Screen sizes

Screen 15 Coffee

Screen 15 does more commercial work than any other screen number in East Africa. It carries most of the Robusta volume, sets the floor for Great Lakes washed Arabica, and forms the lower half of the AB block.

Last reviewed July 20262 min read

Quick answer

Screen 15 is a 15/64 inch perforation, approximately 5.95 mm. It is the volume workhorse of Ugandan Robusta and the practical screen floor for most specialty preparations in Rwanda, Burundi and the Kenyan AB block. Below screen 15, size stops being a useful specification in a specialty context.

The measurement

Screen number: 15
Perforation: 15/64 inch = 0.234375 inch
Millimetres: 5.95 mm
Role: Volume grade in Ugandan Robusta; specialty floor in Rwanda, Burundi and Kenya AB

The Ugandan Robusta volume grade

Ugandan Robusta Screen 15 is the single most traded East African Robusta specification. It balances availability against price: there is enough of it in any normal crop to support multi-container programmes, and it does not carry the scarcity differential that screen 18 does.

Widely used in commercial roast-and-ground blends where Robusta contributes body and crema.
The default input for much soluble production, where bean size matters less than yield and consistency.
Supported by Uganda’s two harvest cycles, so it is rarely out of the market — see the Uganda crop calendar.
Contracted with an explicit defect basis and moisture ceiling, because the screen alone does not constrain either.

The specialty floor

For washed Arabica from Rwanda, Burundi and the Kenyan AB block, screen 15 is the level below which most preparations stop. That is a practical convention rather than a quality threshold — it reflects where mills draw the line between the main run and the smaller separations.

It is worth being clear about what that does and does not imply. Beans below screen 15 are not defective. They are smaller, they are separated out, and they are sold into different channels. Some very good coffee ends up in the small screens, particularly from high-altitude stations where the whole size distribution runs tight.

Screen floors are commercial conventions

A screen 15 floor is a milling and marketing decision, not a statement about the quality of what falls through. Where an origin offers a well-cupping small-screen separation at a sensible price, it can be excellent value — provided the roast profile accommodates the size.

Specifying screen 15

A workable screen 15 clause

Screen: Retained on screen 15, maximum X% passing
Defects: Maximum full defects per 300 g; black and broken stated separately for Robusta
Moisture: Ceiling plus method — Robusta commonly contracts around 12–13%
Foreign matter: Maximum, with stones counted separately
Crop year: Explicit
Packaging: 60 kg jute standard; bulk-lined containers common for Robusta volume

Screen 15 programmes

Multi-container Ugandan Robusta screen 15 is contracted on a programme basis. Tell us the annual volume and shipment pattern and we will quote against it.

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Frequently asked questions

How many millimetres is screen 15?

Approximately 5.95 mm — 15 × 0.396875.

Why is Ugandan Robusta screen 15 so widely traded?

Because it sits at the point where availability and price meet. There is enough of it in a normal crop to support continuous programmes, and it avoids the scarcity differential of screen 18. Uganda’s two harvest cycles keep it available for most of the year.

Is coffee below screen 15 bad?

No. It is smaller. Screen floors are milling and marketing conventions, not quality thresholds. Small-screen separations from high-altitude origins can cup well and be good value, provided the roast profile suits the size.

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.