Prime Rib Cooking Time: Exact Minutes Per Pound Guide

Prime rib requires 15-20 minutes per pound at 325°F to reach proper internal temperature. For medium-rare (recommended), cook until thermometer reads 130-135°F, then rest 20-30 minutes. A 7-pound roast typically needs 1 hour 45 minutes to 2 hours 20 minutes total cooking time.

Perfectly cooked prime rib separates holiday meals from ordinary dinners. Get the timing wrong, and you'll face dry, overcooked meat or unsafe undercooked beef. This guide delivers science-backed cooking times verified by professional chefs and food scientists—no guesswork needed. You'll learn exactly how long to cook prime rib for your specific roast size, oven temperature, and desired doneness level.

Understanding Prime Rib Cooking Fundamentals

Prime rib's rich marbling demands precise temperature control. Unlike leaner cuts, this roast continues cooking significantly during resting due to its dense muscle structure and fat content. The USDA Food Safety and Inspection Service confirms that carryover cooking raises internal temperature 5-10°F after removal from oven (source).

Professional chefs like those at the Culinary Institute of America emphasize that time alone doesn't determine doneness—internal temperature is the critical factor. A meat thermometer remains the single most important tool for perfect prime rib.

Prime Rib Temperature Guide: Science Over Guesswork

Forget unreliable time-per-pound calculations. The following chart shows actual cooking progression based on research from America's Test Kitchen and USDA data:

Starting Temp	325°F Oven (15 min/lb)	275°F Oven (20 min/lb)	Target Internal Temp
Room Temp (70°F)	120°F at 75% time	120°F at 85% time	Rare: 120-125°F
Room Temp (70°F)	130°F at 90% time	130°F at 95% time	Medium-rare: 130-135°F
Room Temp (70°F)	140°F at 100% time	140°F at 105% time	Medium: 140-145°F

Notice how lower oven temperatures extend cooking time but produce more even heat penetration. This explains why many chefs now recommend the reverse sear method for prime rib—starting low then finishing hot.

Step-by-Step Prime Rib Cooking Timeline

Follow this professional-tested sequence for foolproof results:

Preparation (1-24 hours before cooking)

• Remove packaging and pat dry with paper towels
• Season generously with salt (1 tsp per pound) and let air-dry uncovered in refrigerator
• Bring to room temperature 2-4 hours before cooking for even heat distribution

Cooking Phase (Active monitoring)

1. Preheat oven to 325°F (conventional) or 300°F (convection)
2. Insert probe thermometer into thickest part, avoiding bone
3. Roast until thermometer reaches 115-120°F for medium-rare (about 15-20 min/lb)
4. Remove when 5-10°F below target temperature (carryover cooking will finish the job)

Resting and Finishing (Critical step!)

Cover loosely with foil and rest 20-30 minutes. This allows juices to redistribute while temperature rises to perfect doneness. For extra crust, broil 3-5 minutes after resting.

Adjusting Cooking Time for Your Specific Roast

Several factors change how long you cook prime rib. Consider these variables:

Bone-In vs. Boneless Prime Rib

Bone-in roasts cook slightly faster (about 10-15% less time) because bones conduct heat. When calculating cooking time for bone-in prime rib, subtract the bone weight from total weight.

Oven Temperature Variations

Lower temperatures (250-275°F) require longer cooking but produce more even results. Use this adjustment formula:

Adjusted Time = (Standard Time) × (325 ÷ Your Oven Temp)

Example: For a 7-lb roast at 275°F: (110 min) × (325 ÷ 275) = 129 minutes

Troubleshooting Common Prime Rib Problems

Cooking too slow? Check oven calibration with independent thermometer. Most home ovens run 25°F cooler than displayed.

Uneven cooking? Rotate roast 180 degrees halfway through cooking. Position fat cap up for self-basting.

Overcooked? Slice thinner and serve with flavorful jus. Next time remove 5°F earlier and rest longer.

Undercooked? Return to 350°F oven until 5°F below target, then rest. Never slice undercooked prime rib immediately.

Professional Tips for Prime Rib Success

Top chefs recommend these often-overlooked techniques:

• Use a leave-in probe thermometer for real-time monitoring
• Place roast on V-rack to promote air circulation
• Season with coarse salt 24 hours ahead for deeper flavor penetration
• Cook standing rib roast fat-side up for natural basting
• Rest on wooden cutting board (not metal) to prevent moisture loss

Serving and Storage Guidelines

Carve against the grain into 1/2-inch slices using a sharp carving knife. Serve immediately after resting for best texture. Leftovers keep refrigerated 3-4 days per USDA guidelines. Reheat gently in 275°F oven until internal temperature reaches 130°F.

How long to cook prime rib per pound at 350 degrees?

At 350°F, cook prime rib for 12-15 minutes per pound. A 6-pound roast needs approximately 1 hour 15 minutes to reach 130°F for medium-rare. Always verify with a meat thermometer rather than relying solely on time.

Should I cook prime rib covered or uncovered?

Cook prime rib uncovered throughout the entire process. Covering traps steam which prevents proper browning and crust formation. Foil should only be used during the resting period after cooking is complete.

What temperature is medium-rare prime rib?

Medium-rare prime rib registers 130-135°F on a meat thermometer. Remove from oven at 120-125°F to account for 5-10°F temperature rise during resting. This yields perfectly pink, juicy meat with optimal texture.

How long should prime rib rest before carving?

Prime rib needs 20-30 minutes resting time before carving. This allows juices to redistribute throughout the meat. Resting too briefly causes juices to escape when sliced, resulting in dry meat.