Tool·Lifes /Meat Atlas

Everything About Meat

From beef primals to tuna sashimi — anatomy charts, marbling grades and doneness temperatures. Click any cut on the chart to open its story.

The chart is the navigation

Hover a cut for a summary, click to open its page — local names, dishes it suits, recommended doneness and how to pick it at the counter.

Beef Primals TOOL-LIFES / MEAT ATLAS
CHUCKChuck RIBRibeye LOINStriploin SIRLOINSirloin ROUNDRound BRISKETBrisket PLATEShort plate FLANKFlank ShankShank HEADHead & cheek Oxtail
FIG. 1 — BOS TAURUS / PRIMAL DIVISIONtool-lifes.com/meat

Marbling is not something you explain in words

The BMS 1–9 scale, drawn rather than described. Japanese A5, Korean 1++, USDA Prime and Australian MSA all sit on this one axis, so grades from different countries can finally be compared by eye.

Doneness is a colour, not a guess

Drag the slider and the cross-section repaints along the real myoglobin curve. Core temperature and resting time move with it.

57 Medium rareRest 3 min
46°C52°C57°C63°C69°C77°C

One axis ties the whole atlas together

Myoglobin shifts with oxygen and heat: deep purple-red when deoxygenated, bright cherry when oxygenated, grey-brown once fully cooked. Those three points are this atlas's entire palette — and the shared visual language of the freshness, doneness and ageing pages.

Temperatures are guidance for whole-muscle cuts. Ground meat and poultry need 71°C / 160°F throughout.

Raw fish needs its own axis

The way a single tuna divides into otoro, chutoro and akami follows a different logic from beef butchery. Fish are modelled on fat content and position rather than muscle group.

Bluefin Tuna Cuts TOOL-LIFES / MEAT ATLAS
Kama Akami Otoro Chutoro Tail belly
FIG. 2 — THUNNUS / CUTTING DIVISIONtool-lifes.com/meat

All cuts

→Chuck→Ribeye→Striploin→Sirloin→Round→Brisket→Short plate→Flank→Shank→Head & cheek→Oxtail→Kama→Akami→Otoro→Chutoro→Tail belly

Common questions

Which beef cut is the most tender?
Among the primals on this chart, the ribeye and striploin are the most tender, because they come from muscles along the spine that barely work during the animal's life. Tenderness tracks workload: the harder a muscle works, the more connective tissue it builds. That is why shank and brisket are the toughest raw — and the most rewarding after long cooking.
What does the marbling grade actually measure?
Marbling grades measure intramuscular fat — the fat inside the muscle rather than the layer around it. Japan's BMS runs 1 to 12, Korea grades 1++ down to 3, and the USDA uses Prime, Choice and Select. They are scored on different scales but they are all looking at the same thing, which is why they can be laid on a single axis.
What core temperature should steak be cooked to?
Roughly 52°C for rare, 57°C for medium rare, 63°C for medium and 71°C and above for well done. These figures apply to whole-muscle cuts. Ground meat and poultry must reach 71°C throughout, because grinding spreads surface bacteria into the interior.
Why does meat need to rest after cooking?
Heat drives moisture towards the centre of the cut and tightens the muscle fibres. Resting lets both settle, so the juice redistributes instead of running out onto the board when you cut. Two to five minutes is enough for a steak; larger roasts need longer.
What is the difference between otoro and chutoro?
Both come from the belly of the tuna, and the difference is fat content and position. Otoro is the forward belly and the fattiest part of the fish; chutoro sits further back and between the belly and the loin, balancing fat against the leaner flavour of akami. Otoro is richer, chutoro is easier to keep eating.
Why does slicing against the grain make meat more tender?
Muscle is built from long fibre bundles. Cutting across them leaves very short fibres on the plate, so your teeth have far less to break down. On a coarse-grained cut like flank the difference is dramatic — the same piece can feel chewy or tender depending only on the angle of the knife.