Beef

How to Cook A Perfect Prime Rib Roast

Prep Time 2 hrs · Cook Time 5 hrs · Recipe by Martin Earl

Get spectacular, rich, savory crust with edge-to-edge pink internal doneness.

If you're looking for that spectacular, rich, savory crust outside, combined with edge-to-edge pink doneness on the inside with no unsightly gray band, look no further. You won't find better advice on the internet. That's because the secret of a perfectly done Prime Rib that your friends and family will be talking about for years to come is all about temperatures—before, during, and even after you cook. If you get the temperatures right, your Prime Rib will be perfect. If you don’t get the temperatures right, it won’t. And who knows more about temperature than ThermoWorks? No one, that’s who.

Prime Rib Temp for Perfect Doneness: 125°F (52°C)

An internal temperature of 125ºF (52ºC) should be the lowest temperature you see in the roast before pulling from the heat. There will be carryover cooking that will gently carry your rib right up to medium rare without going over. If you prefer Medium doneness, pull the meat at 130°F (54°C).

How To Cook Prime Rib: A Quick Overview

This topic is worth a deep dive, but we've pulled together a quick summary of the important information right here at the top for easy reference. We'll get into each piece in depth, but if you're in a hurry for the goods, here's the tl;dr.

(Time: 3-5 hours)

Selection: Buy the highest grade meat you can afford. Prime grade is best, but Choice grade works great. Plan on half a pound per guest.
Trim it: Trim any excess gristle or fat. Shoot for no more than 1/4"" fatcap.
Tie it: An even roast cooks better.
Season it: Generously apply kosher salt and fresh-ground black pepper to all sides. (Or use your favorite seasoning.)
Chill your rib: Put your tied prime rib into the freezer until it measures 30°F (-1°C) just below the surface. (More on this below.)
Sear it: Sear your prime rib in a piping hot skillet (cast iron if you’ve got one) with a surface temp of 400°F (204°C) or more until a dark brown crust forms all around. Don't neglect the ends!
Roast it (or smoke it): Place your seared prime rib on a rack on a shallow baking sheet in an oven preheated to 225°F (107°C).
Verify Doneness: Cook your Prime Rib Roast until the lowest internal temperature you can find with an instant-read thermometer is 125°F (52°C) for Medium Rare or 130°F (54°C) for Medium doneness.
Rest it: Remove the roast from the oven. Loosely tent with foil and let it rest on the counter for 30 minutes to allow for carryover cooking. It should get to between 130 and 134°F (55-57°C) for Medium Rare or to between 135 and 140°F (58-60°C) for Medium.
Carve it: Carve to your desired thickness.
Bask in the praise from your friends and family. If you carefully follow this method, you should have a deep brown, rich, savory crust outside, with perfect, edge-to-edge pinkness inside.

How to Cook Prime Rib: An in-depth look at everything you need to know

How you prepare and cook the meat itself is where all the glory is to be found. It makes no difference whether you like your Prime Rib bone-in, boneless, or with the bone cut off and tied back on. The preparation and attention to temperature are what really matter. So, here’s how to do it.

First, What Even Is Prime Rib?

A prime rib can go by other names—beef rib roast, ribeye roast, or standing rib roast (so called when it is bone-in and can be roasted without the meat touching the pan)—but regardless of what it is called, it comes from the 6th through 12th ribs of a steer, sandwiched between the chuck and the short loin.

It is primarily composed of the longissimus dorsi muscle that runs next to the spine. Because of its location high up on the back of the steer, this muscle is not well used. This lack of use means that this muscle develops to be much more tender than, say, the rear-leg muscles (the Round of beef): it is anatomically predisposed to tenderness.

Tenderness is, of course, only one of the attractive characteristics of this cut of meat. Perhaps the most notable feature of this cut is the deep, rich fat marbling. The “eye” of the rib is encircled by a ring of fat and connective tissue, outside of which lies the “lip” of the roast. Much of the whole roast is covered by a fat cap of varying thickness. It is those seams of fat that deliver rich flavor and a velvety texture, as well as keep the meat from drying out easily.

How to Select the Best Prime Rib Roast

Picking out a rib roast at the store is a big deal. You want the best roast you can get in your price range, but you don’t want to come up short at dinner. So what should you buy and how much of it should you get? Let’s look first at grading and quality.

