What Cut of Beef is Prime Rib?

Prime rib is a legendary roast that stars on menus and holiday tables. But despite its fame, there’s often confusion about exactly where this celebrated cut comes from on the cow. Keep reading to learn what primal cut prime rib is sourced from, how it’s prepared, and what makes it so special.

What is Prime Rib?

Prime rib refers to a standing rib roast cut from the primal rib section of beef. It consists of ribs 6 through 12 of the cow, and includes the impressive “eye” muscle, also known as the ribeye.

A whole prime rib roast includes the bones and a large portion of the prime ribeye – it’s essentially a rack of ribs still attached to the ribeye muscle. Prime rib roasts can include up to seven ribs.

When sliced into individual portions, the choicest cut adjacent to the ribs is known as a ribeye steak. The ribeye is considered by many to be the most flavorful and tender steak.

What Primal Cut Does Prime Rib Come From?

Prime rib originates from the primal rib section of the cow. There are eight primal cuts of beef, and the rib is one of the most coveted.

The Beef Primal Rib Section

The primal rib section is located along the upper side of the cow’s torso, extending from the chuck section up to the loin. It sits beneath the backbone, spanning ribs 6 through 12.

This area contains numerous complex muscles, but the principal muscle is the longissimus dorsi, also referred to as the eye muscle. This ribbon-like muscle runs along the back of the primal rib section. It’s surrounded by fat and overlaid by the spinalis dorsi cap.

The spinalis dorsi cap is commonly called the ribeye cap. It’s the outer muscle that covers the longissimus dorsi. The ribeye cap is prized for its exceptional tenderness and beefy flavor.

Together, the longissimus dorsi eye muscle and the spinalis dorsi ribeye cap form the ribeye steak when the roast is sliced. They are central to the desirability of the prime rib.

Why is the Rib Primal So Special?

There are a few key reasons the rib primal produces uniquely tasty beef:

  • Marbling – The rib section contains substantial marbling, which bastes the meat during cooking and ensures tenderness.

  • Muscle use – The rib area doesn’t get as much exercise as chuck or round, so meat is more tender.

  • Fat content – Generous fat content throughout the rib region flavors and tenderizes the meat.

  • Bone – The ribs impart extra flavor during roasting.

Thanks to these attributes, rib cuts like prime rib and ribeye deliver the ultimate in rich, beefy flavor and a tender texture.

How is Prime Rib Prepared from the Rib Primal?

Master butchers carefully remove the entire prime rib section from the carcass in one piece. The ribs are left attached to the longissimus dorsi muscle.

To create a prime rib roast, the butcher will trim excess fat and remove the feather bones from the roast, while keeping ribs 6-12 intact. The ends may be tied to maintain an even shape.

The prime rib can then be seasoned and roasted whole before slicing. Carving between the ribs yields individual portions, typically called beef ribeye steaks when served as single portions.

The prime ribeye is also one of the few cuts that can be served with the bone still attached as a dramatic Tomahawk steak or Cowboy cut ribeye.

Prime Rib Roast vs Ribeye Steak

Understanding the difference between a prime rib roast and a ribeye steak is important:

  • A prime rib roast is the entire rib section with ribs 6-12 still attached. It’s roasted whole as one large piece of meat.

  • Ribeye steaks are individual steak portions cut from the roasted prime rib, boneless or bone-in.

While a prime rib roast yields ribeye steaks once sliced, preparing a whole roast versus a single steak requires different techniques.

Why is Prime Rib Roast Special?

Beyond originating from a prized section of beef, the prime rib roast itself has qualities that make it exceptional:

  • Stunning presentation – The standing roast is served whole for an impressive tableside carving.

  • Flavorful crust – Low-heat roasting develops a deeply browned, succulent crust.

  • Tender and juicy meat – The ribeye muscle stays moist thanks to the bone and fat.

  • Range of doneness – Slow roasting allows meat toward the ends to cook more for greater variety.

  • Convenience – One roast feeds a crowd rather than cooking individual steaks.

Because of these advantages, prime rib has become a cherished centerpiece holiday dish.

Is Prime Rib the Same as Prime Grade Beef?

Here’s a common point of confusion – the term “prime rib” does not automatically mean the roast is USDA Prime grade beef. The name refers to the primal cut, not the grade. Prime rib roasts can come from Prime, Choice, or Select grade cattle.

Always check the specific grade to ensure you’re getting USDA Prime. The highest quality prime rib comes from the top 2% of beef graded Prime.

Finding the Best Prime Rib Roast

For the ultimate prime rib experience, look for:

  • USDA Prime grade for peak tenderness, juiciness and flavor
  • Heavy marbling visible through the meat
  • Nice thick cap of flavorful fat on the outer eye muscle
  • Solid white fat throughout the roast
  • Deep red meat color with no gray spots

Buying the best quality roast you can find guarantees the finest final results.

With its beautiful presentation, singularly succulent and beefy flavor, and memorable holiday associations, prime rib occupies a special place in the pantheon of beef cuts. Understanding exactly where this regal roast originates only adds to its enduring appeal.

Know your Beef cuts: Prime Rib


What is a prime rib called at the grocery store?

When you’re shopping for prime rib, ask for a standing rib roast. That’s the name you’ll see at the butcher counter. The standing rib roast unsurprisingly comes from the rib section of the cow.

What cut of beef do you buy for prime rib?

Call it rib roast, standing rib roast, prime roast, or Grandma’s Easter specialty, the magnificent delicacy that is prime rib is delicious no matter what label you apply. This cut comes from the cow’s primal rib section. This primal is located behind the animal’s shoulder but in front of the lower back/butt region.

What is another name for prime rib?

At the store, “Prime Rib Roast” can go by different names including Rib Roast, or Standing Rib Roast (because it is positioned standing on the rib bones as it roasts). It can be found in the meat case with both boneless and bone-in options.

Is prime rib the most expensive cut of beef?

Prime rib can cost up to $17 per pound, making it one of the more expensive cuts of beef. T-bones usually cost around $11.99 to $16.99 per pound. Kobe beef typically costs about $300 per pound in Japan. Beef tenderloin is one of the expensive cuts costing around $25.99 per pound.

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