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How Long To Cook Prime Rib Per Pound: Optimal Cooking Times

Chefs, cooks, and barbecuers have discussed this for ages, and it seems there is not a clear consensus yet. Knowing how long to cook prime rib per pound is essential if you’re just starting. You must have a blueprint for how you’re going to cook it, and that begins with consistent temperature.

How Long To Cook Prime Rib Per Pound?

Cooking prime rib to your liking is based on how heavy your prime rib weighs and to what doneness you prefer your prime rib. For those that like it rare, you should cook your prime rib for 11-12 mins/lb. If you want Medium, cook your prime rib at 12-14 mins/lb. For well-done prime rib, cook it for 15-16 mins/lb.

Why Does Prime Rib Take So Long?

Prime rib can be an intimidating cut of meat to roast because of its size and cost. You want to ensure you get the correct technique even on the first try because ruining a delicious piece of meat is simply too expensive just to throw away. 

Prime rib takes a while to cook because of multiple factors;

Size of Cut

This is classified as a roast, and therefore the middle temperature must reach the minimum amount recommended by the FDA for safe consumption. The only way to do this is to slowly and evenly raise the temperature of your prime rib

The bigger the roast, the more difficult it is to get an even cook. This is why so many chefs will tie their roast with butcher twine. The twine keeps a symmetrical shape, so there are no gaps where air and heat can get in and cook areas faster than others. 

More Fat And Intramuscular Tissue

So much flavor is derived from the marbling that prime rib possesses. This flavor is only accessible if appropriately cooked and the fat is slowly rendered down. This can only happen at a low temperature. 

If fat is cooked at higher temperatures, it can seize up and create a very firm and chewy texture. Not only is this unenjoyable to eat, but it also robs the roast of any fat drippings that could be absorbed by the leaner parts of the cut. 

We take our time with prime rib to ensure all these muscles and fat have a chance to break down so we can chew them easily and enjoy the flavor they bring to the table. 

The Bones Need Time

Cooking with the bone on is the easiest way to impart natural flavor to your prime rib or any kind of meat, for that matter. Bones contain marrow which turns into a gelatinous texture if cooked correctly. Extracting this flavor is the sign of a professional prime rib chef. 

Even after you’re done with your meal and you’re ready to throw out the bones, DON’T. Those bones can be used to make beef stock which will enhance the flavor of many more dishes. You can use it to make beef barley soup or any kind of fried rice dish. 

You can also use the bones as compost for your garden. They possess high-grade natural nutrients that your crops will use to grow big and strong.  

Cooking Prime Rib on A Grill

While this may sound like a good idea because you want to impart some natural smoking flavor that only a fire can create, we strongly advise against it. Grills are designed to cook hot and fast; a prime rib requires low and slow. 

Your grill will not be able to maintain a steady temperature over the course of a few hours to properly render the fat. This will leave your prime rib overcooked and dry. 

You can use your grill at the end of the cook to get a good crust or bark on the outside. Once your prime rib is just about done, finish it on a searing hot grill. This will add some crunch and make it easier for the juices to get locked in while resting. 

If you really want a smoky flavor and a solid bark, try smoking your next prime rib. If you have a dedicated smoker, use all the same instructions that you would follow to cook it in the oven. Using a smoker means you may not have to sear in order to get a good bark, as this will happen naturally in the smoker.  

Cooking Time Table

@325°per pound4-6 lbs.7-9 lbs.10-12 lbs.13-15 lbs.16+ lbs.
Rare11 mins/lb.11 mins/lb.12 mins/lb.12 mins/lb.12 mins/lb.
Medium-Rare11 mins/lb.12 mins/lb.12 mins/lb.13 mins/lb.13 mins/lb.
Medium12 mins/lb.12 mins/lb.13 mins/lb.13 mins/lb.14 mins/lb.
Medium-Well14 mins/lb.14 mins/lb.14 mins/lb.14 mins/lb.15 mins/lb.
Well14 mins/lb.14 mins/lb.15 mins/lb.15 mins/lb.16 mins/lb.