The USDA's method of grading beef is solely based on fat marbling. It has nothing to do with how the beef is raised or its flavor. The more thoroughly marbled the beef, the higher the grade. Higher-grade beef will tend to be juicier, more tender, and more flavorful, but it will also cost significantly more. Which is why you want to buy the highest grade you can afford.

You may have heard that Prime Rib refers to a prime-grade rib roast. This is not true—at least, not necessarily. The term “prime rib” predates the USDA meat grading system and is a reference only to the fact that it is the best part of the rib section. In fact, in the USDA Food Standards and Labeling Policy Book, (pg 146), the USDA clearly states that, “PRIME RIB OF BEEF OR STANDING BEEF RIB ROAST FOR PRIME RIB: These products do not have to be derived from USDA prime grade beef” (emphasis in original).

Prime rib can be graded USDA Prime (it will cost you!), but it can also be USDA Choice or USDA Select. Choice is a nice intersection of quality and price, usually.So how much of this delicious, pricey beef do you need? That really depends on you and your guests, but as a general rule, figure about 1/2 pound of pre-cook weight per person on a boneless roast, or one bone per two people on a bone-in roast.

Bone-In or Boneless?

Which one should you buy? The debate has gone on for years, with the pro-bones arguing that the bones contribute more flavor, and, if pressed, insisting that the marrow was seeping in from the bones to the meat. This has been shown by J. Kenji López-Alt , a team at Texas A&M’s Meat Science Department, and Meathead Goldwyn to be untrue. The marrow in the ribs is the wrong kind for “seeping” and the bones themselves are pretty impenetrable—even to the gooey, tasty kind of marrow.

But there is one way in which leaving the bone in can actually have an effect: as a heat buffer. Having a shield of bone and connective tissue on your meat can help to prevent overcooking. But if you like your roast rare to medium-rare, it can actually lead to chewy, undercooked meat right near the bone.

In the end, you’ll have to decide based on your preference. A standing rib roast (which can be as small as two bones or as long as the full seven) is beautiful to behold, but more difficult to carve—you will probably just cut the bones off to serve it anyway. Yes, a bone-in roast will usually be cheaper per pound, but you will be paying for bone weight, which is not directly useful to you.*

On the other hand, boneless prime rib roasts are easy to cook, easy to carve, but cost more per pound. The choice is yours, but in the ThermoWorks kitchen, we most often cook boneless roasts.

Preparing Your Prime Rib Roast

Whether you have a boneless or bone-in roast, you should spend a moment examining your roast with a knife in hand before roasting. Giving it a proper trim will improve the flavor and accelerate the cooking.

How to Trim Your Prime Rib Roast:

Trim off any gristle and silver skin on the surface. (There is also often silver skin deeper in the fat, but leave that alone.)
Trim excess fat. A nice fat cap can enhance the mouthfeel of the Prime Rib but you don’t want more than ¼ inch of thickness.
Whether boneless or not, you have the option to trim off the flat part that extends away from the main muscle, called the ""tail."" We always do. This evens out the shape of the roast, which will help it cook more evenly.

* If you choose to get a bone-in roast, we recommend having your butcher prepare it “cut and tied,” with the bones cut off and tied back onto the muscle. This creates an easy carving situation while maintaining presentation and heat-buffering advantages. The bones are fun and tasty to gnaw on after dinner, or you can use them to make a tremendous beef stock.

How to Tie Your Prime Rib Roast

Prepare your trimmed roast further by tying it with butcher's twine.

Tying your prime rib creates a more uniform shape and density along its length with three benefits:

More even cooking, with less chance of a gray ring around the inside edge of your holiday-table centerpiece.
A more even surface, allowing for better browning in the sear phase.
A better-looking finished product that is easier to slice.

Here are the steps to tying your roast...

Quick Tip: If you have a bone-in roast, tie between each of the bones and across the length of the roast. If you have a boneless roast, space your string every inch or so. Tie the strings taut to hold the roast as compact as possible.

How to Season Your Prime Rib

Prime rib doesn’t need a lot to dress it up, and will, in fact, do swimmingly with nothing but salt and pepper. You may be tempted to put all kinds of powerful spice rubs on your rib roast, especially if you are smoking the meat. But this premium cut of beef really shines with the classic flavors of salt and pepper.

