size grades and Extra prime / Prime / Superior / Regular classes as “commercial green coffee standards” alongside summaries of the SCAA and Brazil/New York systems, but the page as fetched names no country, authority or publication date for them.⁷ The engine report behind this note described the same annex as “origin-specific.” Until the governing body is identified, treat these classes as a commercial standard, not a global one.

Export preparation grades

A third layer sits on the bag alongside all of this: short abbreviations that describe how high the coffee grew and how hard it was sorted, rather than counting anything itself. They come from exporters, not from any standards body.

• SHB (Strictly Hard Bean) and SHG (Strictly High Grown) are the Central American altitude grades, generally meaning coffee grown above about 1,200 m, with HB (Hard Bean) roughly 1,000–1,200 m and softer grades below that.⁹ The logic is that colder, slower growth at altitude produces a denser, harder bean — which is why the same fact gets expressed as “hard” in one country and “high grown” in the next. See Terroir for why altitude does this.
• EP (European Preparation) is a sorting standard, not an altitude one: an extra hand- and machine-sorting pass to strip out defects and undersized beans before export.⁹

Neither says anything about how the coffee tastes. An SHB EP lot has been grown high and cleaned hard, and can still cup at 76.

To verify — altitude bands and the EP defect limit

Only one source consulted here defines these, an importer’s guide page, and its figures are single-sourced: SHB above 1,200 m, HB 1,000–1,200 m, and EP as “a sorting standard that limits defects to 8 full defects per 300 g sample.”⁹ The same page writes SHB as “Strictly High Bean” where the trade normally expands it as Strictly Hard Bean. Altitude thresholds for these grades are set by national regulation and vary by country — Costa Rica’s SHB is not Guatemala’s — so no single figure should be read as the definition. The EP defect limit in particular matches the SCAA Grade 2 allowance exactly,⁶ which may be a real inheritance or may be the page conflating the two.

National systems

Beyond those, most producing countries run their own grade names on their own logic — some on screen size, some on defect count, some on cup quality, most on a combination. A grading overview consulted here covers separate systems for Ethiopia, Kenya, Colombia, Brazil, Central America and Indonesia.⁴ This wiki records the Ethiopian grade thresholds only with a warning attached (see Dry milling), because the state bodies that actually set them — the Ethiopian Coffee and Tea Authority and the Ethiopia Commodity Exchange — publish far less per-grade detail than trade sources imply. The same caution applies to Kenya, Colombia and Brazil: a grade letter on a bag is meaningful within its origin and rarely translates across borders.

Why it matters

Grading is what makes coffee sellable at a distance. A buyer in Berlin wiring money for a container in Sidama is trusting two numbers — a cup score and a defect count — to stand in for the coffee itself. The score is produced by cupping and underwritten by the Q Grader licence; the defect count is produced here, and it is what the dry mill’s gravity tables, optical sorters and hand-sorting lines exist to move.

It also explains a cost structure that is otherwise invisible. Getting from 120 allowable defects to zero primaries is not a farming achievement — it is machinery, labour and thrown-away coffee. Every bean pulled off the sorting table is weight the producer does not get paid for. That is a large part of why specialty lots cost what they do, well before any auction at Best of Panama or Cup of Excellence adds a premium on top.

And it is the reason Robusta has needed its own route. Almost all robusta is dried whole and milled cheaply at volume, which makes specialty defect limits very hard to hit — hence Fine Robusta, a parallel standard with its own defect table run by the Coffee Quality Institute rather than the SCA.

Related

• Specialty coffee — the grade this counting decides half of
• Fine Robusta — the parallel defect standard for the other species, with published limits
• Water activity — the third green-coffee number, measured alongside moisture and not required by any standard
• Dry milling — the machinery that removes the defects counted here, and where screen sizing physically happens
• Terroir — why altitude grades like SHB exist at all
• Cupping · SCA cupping protocol · Coffee scoring — the tasting half of the same judgement
• Coffee Value Assessment — the SCA framework that makes physical condition a formal, separate assessment
• Q Grader — the licence that certifies someone to do both halves
• Coffee fermentation · Washed process · Natural process · Wet hulling — the processing stages where most defects are created or avoided
• Specialty Coffee Association · Coffee Quality Institute · Ethiopian Coffee and Tea Authority — the bodies that write or ought to write the rules
• Green coffee buying · C-market — where a defect count turns into a contract and a price
• Ethiopia · Kenya · Colombia · Brazil · Sidama — origins with their own national grade systems

Official links

• Official site — SCA Coffee Standards (including the in-development SCA-110 green coffee grading standard)
• Official site — SCA education, How to Grade Green Coffee

Footnotes

1. SCA (sca.training) — How to Grade Green Coffee: Size, Defects, Scoring Quality — SCA education material by Adam S. Carpenter, 13 January 2021; confirmed via WebFetch; source of the three defect origins, the primary-vs-secondary consequence, the 80-point line, and the screen-size range ↩ ↩² ↩³ ↩⁴ ↩⁵

2. Green Coffee Collective — Green Coffee Defects: How to Spot Them and What They Do — green-coffee retailer; confirmed via WebFetch; source of the defect causes and the quaker description ↩ ↩²

3. Keffa Coffee — Green Coffee Defects & Grading Explained — importer’s quality reference; confirmed via WebFetch; sole source of the full-defect equivalence ratios, the 300 g figure and the Grade 1 / Grade 2 tiers ↩ ↩² ↩³ ↩⁴

4. Green Coffee Collective — How the Coffee Grading System Works — confirmed via WebFetch; source of the 350 g / zero-primary / five-secondary rule and the list of national systems covered ↩ ↩² ↩³ ↩⁴

5. Cropster — Master Green Grading: A Coffee Roaster’s Guide — roasting software company’s technical guide; confirmed via WebFetch; source of the 350 g sample, the 10–12% moisture range attributed to the SCA, and the black mat / 4000 K / 1200 lux bench conditions ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

6. Coffee Research Institute — SCAA Green Coffee Classification — archive of the 2004 SCAA classification; confirmed via WebFetch; source of the five-grade ladder, the 300 g counts, the 9–13% moisture tolerance, the quaker limits, the 5% screen tolerance and the screens 14–18 sizing protocol ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

7. FAO — Annex 7: Green Coffee Classification and Grading — UN Food and Agriculture Organization; confirmed via WebFetch; source of the five size grades, the Extra prime / Prime / Superior / Regular classes and the 120-defect ceiling in 300 g ↩ ↩² ↩³ ↩⁴

8. Royal Coffee — Green Coffee Analytics Part III: Visual Defects — green-coffee importer, by Chris Kornman, 10 August 2016; confirmed via WebFetch; source of the intrinsic-vs-foreign split and the stated purpose of each system ↩ ↩² ↩³

9. ICT Coffee — Green Coffee Grading: SHB, EP, Grade 1 for Roasters — green coffee supplier’s guide; confirmed via WebFetch; sole source of the SHB/SHG/HB altitude bands, the EP definition and the screen 15 ≈ 6 mm / screen 18 ≈ 7.2 mm conversions ↩ ↩² ↩³ ↩⁴