On a menu in London or New York, “A5 Wagyu” is printed as though it were the end of an argument. In Japan it is the beginning of one. The letter and the number come from a public document, the gyū edaniku torihiki kikaku, or beef carcass trading standard, which sets out to three decimal places how a carcass earns each mark.
That document is not written for diners. It was drawn up to make price formation fair at the wholesale market, and it grades every carcass that passes through, whether or not the animal was Wagyu at all. Read it closely and the familiar shorthand starts to come apart: A5 turns out to be a floor rather than a peak, the most famous brand in Japan does not require A5, and the second most famous does not use the grading system in its definition at all.
This article is one way in — a single thread drawn from a much wider story of region, craft, and taste.
A Japanese beef grade is two separate judgments written side by side. The letter is the yield grade: how much saleable meat the carcass gives up for its weight. The number is the meat quality grade. They are decided independently and then recorded together, which produces exactly fifteen possible marks, from A5 down to C1.
The grading is carried out by the Japan Meat Grading Association, a public-interest incorporated association, under a standard it drew up with the approval of the Ministry of Agriculture, Forestry and Fisheries. The association describes its own role in commercial terms, not culinary ones: it grades each carcass individually, from a neutral position, so that trading at the meat wholesale markets and meat centers — over two hundred sites across the country — can run on a single nationwide quality index.
This is the first thing the shorthand loses. The grade is a trading instrument: it tells a buyer what a carcass is worth against the other carcasses on the same morning. Nothing in the standard claims it predicts flavor.
The grid itself is recent. The association publishes a table of every revision the beef standard has been through, and it shows a different animal being rewarded before 1988.
The standard was established in October 1961 with five grades carrying Japanese names — gokujō (superb), jō, chū, nami and off-grade — and it judged outward appearance, symmetry, flesh, fat cover and finish alongside the meat itself, reading the carcass between the fifth and tenth ribs. Crucially, each grade carried a minimum half-carcass weight: 130 kg for the top grade, then 115, 95 and 80. A small carcass could not reach the top grade however good its meat was. In January 1971 a sixth grade, tokusen, was added above gokujō, and the same revision consolidated the fat judgment into a single item and set out marbling thresholds grade by grade, the new top grade demanding the highest band.
In April 1988 the association made what its own table labels a fundamental revision. The named grades were replaced by the fifteen-cell grid; yield became a calculated value with the 72 and 69 thresholds; quality became the lowest of four items; and the three numbered reference scales appeared together, BMS No. 1 to 12, BCS No. 1 to 7, BFS No. 1 to 7. The cut moved to between the sixth and seventh ribs, where it still is.
That revision is the hinge, though not in the way it is usually told. Marbling was not a new concern in 1988: it sat among the quality items from the very first version in 1961, and the 1971 revision had already tied explicit marbling thresholds to each grade. What 1988 removed was the minimum weight. Size stopped being a gate and became a term in an equation where it now counts against you, and marbling gained a numbered twelve-point scale of its own. The alphanumeric shorthand printed on menus worldwide dates only from that revision, and what it replaced was not indifference to marbling but a system that also insisted the carcass be large.
The yield grade has three bands, set against a calculated figure called the yield base value. The published standard puts the thresholds at 72 or above for A, 69 or above but under 72 for B, and under 69 for C. A is defined as a partial-meat yield better than standard, B as standard, C as below standard.
The yield base value is not an impression. It is an equation:
Yield base value = 67.37 + (0.130 × ribeye area in cm²) + (0.667 × thickness of the bara, or belly, in cm) − (0.025 × chilled half-carcass weight in kg) − (0.896 × subcutaneous fat thickness in cm), with 2.049 added for the four beef breeds
Every measurement in that equation comes from one place. The carcass is split into halves and cut open flat between the sixth and seventh ribs, and the grader reads the exposed face. Note the signs: a large ribeye and a thick belly push the number up, while a heavy carcass and a thick jacket of subcutaneous fat pull it down. A large animal is penalized for its size, and outside fat counts against the yield even though inside fat is what the number beside the letter is about.
Two details in the standard rarely survive translation. The first is that intermuscular fat, the fat sitting between the muscles, is measured at the cut face but is explicitly excluded from the equation. It still matters: if it is relatively thick for the carcass weight and ribeye area, the grader may drop the yield grade by one band anyway. The same one-band downgrade is permitted when the round lacks thickness and the balance between forequarter and hindquarter is badly off. A carcass can therefore calculate to an A and be written down to a B on the grader's judgment.
The second is an adjustment that decides a great many letters. For beef-breed carcasses, 2.049 is added to the yield base value before the bands are applied. The standard names the breeds this addition applies to: Japanese Black (Kuroge Washu), Japanese Brown (Akage Washu), Japanese Shorthorn (Nihon Tankaku) and Japanese Polled (Mukaku Washu), together with crosses among those four. The Tajima line that Kobe Beef draws on sits inside the first of them. The formula is tilted in favor of Wagyu, by a published constant, before anyone looks at the meat.
The number comes from four items judged separately: marbling, the color and luster of the lean, the firmness and texture of the meat, and the color, luster and quality of the fat. The first three are read on the cut face between the sixth and seventh ribs: the ribeye together with the two semispinalis muscles above it. The fourth is read elsewhere: on the subcutaneous and intermuscular fat, and on the outer and inner fat of the carcass.
Then comes the rule that does most of the work, and it is the one most often left out. Each of the four items is graded from 5 to 1, and the carcass is given the lowest of the four. A carcass with superb marbling and slightly dull fat takes the grade of its weakest item. There is no averaging and no compensation.
Two of the four items are pinned to reference scales, and both behave in ways a simple “higher is better” reading gets wrong. Lean color is matched against the Beef Color Standard, where grade 5 requires a reading of No. 3 to No. 5, a band with a floor and a ceiling. Meat that is too pale falls out of grade 5, and so does meat that is too dark. Grade 4 widens the window to No. 2 through No. 6, grade 3 to No. 1 through No. 6, grade 2 to No. 1 through No. 7. Fat color is matched against the Beef Fat Standard and works differently: grade 5 accepts No. 1 to No. 4 only, grade 4 up to No. 5, grade 3 up to No. 6, grade 2 up to No. 7. That scale is one-sided, and whiter fat is what the top grade demands.
Defects are handled outside the grade instead of inside it. Where a carcass shows one, the standard appends a separate mark to the grade display: a Japanese syllable standing for multiple muscular hemorrhage, edema, myositis, bruising, excision or other. The grade does not absorb the flaw; it is written next to it.
Marbling is the one item with a number of its own. It is scored against the Beef Marbling Standard, which runs from No. 1 to No. 12. The standard then maps that twelve-point scale onto the five-point scale used for the marbling item, and the mapping is not even:
Five of the twelve steps are collapsed into a single 5. A carcass that just cleared BMS No. 8 and one sitting at BMS No. 12 score identically on marbling, and if their other three items also reach 5, both are written A5. They are not the same meat. A5 is the floor of the top band, not the top of the scale, and the grade alone cannot tell you which of the two you are being sold.
It also explains a persistent invention. Search for Wagyu and you will find A9, A10, even A12 offered as though they were higher grades. They do not exist. The letter can only be A, B or C, and the number can only be 5, 4, 3, 2 or 1: fifteen marks in total, and the standard prints the whole grid. What has been half-remembered is the BMS number. There is a BMS No. 9 and a BMS No. 12, and both of them are graded 5. Written correctly, the meat advertised as “A12” is A5, BMS 12.
This is the practical takeaway for anyone spending serious money. The grade compresses the information; the BMS number restores it. Asking a restaurant or a butcher for the BMS figure, and for the certificate it came from, is a more useful question than asking whether the beef is A5, because within A5 the answer can differ by five whole steps.
The national grade is deliberately blind to origin. It does not know which prefecture the animal came from, who raised it, or for how long. Every regional brand therefore writes a second rulebook on top, and the interesting discovery is that these rulebooks disagree with one another about whether the grade matters at all. Comparing the definitions, instead of the reputations, is where the differences become concrete.
The Kobe Beef Marketing and Distribution Promotion Association sets out a chain that starts long before the grade. Calves of Tajima bloodline are born to designated breeding farms within Hyogo Prefecture, entered in the cattle register and tagged with a ten-digit individual identification number, then raised by the breeder to around nine months. Fattening then continues until the animal is at least 28 months old, and on average about 32, on selected rice straw, corn and barley, and the animal must be slaughtered at a meat center inside the prefecture.
Only then does grading enter. Among those Tajima cattle, only heifers that have never calved and steers qualify, and the association's definition sets out its conditions in numbered clauses. The first is explicit about the grade: it accepts yield grades A and B at quality grade 4 or above. The second adds marbling of BMS No. 6 or above. Certified beef is stamped with the nojigiku crest, the prefectural chrysanthemum.
