Beef Grading Scales
The beef grading scale used by the U.S. Department of Agriculture refers to the amount of fat in the beef, though the USDA describes it as "tenderness, juiciness, and flavor." Marbling refers to the level of fat distributed throughout the "lean," or edible meat portion of the beef.

Wagyu beef's quality is so high that it does not fit on the U.S. chart. The Japanese beef grading scale has a range of 1-12, with twelve being the best meat possible. A score of 12 is extremely rare; a good cut of Wagyu beef usually ranks around 10. The chart below compares the USDA scale to the Japanese scale.

USDA Grade   Description   Japanese Score Prime   Top quality beef, with a high degree of marbling (almost 25% fat); usually sold to restaurants and commercial kitchens rather than consumers.   5 – 6 Choice   High quality, with a good degree of marbling (about 20% fat); usually the top grade sold in supermarkets.   2 – 4 Select   Leaner meat because of less marbling (about 17% fat). Sold in supermarkets.   1 – 2

Grading Results
According to anecdotal evidence, approximately 90 percent of F1 production will grade 5, 6 or 7. In other words, 90 percent of the F1's - if fed for 400-450 days - will grade Prime or High Prime. Of course, the final results are highly dependent on variables such as feeding and breeding and no published numbers are available to prove these beliefs. It is possible for 95 percent of Full Blood Wagyu - if fed for 400-450 days - to grade 7, 8, 9, or 10 on the Japanese grading chart. On occasion, Full Blood carcasses will grade 11 or 12. These numbers are off the American grading chart!