When it comes to serving a show-stopping meal, prime rib is the king of the dinner table. Whether you’re preparing a holiday feast or a celebratory Sunday dinner, knowing how long to cook prime rib per pound is key to achieving tender, juicy, and perfectly cooked meat.
This guide will walk you through everything you need to know—cooking times, temperatures, preparation tips, and more—so you can serve the perfect prime rib every single time.
What Is Prime Rib?
Prime rib, also known as standing rib roast, is a cut of beef taken from the primal rib section. It’s richly marbled, incredibly flavorful, and best served medium rare to medium to retain its tenderness. The term “prime” refers to the USDA grading system, but not all “prime rib” roasts are USDA Prime—some are Choice grade, which is also excellent for roasting.
How Long To Cook Prime Rib Per Pound?
The cooking time for prime rib depends largely on two factors:
- Your preferred level of doneness
- The oven temperature you choose
Here’s a quick cheat sheet:
| Doneness | Oven Temp | Time Per Pound |
|---|---|---|
| Rare (120°F) | 325°F | 15-17 minutes |
| Medium Rare (130°F) | 325°F | 18-20 minutes |
| Medium (140°F) | 325°F | 20-22 minutes |
| Well Done (160°F) | 325°F | 24-26 minutes |
So, for example, a 6-pound prime rib cooked at 325°F for medium-rare should take about 108 to 120 minutes, or 1 hour 48 minutes to 2 hours. Always use a meat thermometer for accuracy!
The “Low and Slow” Method
Another popular technique is the low-temperature roasting method, which uses a 200°F oven. This takes longer—about 30 to 35 minutes per pound—but it ensures an even cook throughout the roast.
Example:
- A 5-pound roast at 200°F would take approximately 2.5 to 3 hours.
- Always finish with a high-heat sear (500°F for 5–10 minutes) to create a flavorful crust.
How To Tell When Prime Rib Is Done
The best way to ensure perfect results is to use a meat thermometer. Here are the internal temperatures to look for:
- Rare: 120°F (remove at 115°F; rest to 120°F)
- Medium Rare: 130°F (remove at 125°F; rest to 130°F)
- Medium: 140°F (remove at 135°F; rest to 140°F)
- Well Done: 160°F (not recommended for prime rib!)
Remember: Prime rib continues to cook while resting, so pull it out 5°F early.
Step-By-Step Prime Rib Recipe
Let’s walk through a full recipe for a 6-pound prime rib roast, aiming for medium rare.
Ingredients:
- 6-lb bone-in prime rib
- 2 tbsp kosher salt
- 2 tbsp freshly ground black pepper
- 1 tbsp garlic powder
- 1 tbsp onion powder
- 2 tbsp fresh rosemary (optional)
- 2 tbsp olive oil
Instructions:
1. Bring to Room Temperature
Let the prime rib sit out for 2 hours before cooking to ensure even roasting.
2. Season Generously
Mix salt, pepper, garlic powder, onion powder, and rosemary. Rub the roast all over with olive oil and then coat with the seasoning mixture.
3. Preheat the Oven
Set your oven to 325°F for standard roasting or 200°F for slow roasting.
4. Roast
Place the rib roast in a roasting pan, bone side down or on a rack. Insert your meat thermometer into the thickest part of the roast.
- At 325°F, cook for 18-20 minutes per pound for medium rare.
- For a 6-lb roast: cook for 108 to 120 minutes (1 hour 48 mins to 2 hours).
5. Rest the Roast
Remove the roast when the thermometer reads 125°F for medium rare. Tent with foil and let it rest for 20 to 30 minutes before slicing.
6. Slice and Serve
Carve against the grain and serve with your favorite sides like mashed potatoes, creamed spinach, or horseradish sauce.
Tips for the Best Prime Rib
- Use a Thermometer: A digital meat thermometer is your best friend.
- Let It Rest: This redistributes juices and improves flavor.
- Don’t Skip the Crust: High heat at the beginning or end helps develop a savory crust.
- Dry Age at Home (optional): Letting your roast sit uncovered in the fridge for a few days can intensify the flavor.
Bone-In vs. Boneless Prime Rib
Both are delicious, but they cook a little differently:
- Bone-In: More flavorful, but takes slightly longer to cook.
- Boneless: Easier to carve and cooks more evenly.
If using a boneless roast, reduce cooking time by about 2-3 minutes per pound.
Reverse Sear Method
This modern method starts low and finishes high:
- Roast at 200°F until 10°F below your desired doneness.
- Let rest.
- Sear at 500°F for 5-10 minutes before slicing.
This gives you more consistent doneness from edge to center.
How Much Prime Rib Per Person?
Plan for:
- 1 pound per person (bone-in)
- 3/4 pound per person (boneless)
If you want leftovers (and who doesn’t?), add a little extra.
Frequently Asked Questions
How long to cook a 5-pound prime rib?
- At 325°F for medium rare: 90 to 100 minutes.
- At 200°F (slow roast): 150 to 175 minutes, then sear.
Can I cook prime rib at 350°F?
Yes, but it may cook faster and have less even doneness. Stick to 325°F or lower for the best results.
What’s the best temperature for cooking prime rib?
325°F for traditional roasting, or 200°F for the low and slow method.
Final Thoughts
Cooking the perfect prime rib isn’t complicated—it’s all about knowing how long to cook prime rib per pound and using a meat thermometer for accuracy. With these techniques, you’ll be serving up a juicy, tender roast that’ll have your guests raving.
So whether it’s Christmas dinner, a birthday feast, or just a cozy winter weekend, prime rib can be your signature dish. Just follow this guide, and you’ll be carving like a pro in no time.