How To Prepare Your Prime Rib For Cooking

Now that you know how long to cook prime rib per pound, you can begin the cooking process;

  1. Remove the prime rib from the fridge and leave it on the counter until it reaches room temperature. This will help the roast cook evenly throughout and avoid any areas that may be under or overcooked. 
  1. Sit your prime rib on a roasting rack in a roasting tray with the bone side down. This will help you get a good bark all around the outside while still allowing the juices to drip down. Use the juices to create an au jus to be served alongside your finished and sliced prime rib
  1. Before roasting, and no matter how many pounds your prime rib is, always season it. There are many ways to do this, but I recommend making a flavorful butter and then spreading that on all sides. This will help leach flavor and moisture deep within your roast over the long cook time. 
  1. Some home cooks like to sear at the start of the cook for convenience. Preheat your oven to 500° and put your prepared prime rib in for 15 mins. This intense heat will scorch the outside of the roast and give you a head start on creating bark without having to use another cooking technique later. 

The Most Optimal Temperature For Any Weight

There is some debate about what is the best temperature to cook prime rib. We always recommend going for 325° because it’s the hottest you can get without cooking the prime rib too fast. 

Knowing how long to cook prime rib per pound is a great start and definitely knowledge you want to have. But to ensure the best cook every time, finding the right temperature for the size of prime rib and knowing how accurate your oven is are both more important.

You can cook prime rib anywhere from 250° – 375° and be able to find expert articles instructing you how to do so. While these will make an edible prime rib, they won’t be the best. If you think 325° is too high, then feel free to go lower. 

I’ve found that lower temperatures make it easy to monitor your internal temperature but just take too long. At 325°, you can render all the fat and break down all the connective tissue and still not have to wait as long as you would when cooking at temps under 300°.  

Reheating Prime Rib

Reheating prime rib out of the fridge is done the same way as when you cook it because it all depends on how many leftovers you have. If you still have a sizable chunk of prime rib, then you want to wrap it in tin foil and bake it in the oven. This should be done at 275° and will take an hour or so if you’re still left with more than a couple of pounds. 

If you just have a few slices left, then the microwave will do just fine, and hopefully, you have some spare au jus to accompany it. Be careful with the microwave, though, because it has a tendency to dry out the meat. You can avoid this by putting your prime rib slices in a sealable microwave-safe container. Just be sure to leave a crack for the steam to escape. 

How Long To Cook Prime Rib Per Pound When Frozen

We strongly urge you never to do this. The amount of water in a frozen prime rib will evaporate and cause your meat to steam rather than cook. This removes all the flavor and causes a chewy texture. 

Always defrost your prime rib before cooking it. This may require more planning on your part, but the cost of prime rib is so high that you don’t want to take any chances. Plan your cook from 48 hours ahead of when you want to serve, maybe even more if you have a large prime rib and want to smoke it low and slow. 

FAQs

What Is The Most Optimal Cooking Temperature For A 3-Bone Prime Rib?

The most optimal cooking temperature for a 3-bone prime rib is 325°. At this temperature, you can create a nice bark on the outside while still slowly rendering the fat and breaking down the intramuscular tissue for a tender and juicy result. You can use a lower temperature, but it will take longer, and the results won’t be much different.  

What Is The Optimal Cooking Temperature For A 6-Bone Prime Rib?

The optimal cooking temperature for a 6-bone prime rib is still 325°. However, this size prime rib will take a much longer time to cook. You don’t want to increase the temperature simply because there is more meat, which will cause the fat to seize up and become tough, chewy, and hard to slice. Patience is the key when cooking a prime rib of this size, but trust in the cooking temperature of 325°.

Are Convection Ovens Better For Cooking Prime Rib?

Yes, convection ovens are better for cooking prime rib because they force the heated air around all sides of your roast. Convection means there is a steady stream of air movement within your oven’s cooking chamber. Since we are propping the prime rib on its bones, we want evenly heated air to surround the meat so that one side doesn’t cook faster than the other. Many ovens have this feature now, but if yours doesn’t, just allow your oven to preheat a bit longer and be sure to only open the oven door when absolutely necessary. 

How Do You Calculate Cooking Time For Prime Rib?

You can calculate the cooking time for prime rib by using this formula; actual weight x 12 mins per pound = X minutes total. You can then divide that by 60 to find out how many hours. For example, A 9 lb. roast x 12 mins per pound = 108 minutes total or (108÷60) 1.8 hours for a medium-rare to medium cook. 

Conclusion

Knowing how long to cook prime rib per pound is important information to start with, but it’s not the only info you need to produce mouth-watering beef. You must use this info and apply it to your specific cut and your specific method of heat. 

A smoker acts differently than an oven which acts differently than a convection oven. No matter how you run the numbers, you should always be monitoring the internal temperature of your prime rib via a remote thermometer. This is the closest you can get to guaranteed perfectly cooked prime rib every time.