Buyer Guides
Understanding Indonesian Coffee Grades Before You Place an Order
Grade 1, screen size, defect count and processing method all move the price of a coffee lot. Here is what each term actually means on an Indonesian contract.
If you are buying Indonesian coffee for the first time, the grading vocabulary can look arbitrary. It is not. Each term on the contract corresponds to a specific, measurable property, and knowing which ones matter for your roast profile is the difference between a lot that performs and one that disappoints.
Grade 1 is a defect count, not a quality rating
Indonesian green coffee is graded by the number of defects found in a 300 gram sample. Grade 1 allows a maximum of 11 defects; Grade 2 allows 12 to 25; the scale continues down to Grade 6. A defect is a black bean, a sour bean, a stone, a piece of husk or a severe insect-damaged bean, each weighted differently.
What this means in practice: Grade 1 tells you the lot is physically clean. It does not tell you how it cups. Two Grade 1 lots from the same region can score five points apart. If cup quality matters to you, ask for a cupping score alongside the grade, and always request a pre-shipment sample.
Screen size affects roast consistency
Screen size is measured in 1/64th of an inch. Screen 16 means the beans passed over a sieve with 16/64 inch holes. Common Indonesian Arabica offers are screen 16 up and 18 up; Robusta is usually screen 13 up.
Larger, more uniform beans roast more evenly, which matters most if you are running a fast-turnaround commercial roast. If you are roasting in small batches with careful profiling, a slightly smaller screen size in exchange for a better cup is often the right trade.
Wet-hulled processing is what makes Sumatra taste like Sumatra
Giling basah, or wet-hulling, is a processing method used almost exclusively in Sumatra. The parchment is removed at a much higher moisture content than in conventional washed processing — around 30 to 35% rather than 11 to 12%. The bean is then dried in its exposed state.
The result is the deep body, low acidity and earthy, cedar-and-herb character that defines Sumatran coffee. It also produces the distinctive blue-green colour of the raw bean. If a supplier offers you a “washed Sumatra” that cups bright and clean, they are either mislabelling it or it is not from the traditional growing areas.
Moisture content is the specification to police
Everything else on the contract is about quality. Moisture is about risk. Above roughly 12.5%, coffee becomes vulnerable to mould in transit, particularly in a container crossing the equator. Below about 10%, the bean has been over-dried and will lose sweetness and age faster.
Ask for moisture to be verified at three points: at intake, after drying, and at the moment of container stuffing. A supplier who only tests once is showing you how much attention the rest of the lot receives.
Questions worth asking any Indonesian supplier
- Which specific cooperative or region is this lot from, and can you show the harvest date?
- What is the moisture reading at stuffing, not at intake?
- Is the container lined with GrainPro or vacuum packaging?
- Can you send a 300 g pre-shipment sample from the actual lot, not a type sample?
- Which certifications apply — organic, Rainforest Alliance, Fair Trade?
A supplier who answers all five without hesitation is a supplier worth shipping with.
Looking for Indonesian green coffee? We supply Grade 1 Arabica and Robusta from Gayo, Toraja, Kintamani, Java and Lampung, with pre-shipment samples on every contract. Request a quotation and tell us your target profile.