Chickpea calibration describes how large the individual seeds are. Two conventions coexist in the trade and they are not interchangeable, which is the single most common cause of dispute on a chickpea contract.
The two conventions
The first convention is count per unit weight: the number of whole seeds contained in a fixed mass, usually expressed per 100 g or per ounce. A lower count means larger seeds. This is the convention used most often for kabuli chickpeas traded into Mediterranean and Middle Eastern markets, and it is the one buyers of premium whole chickpeas for retail packing tend to specify.
The second convention is screen size: the diameter of the round-hole sieve aperture through which the seed will or will not pass, quoted in millimetres. Graders run the lot over a stack of test sieves built to the dimensional series in ISO-referenced sieve specifications, and report the mass fraction retained on each deck. A lot described as a given millimetre grade normally means that a stated minimum percentage of the mass sits above that aperture, not that every seed does.
Why the two do not translate cleanly
Count per unit weight is a function of both seed diameter and seed density. Two lots with identical screen distributions can return different counts if one has a higher specific weight, thinner seed coat or lower moisture content. Converting between the conventions with a rule of thumb is how contracts end up in arbitration. The safe practice is to specify one convention as the contractual basis and quote the other as indicative only.
What buyers actually specify
- Primary calibration stated in one convention, with the sieve series or count basis named explicitly
- Tolerance below grade, expressed as a maximum mass percentage of undersize seed
- Uniformity, sometimes as a maximum spread between the largest and smallest retained fractions
- Splits, broken and shrivelled seed, which are counted separately from calibration but affect the visual impression of a grade
Why calibration drives end use
Large-calibre kabuli seed is bought for retail dry packing, canning and the whole-seed salad and mezze trade, where visible size is part of the product. Mid-calibre seed goes to hummus and paste manufacture, where the seed is cooked and milled and size matters only through cooking uniformity. Small-calibre and off-grade seed feeds pulse flour and snack extrusion lines. Because each calibration band has a different demand base, the yield split of a harvest matters more to a chickpea processor than the total tonnage.
Cooking behaviour also tracks size. Larger seed has a lower surface-to-volume ratio and hydrates more slowly, so a mixed-calibre lot cooks unevenly. Food-service buyers therefore treat calibration uniformity as a process specification, not a cosmetic one. See the chickpeas product record for the calibration bands typically offered from Ukrainian origin, and the pulse cleaning, sorting and grading guide for how the sizing equipment works.