Salt every surface well with Kosher salt. Don’t neglect the sides.
Allow the salt to penetrate the surface for 5 minutes.
Then apply freshly ground pepper to all surfaces. Look for about a 2 to 1 ratio, salt to pepper.

On the other hand, if you really want to dress it up and stay within a classic flavor palate, we recommend making a wet-rub of 3 cloves minced garlic, the minced leaves of 2 fresh rosemary sprigs, 1 teaspoon black pepper, 1.5 tablespoons dijon mustard, and 1/4 cup olive oil. Apply that paste after the sear.

Pre-chill Your Prime Rib Roast

There is sadly no agreement on the appropriateness of a counter-rest phase in preparing a prime rib roast. Some say to go right into the oven from the fridge, others say that a 2-hour rest on the counter is essential. All this ambiguity can be perplexing, so we tested it ourselves.

We wanted to determine the effects of various thermal preparations. We roasted 5 boneless prime rib roasts, carefully monitoring the thermal state of each roast through our various stages of preparation, cooking, and resting. For two of the prime ribs, we rested the meat on the counter prior to searing and roasting. For three prime ribs, we placed the meat in the freezer prior to searing and roasting. We were curious to see which of these methods produced the best results. We wanted a crispy outer crust but with no discernible gray ring between the seared crust and the rosy pink meat inside!

We found that the best results came from seasoning the roast, placing it in the freezer until the outside 1/4"" reached 30°F (-1°C), then moving right to the sear. This resulted in an almost undetectable gray ring on the roast.

SO, to properly prepare your Prime Rib Roast for searing without a resulting gray band...

Insert the probe of an alarm thermometer like ChefAlarm^® or RFX MEAT™ into the roast just below the surface.
Set your LOW alarm to 30°F (-1°C).
Place the seasoned, probed roast on a tray and put it in your freezer.
Keep the roast in the freezer until the low alarm sounds. This step should take about an hour.

Sear Your Prime Rib

Searing is essential for tasty prime rib. For one thing, searing the roast first will kill the surface bacteria, which is a nice touch, especially when you are roasting at lower temperatures. However, searing is important from a culinary standpoint, as well.

The sear gives us a bit of a nice crisp-meat crust, but more importantly, it creates a coating of Maillard-reaction browning all over the roast. This natural flavor enhancement is what makes prime rib delicious.

To sear your roast...

Preheat your skillet (cast iron is best) to 500°F (260°C) as measured with an infrared thermometer like our Industrial IR with Circle Laser (IRK-2).
Take your roast out of the freezer and remove the probes.
Sear the cold roast on all sides, giving each surface about 2 1/2 minutes against the pan, resulting in a ""nicely browned"" exterior. Don't neglect the ends.

How to Cook a Perfect Prime Rib Roast:

Preheat your oven or smoker to 225°F (107°C). Directly after searing your Prime Rib roast...

Place the tip of your alarm thermometer probe as near the physical center of the roast as you can.
Set the HIGH alarm to 125°F (52°C) on your alarm thermometer, like RFX MEAT™ or ChefAlarm for a perfectly pink Medium-Rare, or 130°F (54°C) for Medium doneness.
Place the roast on a shallow baking tray to allow the hot air of the oven to circulate around as much of the roast as possible while it cooks. A deep roasting pan prevents hot air from getting to the bottom of the roast, creating uneven cooking.

Because a prime rib Roast is such a large cut of meat, it will experience some real Carryover Cooking (from 5-8°F [2-4°C] depending upon the size of the roast) while it rests. Your serving temperature should end up being around 130-134°F (55-57°C) throughout the roast which is just right!

Note that you really should cook such an expensive roast to Medium Rare to experience all of the beefy goodness you paid for. Normally, those who like a little darker brown on their portion (like the children in the room) can pull from the end slices. If you DO want to cook to medium, however, you can add an additional 5°F (2°C) or even—dare we say it—10°F (6°C) to your pull temp. That means pulling your roast near 130°F (55°C) or 135°F (58°C) and finishing after the rest with a final internal temperature 135-144°F (58-62°C).

Advantages of chilling and slow cooking—enzymatic action

The combination of the freezer pre-chill and low-temp cooking provides us with a thermal advantage that goes beyond ""just"" perfect edge-to-edge pinkness. It actually makes the roast more tender.