The world's most famous Japanese beef brand therefore does not require A5. Its floor is a 4, written into its own rulebook, and B is accepted alongside A, so a B4 carcass can carry the crest while an A5 carcass from the wrong prefecture cannot. The marbling clause pulls in the opposite direction at the same moment: since the overall quality grade is the lowest of the four items, a carcass whose marbling reads BMS No. 6 or No. 7 has a marbling item of 4 and can never total a 5. Some Kobe Beef is grade 4 by arithmetic, not by misfortune.
The scarcity is also not where it is usually placed. The association publishes its annual certification counts, and in fiscal 2024 it certified 6,820 head as Kobe Beef against 7,330 certified as Tajima-gyu, noting that the Kobe figure sits inside the Tajima one. More than nine in ten certified Tajima cattle went on to become Kobe Beef. The filter that does the real work is the gate before it: qualifying as Tajima-gyu at all, which takes the bloodline, the prefecture, and an age between 28 and 60 months. We follow the brand's history and the taste it is prized for in a separate guide to Kobe beef.
There is a ceiling as well, which almost never appears in English. The association's definition caps carcass weight at 499.9 kg and sets a floor too, with the band differing by sex: 270 kg to 499.9 kg for females, 300 kg to 499.9 kg for steers. A magnificent but heavy carcass is disqualified on size alone. Where a defect mark is present, the determination is referred to a commissioned member company instead of being made automatically.
Then there is the brand that ignores the grade entirely. The Matsusaka Beef Council's definition has three conditions: the animal must be a Japanese Black heifer that has never calved; it must be registered in the Matsusaka Beef Individual Identification Management System; and its fattening period within the Matsusaka production area, the former twenty-two municipalities, must be both the longest and the final one. A calf must enter the area by twelve months of age, and its movements are restricted to within the area thereafter.
No BMS figure appears. No yield grade, no quality grade, no threshold of any kind. Kobe certifies a carcass; Matsusaka certifies a life. The two brands are not two points on one scale — they are two different ideas about what a name should guarantee, and a Matsusaka carcass may be graded anywhere the standard puts it.
Above the main definition sits a stricter tier, Tokusan Matsusaka Ushi, and its rule is a single number: calves brought in from Hyogo Prefecture and fattened in the production area for 900 days or more. The council puts that tier at about 4 percent of all Matsusaka beef in fiscal 2023. The council calls the result beef that has been “aged while still alive”, since carrying an animal that long costs more and risks more than a conventional finish. Two things follow. The calves come from Hyogo, which is Tajima country — the same bloodline pool Kobe Beef draws on, finished under the opposite rule about where an animal must live. And on the national Geographical Indication register the entry is Tokusan Matsusaka Ushi, registered on 3 March 2017; plain Matsusaka beef does not appear on that register.
One small correction the council makes on its own page is worth carrying to the table. Both matsusaka-ushi and matsusaka-gyū are correct readings, and the council says so explicitly. What is wrong is the matsuzaka pronunciation and the spelling 松坂牛, which appears on a great many signs and menus. Our fuller account of the region and its cooking is in the guide to Matsusaka beef.
Yonezawa sets a third kind of bar — lower than Kobe's, and precise where Matsusaka is silent. Registered on the national Geographical Indication list as entry No. 26, also on 3 March 2017, Yonezawagyu is produced in the Okitama region of Yamagata Prefecture, across the cities of Yonezawa, Nan'yō and Nagai and the towns of Takahata, Kawanishi, Iide, Shirataka and Oguni. The registered particulars call for a Japanese Black heifer that has never calved, at least 33 months old at shipping, graded quality grade 3 or above under the Beef Carcass Trading Standard. The registered particulars add that it trades at roughly 20 percent higher on the market.
The brand exists because of a foreigner, and the record is unusually specific about it. In 1871 the first governor of the newly created Yonezawa prefecture, Uesugi Mochinori, invited an English teacher named Charles Henry Dallas to Kōjōkan, the domain school founded by the ninth lord of Yonezawa, Uesugi Yōzan — to teach English and geography. When his term ended four years later, Dallas took a single cow from the village of Soegawa, in what is now Iide, back with him to the foreign settlement at Yokohama. The people who ate it praised it so warmly that Dallas arranged a contract between a Yonezawa livestock dealer and a Yokohama wholesaler and sold the meat under the name Yonezawa beef. On his encouragement the first butcher's shop in Yonezawa opened in 1875. The boxed meal sold at Yonezawa Station has been on sale since 1899.
