A5 vs MB9+: Japanese and Australian Wagyu Grading, Decoded

“A5” and “MB9+” turn up on the same Singapore menus, often a few lines apart, and they are usually read as two ways of saying “very marbled”. They are not. One is a Japanese carcass grade made of two separate judgements; the other is a single Australian measurement of one thing. Neither converts neatly into the other, and the reasons why are the most useful thing to know before you pay for either.

We have already explained the Australian side in detail — what MB4+ and MB9+ actually mean, including why “MB” is a marbling score rather than a grade. This post is about the Japanese system, and about what happens when you put the two side by side.

A5 is two grades, not one

In Japan, beef carcasses are graded to a standard set by the Japan Meat Grading Association. The label has two parts, and they measure completely different things.

The letter is the yield grade. It describes how much usable meat the carcass gives relative to its dressed weight. According to the Japan Meat Information Service Center, A means a yield of 72 or more, B means 69 or more, and C means below 69. The yield score comes from a formula built on measurements such as the area of the ribeye, the thickness of the short ribs, the weight of the half carcass and the depth of fat under the skin.

That letter is about the carcass as a commercial object. It tells you nothing about how the steak will eat. An “A” is good news for the wholesaler; for the diner it is close to irrelevant.

The number is the quality grade, from 5 (highest) to 1. It is decided on four criteria: marbling, meat colour and brightness, firmness and texture, and fat colour, lustre and quality. Put together, that gives fifteen possible labels, A1 to C5, of which A5 is the top.

The weakest of four

The detail that changes how you read the number: the quality grade is not an average. The Wagyu Authentic explainer site states that the lowest of the four criterion grades becomes the carcass’s meat quality grade. A carcass with spectacular marbling but only grade-4 fat colour is a 4, not a 5.

So a 5 is a claim about all four things at once — the fat, the colour, the texture and the marbling have each cleared the top bar. That is a genuinely demanding standard, and it is the best argument for the label.

But “5” is a wide band

Marbling inside that system is scored on the Beef Marbling Standard, BMS, from No.1 to No.12. The mapping from BMS to quality grade, as the Japan Meat Information Service Center publishes it, is:

• Grade 5: BMS No.8 to No.12
• Grade 4: BMS No.5 to No.7
• Grade 3: BMS No.3 to No.4
• Grade 2: BMS No.2
• Grade 1: BMS No.1

Grade 5 spans five marbling steps. Two steaks can both be sold as A5 and sit four BMS points apart. If the marbling is what you are paying for, the BMS number is the more precise thing to ask for — and a seller of Japanese beef can often tell you it.

MB9+ is one measurement

The Australian number works differently. AUS-MEAT’s marble score runs from 0 (nil) to 9 (abundant), and Meat & Livestock Australia is explicit that it is assessed on the amount of marbling in the eye muscle. Colour, fat colour and the rest are recorded as separate scores rather than folded into one grade. Scores beyond the top of the scale are written as 9+ — Blackmore, the producer of our karubi, says as much on its own site.

Australia also has a finer scale: Meat Standards Australia’s marble score, from 100 to 1190 in steps of 10, which judges distribution as well as amount. Most menus do not print it.

Why the two do not convert

Online you will find tables that line up AUS-MEAT 9+ against BMS 9 to 12, or declare an MB9+ steak “equivalent to A5”. Be wary of them, for three reasons:

• They measure different things. A5 includes a yield grade and three non-marbling criteria; MB9+ is marbling alone. An “equivalent” can at best compare one of A5’s four quality inputs with the whole of MB9+.
• They look in different places. Japanese grading is done on a cut between the 6th and 7th ribs of the left carcass, per Wagyu Authentic. AUS-MEAT marbling is usually assessed between the 10th and 11th or 12th and 13th ribs, per Meat & Livestock Australia. Marbling is not uniform along the animal, so two scorers at different ribs are not reading the same meat.
• They use different reference scales. Twelve steps against ten, each with its own reference standards. Neither body publishes an official conversion to the other that we could find.

The honest summary: a high BMS and a high AUS-MEAT marble score both mean a lot of intramuscular fat, and that is where the comparison should stop.

What either number does not tell you

Neither grade tells you the breed with any precision (a grade describes a carcass, not a pedigree), the cut (both are measured at the rib, whatever you are actually eating), the diet or the age at slaughter. For those you need the producer’s own description. That is why our menu prints more than the score: “200g full blood wagyu short ribs, 600-day grain-fed” for the karubi, “300g grain-finished” for the ribeye.

Ours, for the record

Both of our beef dishes are Australian and carry AUS-MEAT marble scores: an Angus Pure Southern Australian ribeye MB4+ and a Blackmore full blood wagyu karubi MB9+, both with truffle ponzu jus. Neither is A5, and neither could be — A5 is a grade given to Japanese carcasses in Japan. We would rather tell you that than let an MB9+ borrow a Japanese label it was never graded under.

What we can say is that they are two very different eats: the ribeye is the leaner, beefier plate, and the karubi is 200g of heavily marbled short rib. The story of that cut and its name is in what karubi actually is, and our wagyu in Singapore guide puts both next to four other ways of eating wagyu in the city, including restaurants that do serve Japanese A4 and A5. Both dishes sit in the Biggies section of our menu, which prints no prices; you can book a table at 29 Hamilton Road, Tuesday to Sunday from 5pm. For the wider picture of Japanese food in Singapore, start with our full guide.

Sources

• Japan Meat Information Service Center, “About Meat — Beef Grading” (yield thresholds; BMS-to-grade mapping; BMS, BCS and BFS).
• Wagyu Authentic, “Meat Grading System” (6th/7th rib grading site; lowest criterion sets the grade; yield formula).
• Wikipedia, “Wagyu” (fifteen combinations, A1 to C5).
• Meat & Livestock Australia, “AUS-MEAT marbling” (0–9 scale; amount only; quartering site; MSA as a finer scale).
• Blackmore Wagyu, “Our Wagyu” (AUS-MEAT grading; 9+).
• Our own Hamilton Road food menu (both beef lines, verbatim).