There are a variety of different marbling scales used globally, it is important to understand what scale is being used when reviewing data and buying or selling Wagyu beef. There are three major scales, the USDA marbling scale, the AUS-Meat marbling scale, and the Japanese Beef Marbling Score scale.
The USDA marbling scores consist of four different categories based on the level of marbling. They are from in order of quality from worst to best Standard, Select, Choice, and Prime. Prime is classified as having moderately abundant marbling (12% or greater). Only an estimated 9% of cattle in the USA graded Prime in 2019.
USDA Beef Grading Facts: https://www.beefresearch.org/CMDocs/BeefResearch/Beef%20Grading.pdf
The Australian marbling scale is the AUS-Meat system, a 0 (least) – 9 (most) ranking based on the amount of marbling. The scale typically starts at 1 (1% IMF) and goes to 9 (21% IMF). Carcasses with IMF percentages exceeding 21% are given a further score of 9+. This scale exceeds the USDA scale but still stops where the Japanese BMS scale begins.
AUS-Meat Grading Facts: https://www.ausmeat.com.au/WebDocuments/Chiller_Assessment_Language.pdf
The Japanese marbling scale is the Beef Marbling Score (BMS) system. This system was revised in 2008 and is a 1-12 scale with 1 being worst and 12 the best. Scores 1 and 2 are rare representing animals with little to no marbling. The scale typically begins at 3 (around 21% IMF) and goes to 12 (56% IMF and above). This system also takes into consideration marbling fineness and distribution.
Often confused with a marbling scale is the Japanese quality grade scale, which is based on yield and quality (Fat color, meat color, marbling, and texture). The highest quality grade is A5. To make the A5 grade the carcass must have a yield of 72% or above, a BMS of 8-12, meat color No. 3 – 5, fat color No. 1 – 4, and a very fine texture.
Japanese BMS Guide: https://wagyu.org/uploads/page/JMGA%20Beef%20Marbling%20Standard(2008).pdf
Japanese Quality Grade Guide: