The Ultimate Guide to Prime Rib

There is nothing more impressive than a slow roasted, deeply crusted, perfectly cooked prime rib landing squarely in the center of a full dinner table.

Prime rib might be the perfect cut of beef. It’s got a little something for everyone. Intense well-marbled fat forward hits for the fat-is-flavor stans (that’s me). Supple, rosy tender parts for the filet/tenderloin fans. Savory beefiness in bulk for the ribeye-is-king crowd. And, last but not least, a deep dark crust for those guys who need to insert Maillard reaction into any conversation involving beef.

What is prime rib

Prime rib is one of the largest cuts of beef you can buy as a normal home cook. You buy it as a roast made of a full rack of 7 ribs. These ribs are commonly spoken of as being from ribs #6-#12. The best way to think of a prime rib is a super high quality tomahawk or bone-in ribeye, stretched out to a foot thick. It’s true: the meat that comes in a prime rib roast is the same stuff you make ribeyes and tomahawks from.

How to make the best prime rib

Before we talk about anything else: to make the best prime rib you can make, use a meat thermometer. Below are some good formulas and ballpark techniques, but if you’re cooking a $100+ piece of meat, you should consider investing in a good meat thermometer. Every oven is different and every roast goes in the oven at a different temp, so a meat thermometer is essential.

The best kind for this sort of thing is a leave in meat probe that beeps you when the target temp is heat. The probe your oven probably comes with is a great option too. But even if all you have is an instant read thermapen, it’s better than nothing.

Parts of a prime rib

Prime rib looks like just one big homogenous hunk of meat, but it’s three delicious parts with their own taste and tenderness:

1. Spinalis dorsi aka rib cap: This is considered a well kept chef’s secret: the greatest cut of steak, bar none. All the complexity of a flank steak, the fatty marbling of a ribeye, and the tenderness of a filet, in one steak. This cut is separated from the main body of the prime rib by a large layer of fat. Back when people vilified fat, spinalis dorsi used to be cut off and saved for the butcher or kitchen so that the ribeye steak could be presented “cleaner”. These days, especially if you order a bone-in ribeye, they just leave it on. It really is the best part.
2. Ribeye: This is the main body of a slice of prime rib. It’s literally the same as a ribeye steak. It will be well marbled, tender, and complex tasting.
3. Iliocostalis: Some people liken this to a long thin tenderloin. It’s also called the lip or nose of a prime rib. It doesn’t have a good reputation because it’s often smaller, fattier, and not very toothsome, but I think it’s an intensely beefy and tender cut because it sits right next to the bone. Iliocostalis used to be cut off and not served with the prime rib, as it wasn’t considered ‘prime’ enough, but these days, most butchers will leave it on for you to decide on.

Why make prime rib?

But why go to all this trouble instead of just getting seven steaks? Because, prime rib is insanely delicious. It’s basically the cheapest bone-in ribeye you can get at an extremely high quality for price ratio. Done right, it’s easy, forgiving, impressive, and satisfying. The best part is the leftovers can be reheated as some of the best steaks you’ll ever have.

Prime rib cooking time

If you are cooking for a hungry house and want to know how to plan on timing such a large roast to be just ready for dinner, there’s a super easy formula based on the doneless you prefer. This isn’t one of those pro-chef-speed formulas that no one can realistically achieve, it’s pretty loose with the times so you can depend on it, even if you are relaxing, drinking wine, and consulting your phone every so often for the next step of the recipe. That said, using a meat thermometer is vitally important. And, so is planning on serving appetizers and drinks before the main course for anyone who is extra hungry.

The formula is simple – assume:

• 2 hours for temper
• 30 mins for searing
• 15-30 minutes per pound (in 5 minute increments – medium rare is 20 minutes/pound)
• 30 minute rest

The prime rib that we made here was about 6 lbs, which means it was a 2 hour cook time plus 3 hours for everything else. It squarely hit the 5 hour mark from taking it out of the fridge to the first bite.

Prime rib vs steaks

Why should you make prime rib instead of steak or some other cut? Because, it’s cheaper than steak by two- to three- times, it’s easier to make, and there’s nothing more impressive than a giant roast of beef landing squarely center on the dinner table.

The advantage of steak is that you can cater to different doneness preferences, but there are so many disadvantages, such as steaks being more expensive, needing more pans (aka more dishwashing), and being so much messier, smokier, and splatterier.

Besides, you can cut down a prime rib into steaks before or after cooking. You can’t glue steaks together into a prime rib roast. Overall, if you can justify the initial outlay, prime rib beats steak every time.

A smaller prime rib

In fact, prime rib is such a good competitor to steak that I think it’s worth it to consider a smaller prime rib, even if its just for two of you, or even if you live alone. Ask your butcher to cut you 2-3 ribs worth. Where we live, it’s half the cost vs bone in ribeye, and my butcher sells even two ribs, which is just two bone in ribeyes stuck to each other.

If you are buying by the rib at a really nice butcher shop, you may get choice of which rib bones you want. The “front” is rib number 12, which is very tender with a large ribeye steak, and the “back” is rib number 6, which is more marbled and complex.

Prime rib roast

A prime rib can actually be closer to 24 inches thick, although you don’t have to opt for the full rack. Any good butcher will cut you whatever thickness you need.

If you can, you should go for broke and get the full rack because it’s way cheaper than individual steaks of the same quality. A prime rib roast can be split into steaks if you’re so inclined. Even if you are only cooking for 2 people, you can buy a whole rack for cheap and split it up into seven 2” thick steaks for much less than you’d pay if you’d just bought steaks.

But, the whole point of a prime rib is to roast it to perfection, with a deep dark crust and tender, rosy pink insides, so I recommend you grab a 2-4 rib segment (or more if you want) and go to roasting town. Roasting is way easier than cooking 7 steaks and so much more impressive too. Even better, with the right tools, it’s easy to do it perfectly, every time.

Bone in or boneless or tied back

When you ask for prime rib, you might be presented with one of three options: bone-in, boneless, or the bones cut off, but tied back on. Each has its pros and cons:

• Bone in: The most flavor, but also the hardest to handle. Besides the weight, you can only cut slices between the bones. If you don’t intend to use the bones, these will also be more expensive, because while they cost less per pound, you still pay for the bones. They have the most flavor by far.
• Boneless: The easiest to handle, the easiest to cook, but a little less impressive. Boneless is great if you’re a crust fan (who isn’t?) because you get maximum crust without any pesky bones getting in the way. You’re also able to slice it to any thickness you like. To me though, this option doesn’t really feel like prime rib, just fancy roast beef.
• Bones cut off and tied back on: This might actually be the version you’re most likely to run into depending on where you live. This one seems to sells the best, and some internet sources say it’s great for seasoning the meat because you can get under the bone.

Where to buy prime rib

Because it’s not a super popular cut and because of how expensive it is, outside of Christmas and Thanksgiving, and maybe Easter, you may have a hard time finding prime rib. The best place to get a prime rib, by far, is your local butcher. Not only will they often have it because they have the whole cow in stock, they’ll be more willing to cut you exactly as much as you need.

Your other option is a special order from a grocery store’s meat department. I checked with whole foods and they said they were able to get a prime rib the next day. I went with the local butcher, but whole foods was actually cheaper.

You can also get some awesome (and awesomely expensive) prime ribs from online meat purveyors like snake river farms or costco. If you’re lucky, you might find some prime rib locally at costco in its appropriately named prime beef department – just ask.

How to choose the best prime rib

Believe it or not, prime rib was named before the USDA settled on its grades. Depending on who you believe, prime rib is either called prime because it’s the best cut of beef, or because its a primal cut. Either way, prime rib is not always USDA prime.

The difference between a USDA prime and a USDA choice (the second best) prime rib is between 25%-50% more money. Beyond that, if you go to a good butcher, you also have options for organic, dry aged, grass fed, wagyu, and more.

So how do you choose a good prime rib? Decent marbling is usually a sign of a happy animal, and that means a good tasting cut of meat. Grass vs corn fed is a matter of opinion, and many people don’t like the extra floral and complex taste of grass fed beef, but I don’t think there’s anyone who doesn’t like tender, well marbled beef.

How to cook prime rib

Here’s how to cook a perfect prime rib, every time:

1. Preheat your oven to 450ºF.
2. Brown the two sides in a cast iron pan: optional, but highly recommended, especially when you have a smaller roast that’s easier to handle. The smoke detector may possibly go off.
3. Brush with butter or oil, then sear in the oven at 450ºF for 15 minutes.
4. Set the oven to 200ºF and open the oven door for about 15 minutes, or until the oven temp drops to 200ºF if you have an oven thermometer. The smoke detector may possibly go off, again.
5. Cook for 20 mins per pound for medium rare, or until your meat thermometer goes off. Temperatures are below.
6. Rest for 30 mins, then slice and enjoy!

Trimming

How much fat you need to trim away depends on how much you love fat. If you trim all the fat away from the edges, you’ll get a much better sear, but that fat is super flavorful and tender – nothing like the tough chewy fat you might encounter from lesser cuts. My butcher left the fat cap on the spinalis, so I removed and froze that, but left the fat on the iliocostalis for extra flavor.

Do you really need to temper the meat?

Unfortunately, yes, you do really need to temper the meat. Tempering the meat – which is really just a fancy way of saying “leave it out on the counter to come to room temp” – equalizes the temperature of the meat so it cooks evenly, plus it lowers cooking times. You can also use this time to briefly dry-brine the meat (below). For a smaller 2-3 bone roast, you can get away with 2 hours of tempering. For a full rack, you’ll want to temper at least 4 hours.

Dry brining

Dry brining is just liberally seasoning the meat and leaving it in the fridge for 12hrs to 4 days to let the salt penetrate the meat. This process is supposed to pull out the excess moisture from the beef for a more tender and tasty piece of meat. I’m not sure I personally agree with this. Salt never penetrates that much in a dry brine. But if you have a day or two before you want to cook the beef, it doesn’t hurt. Just lightly sprinkle some salt all around the roast, then place on something to catch the juices. Loosely cover and refrigerate until you are ready to use.

Prime rib temperatures

Prime rib, like all roasts, continues cooking after it leaves the oven while the thermal energy redistributes. For us, this seems to be a 6 degree rise, but your results may vary based on how warm your house is. Basically, 6 degrees is a pretty good estimate, however, so you want to take your roast out 6 degrees before your target temperature. For a quick reference, my target temps are below.

• Rare: 125ºF – remove at 119ºF
  
• Medium-rare: 130ºF – remove at 124ºF
  
• Medium: 135ºF – remove at 129ºF
  
• Medium-well: 140ºF – remove at 134ºF
  
• Well done: ?‍♂️

The importance of a meat thermometer

A meat thermometer is essential. That old adage about the feel of your ear or touching your thumbs to fingers? Not for important cuts of meat, in my opinion. I recommend an oven probe; one that beeps when the target temp is hit. They can be really cheap, extremely expensive wireless app driven, or something in between. If you have an instant read or thermocouple style, be sure to check often that the roast doesn’t get overcooked.

Sauces

I don’t do a sauce or a rub with my prime rib. Because it’s such a large piece of meat, most likely you will not get a lot of extra flavor into the inside – just its core beefiness. For some people that’s more than fine. The big savory beefy taste is more than enough, especially when paired with some nice flaky sea salt. For others, steak sauces are always welcome. If you’re in that crowd, you should check out our steak sauce roundup.

How to reheat prime rib

You’ll probably likely have some leftover prime rib. You’ll also most likely hear that you should reheat the leftovers in a low oven. I disagree: by far the best way to reheat prime rib leftovers is to cut the remaining pieces into 2” thick steaks (if you can). Liberally season any cut sides, then sear 2 minutes per side in a cast iron pan. It makes for amazing steaks.

Smoke alarms

Depending on many factors – if your smoke alarm is close to your kitchen, if your oven is less clean, or if your hood fan is a little weaker – you should be prepared for your smoke detector to go off during the browning stages. Be sure to check if your smoke detector has a hush button. Or, have a helpful assistant standing by with a large towel ready to fan when you first drop the roast into the cast iron pan to brown and again when you open the 500ºF oven door.

And that’s it, perfect prime rib, every time. I hope you enjoyed this guide and you’re inspired to make a giant, super satisfying chunk of meaty goodness soon!

-Mike