GIFSQ Tools · Module 5 — Cereal, Grain, Flour & Milling Technology · Tool 84 of 500
Dockage and foreign material in a grain sample. Enter the total sample mass and the mass of foreign material to get the percentage, the clean grain mass, and the payable weight of a delivered lot.
Try sample values — fills the form with the worked example below.
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Foreign material (%)
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Clean grain (g)
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Payable weight (kg)
Equation: Foreign material % = foreign material mass ÷ total sample mass × 100. Clean grain = total sample mass − foreign material mass. Payable weight = delivered weight × (100 − foreign material %) ÷ 100.
Method: Dockage determination by hand sieving and hand picking, as in the Canadian Grain Commission grading practice for cereals: a representative sample is sieved, the material retained and passing is separated, and foreign material is weighed to 0.01 g.
Assumptions: the sample represents the lot; sieving and picking separate all foreign material; the dockage percentage applies evenly across the delivered lot.
Limitations: a small or unrepresentative sample misstates the lot; very fine dockage can pass with the grain; the payable-weight step is a commercial deduction, not a laboratory result.
Rounding: foreign material to 2 decimal places; clean grain to 2 decimal places; payable weight to 2 decimal places. Intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Dockage determination by hand sieving and hand picking, as in the Canadian Grain Commission grading practice for cereals: a representative sample is sieved, the material retained and passing is separated, and foreign material is weighed to 0.01 g.
Assumptions: the sample represents the lot; sieving and picking separate all foreign material; the dockage percentage applies evenly across the delivered lot.
Limitations: a small or unrepresentative sample misstates the lot; very fine dockage can pass with the grain; the payable-weight step is a commercial deduction, not a laboratory result.
Rounding: foreign material to 2 decimal places; clean grain to 2 decimal places; payable weight to 2 decimal places. Intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: A 1,000 g wheat sample contains 25 g of foreign material. Foreign material = 25 ÷ 1,000 × 100 = 2.50 %; clean grain = 975.00 g. On a 20,000 kg delivery the payable weight = 20,000 × 97.50 ÷ 100 = 19,500.00 kg (500.00 kg dockage deduction).
Enter values above to see results.
Foreign material includes weed seeds, chaff, stones, and other grains. Keep the hand-picked foreign material for the record. Tool 84 of 500 — GIFSQ Tool 84 of 500 — GIFSQ
