Grading reference

East African Coffee Grades

Six origins, six grading systems, and no reliable mapping between them. This page sets the systems side by side so an offer sheet from one origin can be read against another.

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A grade is contract language. It tells you how a parcel was prepared and separated, and it lets two parties agree on a deliverable. What it does not do — outside Ethiopia — is tell you how the coffee tastes.

Read this before comparing grades

Grades describe preparation, bean size and defect tolerance. Outside Ethiopia’s classification, which includes a cup component, a grade designation does not by itself predict cup quality — confirm every parcel on the sample.

Side by side

What each system separates on

The systems are not variants of one another. They separate coffee on different properties, which is why the designations do not translate.

Grading systems compared
Origin	Separates on	Designations	Cup included?
Tanzania	Bean size (screen), then density	AA, A, AB, B, C, PB, E, TT, UG	No
Kenya	Bean size (screen), then density	E, AA, AB, PB, C, TT, T, MH/ML	No
Uganda	Screen and defect specification; trade designations for Arabica	Screen 18/17/15/14/12, FAQ, Bugisu AA/A/B/PB, WUGAR, DRUGAR	No
Ethiopia	Raw defect count combined with a cup evaluation	Grades 1–5 for export; Q1/Q2 used in trade for specialty	Yes — the only one in the region
Rwanda	Defect count and screen	Grade 1, Grade 2, plus explicit screen bands	No
Burundi	Defect count and screen	Grade A, Grade B, plus explicit screen bands	No

Follow any origin for the full system, including what each designation means at that origin and how to write it into a contract.

The traps this table is meant to prevent

Burundian Grade A is not Kenyan AA. One is the top class of a two-tier defect-and-screen system; the other is a size separation inside a seven-grade ladder.
Ethiopian Grade 3 washed is not Ethiopian Grade 3 natural. The defect allowances differ by preparation, so the number alone is incomplete. Always state the preparation with the grade.
Ugandan FAQ is not a fixed standard. Fair Average Quality is contracted against a stated defect and moisture basis that varies by crop and cleaning line. Confirm the basis in writing.
Kenyan MH/ML is not a natural. Mbuni is dried whole cherry that generally includes over-ripes, unders and ground-collected fruit — a different product from a deliberately produced natural, and it should be specified separately.
TT is a density grade, not a size grade. In both Kenya and Tanzania it is what a gravity table lifts off the AA/AB run. Same size, lower density, and it usually cups flatter.

Fundamentals

How a grade is made, and what it leaves out

What a grade actually describes

Grading happens at the dry mill, after hulling. The coffee passes through a sequence of separations, and the grade names the fraction that comes out of a particular step. Three physical properties do almost all of the work.

1Size. Beans are passed over perforated screens whose hole diameters are measured in 64ths of an inch. A parcel “retained on screen 18” is one whose beans will not fall through an 18/64 inch hole. This produces AA, A, AB, B and C in Kenya and Tanzania, and the numbered screens used for Ugandan Robusta — see coffee screen sizes.
2Density. A gravity table or pneumatic separator lifts lighter beans out of a size fraction. The lighter stream becomes its own grade — TT in Kenya and Tanzania — while the heavy stream stays in the main run.
3Shape. Peaberries are round rather than flat-faced and are separated on slotted screens, becoming PB. This is a shape separation and says nothing about quality.

Hulling — parchment or dried cherry removed
Pre-cleaning — stones, husk and foreign matter
Screen separation by bean width
Density separation on the gravity table
Colour sorting, optical and manual
Grade assembly and bagging

The dry-mill sequence a grade designation comes out of.

Defect counting sits alongside these mechanical separations. A defined sample — commonly 300 g of green coffee — is picked over by hand, and each physical defect is weighted before being converted into “full defects”. Several partial black beans make one full defect; one full black bean makes one on its own. Origins differ in their weighting tables, which is one reason defect counts are not directly comparable across countries — see green coffee defects.

What a grade does not describe

Outside Ethiopia, a grade designation contains no sensory information at all. A Kenya AA is a large-bean separation from a particular factory’s outturn; whether it cups well depends on the cherry, the fermentation, the drying and the storage — none of which the screen measures.

This matters commercially. A buyer who specifies “Kenya AA” and nothing else has specified bean size and is paying the premium the AA designation attracts, without specifying the thing they actually want. In many Kenyan offer lists the AB from the same factory is the better purchase, because the price difference between AA and AB is larger than the cup difference. Use the grade to define the physical deliverable, and the approved sample to define the cup. Both belong in the contract.

Preparation: the term underneath the grade

“Preparation” describes how thoroughly a parcel has been cleaned and sorted, independent of its size class. European and American Preparation are the conventions most often cited, and they set different defect ceilings. East African contracts more often state the defect tolerance explicitly than rely on the shorthand, which is the safer approach — the shorthand means slightly different things to different mills.

State the sample size the defect count is drawn on (300 g is the usual basis).
State whether the count is of full defects or of physical pieces — they are not the same number.
State whether a colour-sorter pass is included, and how many passes.
State the maximum foreign matter, and whether stones are counted separately.

Writing a specification that works

Minimum workable specification

Origin and region: Country plus the growing area or, better, the station or factory
Species and process: Arabica or Robusta; washed, natural or honey
Grade: The origin’s own designation
Screen: Retention screen plus the permitted percentage passing
Defects: Maximum full defects per 300 g, and the counting basis
Moisture: Target range and the measurement method
Crop year: Explicit, not “current crop”
Cup: Approved sample, or a described profile with a score floor
Packaging: Bag type, fill weight and liner

The full field list, with a worked example, is in how to specify green coffee.