Omi reaches back furthest. Shiga Prefecture dates the history to roughly 400 years ago, which places its beginnings inside the Edo period, when eating meat was prohibited. The Hikone domain worked around the prohibition by presenting beef to the shogunal house as a medicinal preparation under the name henpongan; a letter of thanks from the Mito domain to the lord of Hikone survives. After the Meiji opening, Omi merchants began carrying the beef to Yokohama and Tokyo, and the reputation spread from there.
The prefecture ties the brand to the Omi merchants' ethic of sanpō-yoshi: good for the seller, good for the buyer, good for society, and has recently extended the same formula to the animal itself, naming animal welfare explicitly. On the meat, the prefecture is careful about what it claims. Shiga is a long-established rice-growing region, so rice straw has traditionally been used as feed, and the fat has a low melting point and is high in oleic acid. Omi beef was entered on the Geographical Indication register as No. 56 on 15 December 2017. For completeness, the two earliest beef entries on that register are Tajima beef at No. 2 and Kobe Beef at No. 3, both registered on 22 December 2015.
One phrase is worth watching as you read these pages. Shiga's page calls Omi beef one of Japan's three great Wagyu. The national product record for Yonezawa says Yonezawa is often called the same thing. Both statements sit on official documents, and they are not describing the same set of three. Neither document says which three, and the phrase appears on no registry, which is worth remembering when a menu asserts membership.
The most common misreading of a Japanese beef grade is to treat it as a certificate of breed. It is not, and the standard says so in a single line: the grading applies to every carcass regardless of breed, age or sex, with only calves excluded. A dairy animal is graded on the same sheet as a Japanese Black, and the association's own worked examples on its standard page include dairy-breed carcasses receiving B and C letters. “A5” by itself is a statement about a carcass, not about what the animal was.
Where breed does enter is through the 2.049 adjustment, and only there. That addition is reserved for the four beef breeds the standard names: Japanese Black, Japanese Brown, Japanese Shorthorn, Japanese Polled — and crosses among them. Japanese Black, Kuroge Washu, dominates the branded beef in this article: Kobe, Matsusaka and Yonezawa all specify it, or the Tajima line within it. The adjustment does not grade the breed. It moves the yield arithmetic in its favor, then leaves the four quality items to be judged on what is actually on the cut face.
Beyond that, the silences in the standard are worth naming. The grade knows nothing about the farm, the feed, the number of months, or the conditions the animal lived in, every one of which the brand rulebooks above legislate for, precisely because the national grade does not. It is assigned on a chilled carcass at one exposed face, on a market morning, by eye and by measurement. It makes no claim about how the meat will behave in a pan. The comparison with the Western steakhouse tradition is taken up separately in Wagyu compared with Western steak.
Once the structure is clear, three questions do most of the work at a counter. What is the BMS number, since A5 spans five of them. Which brand certificate is attached, since the brand rules and the national grade answer different questions. And, where a brand certificate is produced, what that particular brand actually requires: the floor for Kobe is BMS 6, for Yonezawa it is quality grade 3, and the Matsusaka rulebook does not mention grading at all.
Seeing the machinery itself is a further step, and access to it is layered. The grade stamp and the brand certificate are public, and serious restaurants display them without being asked. One level in, the Tokyo Metropolitan Central Wholesale Market runs a small public gallery at the Shibaura meat market called Oniku no Jōhōkan, the meat information hall, open 10:00 to 18:00 and closed on Saturdays, Sundays, public holidays and over the New Year. Its displays run from the history of the Shibaura abattoir through slaughter and market-trading procedure to carcass grading and cuts — and, in a section the museum does not hide, the history of prejudice and discrimination attached to work with meat in Japan.
Beyond that sits everything the certificates point at and the public cannot simply walk into: the breeding barns, the individual pedigree records, the graders' morning at the rail. That tier exists, and knowing it exists changes how the marks on a menu read.
What the grade cannot reach at all is the part of the animal's life that happens before the rail, which we follow separately in how Wagyu cattle are raised.
The Wagyu ranking is a smaller claim than it appears, made with more precision than it is usually given credit for. Two judgments, fifteen marks, four quality items of which only the weakest counts, and a twelve-point marbling scale flattened into a five-point grade at the last moment. Everything the grade does, it does to a carcass on a market morning.
What it leaves out is where the regions come in, and they do not answer in one voice. Kobe draws its line at BMS 6 with a weight band on either side, Yonezawa at quality grade 3 and 33 months, Matsusaka at a breed, a place and no grade at all. A traveler who knows that much is no longer reading a menu for the highest letter. They are asking which promise is being made — and that is a considerably more interesting question to carry to the table.