Meat naturally contains enzymes that break proteins down and create a more tender product. [footnote]That's what happens in the aging process.[/footnote] Those enzymes are more active at higher temperatures, up to a certain point. Calpains drop off around 105°F (40°C) and cathepsins stop working at about 122°F (50°C). The longer we can hover in a range below these temperatures, but still warm enough to be cooking, the more tender our roast will be. (See Harold McGee's On Food and Cooking, pg 144.)

When we tested the various methods, we found that our freezer method provided more tenderization time.

The counter-rested roast spent just 24 minutes within the range of double enzyme activity, and 113 minutes with any activity at all.
The freezer-rested roast spent 35 minutes in the double-enzyme zone, maintaining a single enzyme action for the entire length of the cook—137 minutes.

With 11 extra minutes of double enzymes and 24 extra minutes of single enzyme action, the freezer-rested roast will have an enzymatic advantage in tenderness over the counter-rested roast. an enzymatic advantage in tenderness over the counter-rested roast.

Prime Rib Internal Temp: How to Know When Your Roast is Done Cooking

Using a leave-in probe thermometer like ChefAlarm or RFX™ Wireless Meat Thermometer is important for making sure you don't accidentally overshoot your target doneness temperature, but a probe that is not placed 100% correctly in the meat will also give you bad info about doneness. If the probe is too close to the surface, you'll have colder meat deeper in the center. That's why it's important to also verify the doneness of the roast with an accurate instant-read thermometer like Thermapen^® ONE.

When your ChefAlarm or RFX sounds...

Insert the probe tip of your instant-read thermometer, like Thermapen ONE, deep into the meat.
As you pull it up slowly through the roast, look for the lowest temperature you see. Meat is only as done as its least-done part!
If you find a lower temperature than the one displayed on your leave-in thermometer, move the leave-in probe to the cooler spot and continue cooking. If you don't find any lower temps, you're good to move to the resting stage.

And, just in case you prefer a different doneness temperature, here is a helpful prime rib doneness temperature chart as a downloadable image...

Rest Your Cooked Prime Rib:

Once your roast reaches 125°F (52°C) for Medium Rare, or 130°F (54°C) for Medium, and you verify its temperature with Thermapen ONE, remove it from the oven. Then tent it loosely with aluminum foil to rest. All meats should be rested before cutting and serving them. The rest period allows for temperature gradients in the meat to even out, slowly cooling the exterior while the interior meat continues to rise in temperature.

We did some tests on this and found that during the rest period, our exterior temperature dropped while the interior temperatures continued to rise slightly. Perfect.

How to Carve Your Prime Rib Roast

How you choose to carve your meat is up to you, but there are two—rather obvious—things that we want to point out...

Take off all the string you used to tie the roast up! No one wants to find a piece of cotton butcher's twine caught in their teeth during a delicious dinner.
Slice perpendicular to the cylinder. Don't carve down the length of the roast...it will not be good!

Those two basics aside, thin slices or fat slabs are your prerogative. Use a sharp knife and go for it.

Other Considerations:

What About Reverse Searing?

One of the appealing features of a prime rib is the salty, seasoned, beefy outer layer. Many methods include an instruction to reverse sear (sear after cooking) your roast to increase the crispiness. We wanted to keep the flavor and food safety advantages of pre-searing but also wanted to see if a final sear could give us just one little bit of extra enjoyment. So, we cooked another rib roast. For this one, we set our ChefAlarm to 115°F (46.1°C) so that we would be able to move the meat to a hot oven with thermal room to spare. As the roast approached pull temp, we preheated a second oven to 500°F (260°C).

When the alarm sounded, we reset it to 120°F (49°C) and moved the roast to the hot oven. The roast started to sizzle and sing almost immediately. It became steadily more brown and crisp on the outside. When we reached the next alarm point (set lower to account for the increased oven heat that would drive more carryover cooking), we removed the roast, let it rest, cut into it, and were disappointed to find a very noticeable gray ring, up to 1"" thick. In the end, the thicker crust that we got from the final sear was not worth the vast swaths of rosy pink meat that were lost.

We recommend a low, slow cook preceded by a good sear. Whatever crust you may get from the final sear is just not worth the risk to the rest of this exquisite cut of meat. And with the freezer method, you can get a harder sear without worrying about a gray ring from the beginning.