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Prime rib — also called a standing rib roast — is the pinnacle of beef roasting. Cut from ribs 6 through 12 of the steer (the most tender and richly marbled section), prime rib combines exceptional marbling with a distinctive beefy flavor that no other cut can match. When cooked correctly, it delivers a deeply caramelized exterior crust and a uniformly rosy, tender interior. The Prime Rib Calculator takes the classic time-per-pound method and applies it precisely based on your desired doneness level.
The classic prime rib cooking formula is elegantly simple: after an initial high-heat sear (450°F for 15–20 minutes), reduce oven temperature to 325°F and cook at the following rates: 15 minutes per pound for rare (120°F), 17 minutes per pound for medium-rare (130°F), 20 minutes per pound for medium (140°F), and 25 minutes per pound for well done (160°F). Medium-rare is the almost universally recommended doneness for prime rib — at this temperature, the extensive marbling has begun to render, basting the meat from within and producing unmatched juiciness.
Bone-in prime rib roasts cook slightly slower than boneless because the bone acts as an insulator along one side of the meat. However, many cooks prefer bone-in because the bone contributes to flavor during cooking. A standard bone-in prime rib has 2–3 bones per 4–6 lbs of meat; a full 7-bone prime rib weighs 14–18 lbs and feeds 12–16 people.
The most important rule: pull the roast from the oven when the internal temperature is 10°F below your target. Carryover cooking will raise the temperature by 8–12°F during the essential resting period. Tenting loosely with foil and resting for at least 20–30 minutes (longer for larger roasts) is non-negotiable — it allows the internal juices to redistribute throughout the entire roast rather than flowing out when carved.
Cook time = weight (lbs) × minutes per pound at 325°F (after 15-min 450°F sear). Minutes per pound: rare = 15, medium-rare = 17, medium = 20, well done = 25. Boneless roasts cook 2 min/lb faster due to lack of insulating bone. Pull temperature = target − 10°F for carryover. Rest time = max(20 min, weight × 3 min).
Medium-rare (130°F) is the gold standard for prime rib. At this temperature, fat has partially rendered, collagen has softened, and the meat is maximally juicy and tender. Cooking past 145°F significantly reduces juiciness. These times assume a room-temperature roast; if cooking from refrigerator, add 15–20% to cook time.
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7 lb bone-in prime rib. Pull at 120°F, rest 21 min. Final temperature: 130°F medium-rare. Serves 6–7.
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4 lb boneless roast cooks faster. Pull at 110°F, rest 20 min, reach 120°F rare. Serves 4–5.
Medium-rare (130°F) is overwhelmingly recommended by chefs and experts. At this temperature, the abundant fat marbling has begun to render, basting the meat internally, and the muscle fibers remain tender and juicy. Cooking beyond 145°F significantly reduces both juiciness and tenderness.
Prime rib is a large ribeye roast (2–7 bones) that is roasted whole, then sliced into individual portions. A ribeye steak is simply a prime rib portion sliced before cooking. Both come from the same section (ribs 6–12), but roasting the whole piece produces better moisture retention.
Uncovered for the entire cooking time to allow the exterior to brown and crust properly. The fat cap acts as a natural basting mechanism. Cover loosely with foil only during the resting period to retain heat without creating steam that softens the crust.
Season at least 1 hour before cooking for basic salt-and-pepper seasoning. For deeper flavor, dry-brine in the refrigerator uncovered for 24–72 hours with salt only (about 1 tsp per pound). The surface dries out and browns more beautifully, and salt penetrates deeper into the meat.
As a main course with sides: plan for 1 bone or 1 pound of bone-in roast per person (about 8 oz cooked meat after shrinkage). For boneless: 8–10 oz raw per person (6–7 oz cooked). For large appetites or few sides, increase to 1.25 lbs per person.
It is not recommended for prime rib — you lose the essential crust and browning that defines the dish. Prime rib is best roasted in the oven. If slow cooking is required, use a chuck roast instead, which has similar marbling and benefits from braising.
An alternative method: preheat oven to 500°F, cook at 500°F for exactly 5 min per pound, then turn off the oven (do not open the door!) and let the roast sit in the closed oven for 2 hours. Results in medium-rare throughout but requires exact timing and is not reliable for very large or small roasts.
Full-bodied red wines with enough tannin to cut through the rich fat: Cabernet Sauvignon, Bordeaux blends, or Malbec are classic pairings. Aged Burgundy (Pinot Noir) is a more delicate choice. Avoid light or sweet wines — the richness of prime rib overwhelms them.
Yorkshire pudding is a traditional English accompaniment to standing rib roast. Made from eggs, flour, and milk baked in hot beef drippings, it puffs dramatically into a hollow, custardy, crispy shell. It is the classic partner to prime rib in British and American tradition.
Place in a 250°F (120°C) oven in a covered dish with a splash of beef broth until the internal temperature reaches 130°F (about 20–25 min for 1-inch slices). Do not microwave — uneven heating ruins the texture. Alternatively, sear in a hot cast iron skillet 1–2 min per side for quick reheating.
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