A5 is not one grade but two. The letter is the yield grade — an estimate of how much saleable meat a carcass gives up, scored A, B or C. The number is the quality grade, 1 to 5, and it is fixed by the lowest of four separate assessments. So A5 describes a carcass that cuts efficiently and scored 5 on every quality criterion. It is a judgment about a side of beef on a hook — not about the breed, the farm, the feed, or how the piece in front of you will taste.
Who grades it, and where
Grading is carried out by the Japan Meat Grading Association (JMGA), which applies the national beef carcass trading standard. Assessors open the chilled carcass between the sixth and seventh ribs and read the exposed cross-section. Everything that follows — the letter, the number, the marbling score — comes from that single cut face.
The letter: yield grade A, B and C
Yield grade estimates cutability, the proportion of the carcass that becomes saleable cuts. A yield figure is calculated from four measurements: the loin eye area, the thickness of the rib, the thickness of the subcutaneous fat, and the cold half-carcass weight. The result falls into three bands — A is 72 and above, B runs from 69 to just under 72, and C is below 69.
That is the entire content of the letter. Yield grade is an efficiency measure written for the trade, a butcher's arithmetic about how much meat comes off the bone. It carries no information about eating quality. A superb steak can come off a B carcass, and regularly does.
The number: quality grade 1 to 5
The quality grade rests on four criteria, each scored 1 to 5:
- Marbling — the intramuscular fat in the loin
- Meat colour and brightness
- Firmness and texture
- Fat colour, lustre and quality
The rule that matters is this: the overall quality grade is the lowest of the four, not an average. A carcass with flawless marbling, colour and texture but a fat score of 3 is graded 3. One weak criterion caps the whole, which makes the number stricter than it first appears — and makes the leap from 4 to 5 less about marbling alone than most menus imply.
BMS: the marbling scale behind the number
Marbling has its own finer scale, the Beef Marbling Standard, running from 1 to 12 and judged against reference images. It maps onto the marbling criterion as follows:
- BMS 1 — marbling grade 1
- BMS 2 — grade 2
- BMS 3 to 4 — grade 3
- BMS 5 to 7 — grade 4
- BMS 8 to 12 — grade 5
Note the width of that top band. BMS 8 and BMS 12 are both grade 5, and they do not look alike on the plate, let alone eat alike. This is why careful suppliers and serious counters quote the BMS number rather than the letter-and-digit shorthand. "A5, BMS 12" and "A5, BMS 8" describe two quite different pieces of beef. A menu that says only A5 has given you the least precise version of the truth.
What A5 does not tell you
It does not tell you the breed, the strain, or the bloodline. It does not tell you the prefecture, the farm, or the feeding regime, nor the age at which the animal was finished — all of which shape flavour far more than a grade does. It says nothing about the cut, and nothing about what happened after grading: the ageing, the butchery, the hand at the fire.
Grading was designed to price carcasses at auction, consistently and at speed. It was never designed to predict pleasure. Read as a guarantee of deliciousness, A5 is being asked to do work it was not built for.
Wagyu the breed group, Kobe the brand
Wagyu is not a grade and not a place. It names four Japanese cattle breeds — Japanese Black (kuroge washu), Japanese Brown, Japanese Shorthorn and Japanese Polled — and crosses between those four, and nothing else. The Ministry of Agriculture, Forestry and Fisheries puts Japanese Black at over 90 per cent of the wagyu fattened in Japan, which is why the two words are used almost interchangeably — though the other three exist, and eat differently.
Branded beef sits on top of that. Kobe, Matsusaka, Omi, Hida and dozens of regional names are certification schemes with their own rules on lineage, birthplace, rearing and grade. Kobe beef requires Tajima-strain Japanese Black — sired by Hyogo prefectural bulls and raised in Hyogo throughout — slaughtered in the prefecture between 28 and 60 months; the animal must be a heifer that has not calved, or a steer; and the carcass must reach BMS No. 6 or higher, hold a yield grade of A or B and an overall quality grade of 4 or above, and fall within a weight range that tops out at 499.9kg.
Note what those thresholds admit, and what they do not. The quality grade of 4 or above is the strict part, because that grade is the lowest of the four criteria — colour, texture and fat quality all have to hold up, not marbling alone. But BMS 6 sits inside the grade-4 band, and B-yield carcasses qualify. Certified Kobe beef is not all A5, and was never intended to be. Our companion piece on where to eat Kobe beef and wagyu covers the cities and the rooms.
Why a good counter may serve you A4
The practical consequence of extreme marbling is that you cannot eat much of it. Beyond a certain point the fat dominates, the palate closes down after a few bites, and the rest of the meal has nowhere to go. Chefs know this. Many Japanese houses build the regular menu around A4 — often BMS 7 — and hold the highest-marbled beef for a small course or a single slice, because a generous portion of A4 gives more eating than a rich sliver of A5.
You will see the same logic in how the best rooms describe their beef. At Misono in Kobe, the teppanyaki house that holds itself as the birthplace of the format, the offer is Kobe beef alongside A4 and A5 kuroge wagyu — grades presented as options, not a ladder. At Kitchen Hida in Takayama, the argument is ageing: Hida beef held two to four weeks and finished one unchanging way. Neither leads with a grade, because the grade was never the point.
The useful questions at the counter are simpler than the alphabet. Which breed and which brand. Which producer, and which cut. How long it was aged, and how it will be cooked. A house worth the money answers all four without pausing.
If you would like a wagyu meal arranged around those answers rather than around a letter — the right house, the right cut, the right night — our reservation desk can take it from here.