Screen sizes

Screen 17 Coffee

Screen 17 rarely travels alone. Understanding why — and knowing the two cases where it does — makes several East African offer sheets easier to read.

Last reviewed July 20262 min read

Quick answer

Screen 17 is a 17/64 inch perforation, approximately 6.75 mm. It is most often encountered as the lower half of a Kenyan AA specification written as "17/18", and as Tanzania’s A grade. Ugandan Robusta trades a screen 17 parcel in its own right.

The measurement

Screen number: 17
Perforation: 17/64 inch = 0.265625 inch
Millimetres: 6.75 mm
Difference from screen 18: 0.40 mm — a narrow step, which is why the two are often combined

Why 17 is usually banded with 18

The gap between consecutive screens is one 64th of an inch — under 0.4 mm. That is a small enough step that separating 17 from 18 produces two thin parcels rather than one useful one, and thin parcels are expensive to mill, store and ship.

Kenya resolves this by writing AA as a 17/18 band, which is why a Kenyan AA screen analysis will show beans across both. Tanzania takes the other approach and keeps A (screen 17) nominally distinct from AA (screen 18+), though in practice A is frequently merged into the AB block rather than sold alone.

Screen 17 across origins
	Kenya	Tanzania	Uganda Robusta
Named grade	Part of AA (17/18)	Grade A	Screen 17
Sold alone?	No	Rarely — usually merged into AB	Yes
Typical role	Volume within the AA block	Bridging size between AA and B	Intermediate sized parcel

Where screen 17 is genuinely useful

As a tight band with 16. A 16/17 specification gives most of the roast-uniformity benefit of an 18 at a materially lower differential.
In Ugandan Robusta, where 17 sits between the premium 18 and the volume 15 and can be the right compromise on price.
As a fallback when a screen 18 requirement cannot be filled from the current crop — worth agreeing in advance rather than discovering at shipment.

Screen-banded enquiries

We can quote against a specific band — 17+, 16/17, 15/16 — rather than only against the origin’s standard grade names.

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Frequently asked questions

How many millimetres is screen 17?

Approximately 6.75 mm — 17 × 0.396875.

Why do Kenyan AA specifications say 17/18?

Because the step between consecutive screens is under 0.4 mm, and separating them would produce two thin parcels instead of one commercially useful block. Kenya bands them; the AA screen analysis therefore shows beans across both.

Is screen 17 lower quality than screen 18?

No. It is a smaller bean width. Both come from the same coffee and the same processing. The price difference reflects the relative scarcity of the larger size class.

Tell us the coffee you need

Lots can be specified by origin, region, process, grade, screen, moisture, defect tolerance, crop year and packaging. Send what you know and we will confirm what each origin realistically supports.