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Commercial classes of dry beans are diverse and distinguished by seed size and shape, and seed coat color. The physical characteristics of dry beans are presented in ssss1. Seed size is expressed in various formats, depending on convention and practice. These include: (1) grams per hundred seeds, (2) seed counts per 100 grams, (3) seeds per pound, and (4) standard US sieve size characterization.

Expressing seed size as weight per unit is common among plant breeders and seed specialists; desired seed size is defined by the commercial market class. Thus, grams per 100 seed count will vary from 48–56 g/100 seed for the large‐seeded kidney bean to 15–16 g/100 seed for the small white classes. Navy bean seeds weighing 17–19 g/100 seeds are common. Alternatively, black beans are generally selected to a size of about 500–550 seeds/100 g.

Expressing seed size as the number of seeds per pound is common within the agricultural sector of the dry bean industry and is typically used to establish seed planting rates required for desired plant densities (plant population per acre). The approximate number of seeds per pound for specific dry bean market classes is provided in ssss1.