United States Grade Standards for Wheat

Grading proceeds in two steps. A lot is first assigned to a class based on kernel characteristics — the standards recognise classes such as Hard Red Winter, Hard Red Spring, Soft Red Winter, Hard White, Soft White, Durum, and Mixed wheat. The lot is then assigned a numerical grade determined by the grading factors, with the lowest-ranking factor governing the outcome.

Because the poorest factor determines the grade, a single defect can cap an otherwise sound lot. "U.S. Sample grade" applies to wheat that does not meet the requirements of the numbered grades, or that carries specified objectionable characteristics.

The standard determines grade from factors measured on a representative sample drawn under official sampling procedures. The principal grading factors include:

• Test weight per bushel — a bulk-density measure used as a general soundness indicator
• Damaged kernels, including heat-damaged kernels
• Foreign material
• Shrunken and broken kernels
• Defects (a combined limit across specified factors)
• Contrasting classes and wheat of other classes

Separately from grade, the standards provide for special grades and for factors such as moisture and protein to be determined and reported. Moisture is central to storability and is routinely measured, but in this standard it is reported rather than being the basis of the numerical grade itself.

A grade is a standardised commercial description of a lot, not a verdict on its overall quality and not a food-safety determination. A lot meeting U.S. No. 2 may still be unsuitable for a particular mill or contract, and buyers routinely specify protein, falling number, or other attributes on top of grade. Conversely, a lower grade does not by itself imply a lot is unsafe.

A grade applies to the lot the sample represents. Official grading depends on prescribed sampling and handling procedures, because a sample that does not represent the lot produces a grade that does not either. Sampling method, sample size, and lot definition are all governed by the official procedures rather than left to the parties.