Kenya Coffee Grades

The Kenyan grade ladder

Why size does not determine quality

There is a real physical difference: larger beans have a lower surface-area-to-mass ratio and therefore absorb heat slightly differently in the roaster. Roasters running tight profiles on single origins may genuinely prefer the size uniformity of an AA. That is a roasting argument, not a quality argument, and it is worth paying for only when it applies.

The practical consequence: when reading a Kenyan offer list, compare the AB and AA from the same factory on the cupping table before assuming the AA is the better buy.

Factories, outturns and what makes Kenyan traceability unusual

Kenyan smallholders deliver cherry to a wet mill — called a factory — operated by their cooperative society. The factory processes and dries the parchment, then sends it to a dry mill, where it is milled as an identified batch called an outturn. Both the factory name and the outturn number follow the coffee through to sale.

This is why Kenyan lots are quoted as, for example, a named factory’s AA from a specific outturn. It gives an unusually precise unit of identity: the coffee of a defined group of farmers, processed together, milled together. When you approve a Kenyan sample you are approving something quite tightly defined.

• Factory — the wet mill where cherry is pulped, fermented, washed and dried.
• Outturn — the identified milling batch at the dry mill; the number that traces the lot.
• Society — the cooperative that owns one or more factories.
• Estate — privately owned farms that process their own cherry and sell under their own name.

Mbuni: Kenya’s naturals, and why they are separate

Mbuni is Kenyan coffee dried as whole cherry rather than pulped. Historically it has been the destination for over-ripes, unders, strip-picked fruit and cherry collected off the ground, which is why it trades at a substantial discount and is graded only by density — MH (heavy) and ML (light).

That is distinct from a deliberately produced Kenyan natural, where ripe cherry is selected specifically for dry processing on raised beds. These are increasingly available and should be specified as such, not ordered as Mbuni. Two different products, two different prices.

The Kenyan trading system

A large share of Kenyan coffee is sold through weekly auctions at the Nairobi Coffee Exchange, with lots catalogued by factory, grade and outturn and bought against pre-auction samples. Direct sales operate alongside the auction. Since the Coffee Act 2026 came into force on 27 March 2026, the sector is regulated by the re-established Coffee Board of Kenya, and the Act recognises auction, direct sales subject to quality checks and price benchmarking, and international exchanges as sales routes. Grower payments run through a central settlement system. Which route applies affects timing, sample flow and documentation, so establish it at the outset of a purchase.

The Act did not expressly repeal the earlier coffee regulations, and how the two fit together was not settled in the sources checked in September 2026 — so confirm the licensing and documentation that apply to a given contract.