US FDA Food Labeling Regulations (21 CFR Part 101) 101.9-SERV: Serving size based on the Reference Amounts Customarily Consumed (101.12) expressed in common household measures with the metric equivalent, servings per container and the discrete unit rules (101.9(b), 101.12)

What does 101.9-SERV require?

The serving size declared on the label must be derived from the Reference Amount Customarily Consumed (RACC) for the product category in the 101.12(b) tables, expressed in a common household measure (cup, tablespoon, piece, slice, fraction) closest to the RACC, followed by the metric amount in grams or milliliters, with the rules for discrete units (one unit if it weighs at least 50 percent of the RACC, two units if each weighs less than 50 percent but combined are between 67 and 200 percent, and so on), for large discrete units labeled as a fractional slice, and for products with less than 200 percent of the RACC labeled as one serving. Servings per container is declared as the number of servings in the package rounded as 101.9(b)(8) requires, with 'about' used for fractional results. Foods for infants and children under four use the separate RACC table.