Size grades

Where the size grades sit against the screen

Most East African grade ladders are screen ladders with letters on them. Plotting them together shows how the origins line up — and where they genuinely do not.

Screen number

Kenya

Tanzania

Uganda Robusta

Scr 12

Scr 14

Scr 15

Scr 17

Scr 18

Rwanda

Grade 2

Grade 1

Burundi

Grade B

Grade A

Kenyan and Tanzanian size grades occupy the same screen ladder but cut it differently — Kenyan AB spans screens 15–16 while Tanzanian AB combines the A and B separations, and Kenyan AA starts a screen lower than Tanzanian AA. Ugandan Robusta is quoted as the screen itself rather than a letter. Rwandan and Burundian grades are defect classes with a screen floor rather than size bands, which is why they read as wide bars: a Grade 1 parcel is screen 15 and above, not a screen 15–16 separation.

Bands show where each designation normally sits. Preparation varies by mill and by contract, and peaberry is separated on its own slotted-screen run and is not plotted here. Position on this chart says nothing about cup quality.

Screen number to aperture
Screen	Aperture	Approx. mm	Where it appears
Screen 20	20/64"	7.94	Above the normal commercial run. Encountered when separating elephant and conjoined beans.
Screen 19	19/64"	7.54	Used as the upper bound of an AA separation when a mill wants to strip out oversized and malformed beans.
Screen 18	18/64"	7.14	The reference large-bean screen across East Africa. Defines AA in Kenya and Tanzania and the largest routinely traded Ugandan Robusta parcel.
Screen 17	17/64"	6.75	The second half of most AA specifications (17/18) and a grade in its own right in Tanzania. Frequently quoted as "screen 17 up".
Screen 16	16/64"	6.35	The upper half of the AB block, and the most common tightened screen request on Rwandan and Burundian washed lots.
Screen 15	15/64"	5.95	The practical floor for most specialty preparations and the volume workhorse of Ugandan Robusta.
Screen 14	14/64"	5.56	Smaller commercial separations. Below this point, size stops being a useful proxy for anything in a specialty context.
Screen 13	13/64"	5.16	Small commercial Robusta and the lower peaberry separations.
Screen 12	12/64"	4.76	The smallest screen in routine commercial use, mostly for soluble-bound Robusta and by-product parcels.

Screen numbers are the aperture in sixty-fourths of an inch. A screen 18 hole is 18/64 in ≈ 7.14 mm. See screen sizes for retention tolerances and the interactive explorer.

By origin

Each system in full

Every origin page covers the complete grade set, what each designation encodes, and the contract language that goes with it.

Questions

Grading questions buyers actually ask

Does AA mean the same thing in Kenya and Tanzania?

Roughly, but not exactly. Both use AA for the largest flat-bean separation, and both are size classes rather than quality classes. The screen boundaries differ slightly — Kenyan AA is screen 17/18, Tanzanian AA is screen 18 and above — and they sit within differently shaped ladders. Never assume a grade transfers between origins without checking the screen.

Which East African grade includes cup quality?

Only Ethiopia. Its grades combine a physical defect assessment with a cup evaluation — export coffee is graded 1 to 5 — which is why an Ethiopian grade carries more information than a Kenyan or Tanzanian one. Everywhere else in the region the grade is purely physical: size, density or defect count.

Is a higher grade always better coffee?

No. Outside Ethiopia the grade describes preparation and bean size, not flavour. A well-separated Kenyan AB from a good factory routinely cups above a poorly separated AA from a weaker one. Use the grade to specify what you will physically receive, and the cup to decide whether you want it.

Why do Uganda and Ethiopia not use letter grades like Kenya?

Because their coffee is traded on different properties. Ugandan Robusta is sold principally on screen size and defect specification, so the screen number is the grade. Ethiopian coffee is classified on defect count plus cup, so a numeric scale carries it. Letter ladders like Kenya’s and Tanzania’s suit an auction system separating a washed Arabica outturn into size fractions.

What should a contract say if the grade is not enough?

State the grade, then state the screen retention with the permitted percentage passing, the maximum full defects per 300 g and the counting basis, the moisture range with the measurement method, the crop year, and the approved sample. The grade is shorthand for a preparation; those fields are the actual deliverable.

Are coffee grades standardised internationally?

No. Each producing country runs its own system through its own authority, and the same letter can mean different things in different places. Tanzanian AA and Kenyan AA are both large-bean separations but sit inside different grade ladders with different neighbouring classes. Always read a grade in the context of its origin.

What is the difference between a grade and a preparation?

The grade names the separation — the size or density fraction. The preparation describes how thoroughly the parcel has been cleaned of defects and foreign matter. Two lots can share a grade and differ substantially in preparation, which is why the defect tolerance belongs in the contract explicitly.

Which East African grade suits a commercial blend?

It depends on what the blend needs. For Arabica volume with consistent supply, the AB block in Kenya and Tanzania is usually the most practical. For Robusta, Ugandan screen 15 is the volume grade and screen 18 is specified when bean size matters to the roast or to a visual match. The right answer follows from the roast profile and the price basis, not from the grade ladder.