Cooking your prime rib at a temp of 250°F?
Wondering how long you need to cook it to get it to your desired doneness?
Below you’ll see exactly how long you need to cook your prime rib.
How Long to Cook Prime Rib at 250°F per Pound for Medium
To get medium prime rib you need to cook it for 35 minutes per pound at 250°F
This level of doneness is what I usually go for.
As there is still a pink center and the fat has time to render.
However, not everyone what medium, so below you’ll see all the other timings
How Long to Cook Prime Rib at 250°F per Pound for Rare
To get a rare prime rib you need to cook it for 30 minutes per pound at 250°F.
How Long to Cook Prime Rib at 250°F per Pound for Well Done
To get a well-done prime rib you need to cook it for 45 minutes per pound at 250°F.
Example of Cooking an 8-Pound Rib Roast Medium
Let’s say your prime meat cuts weigh 8 pounds and you prefer medium doneness.
A 8-pound roast will take 280 minutes at 250°F. (4.5 hours)
Accurately Monitoring the Cooking Time
Now we know how to calculate the cooking time.
But how can we further ensure that we are accurate?
Know the Exact Weight
Make sure you know the exact weight of the rib roast.
This will be on the packaging if you got it in the store.
I recommend you buy fresh and free range from a butcher.
Always confirm the weight with them on purchase.
Note: You can always buy your prime rib and freeze it for later.
Meat Grading & Trimming the Fat Cap
Prime rib come from the rib on a cow, which is a primal cut. These cuts of meat that contain a high percentage of fat.
Which is not a bad thing and part of the reason it tastes so good!
Prime ribs are graded on the amount of intramuscular fat.
Which gives tastier juices and a rich flavor.
The subcutaneous fat (outside cap) can stop the meat proteins from cooking.
So you want to get it trimmed to 1/2 an inch.
This cut can be an expensive roast to cook.
Especially if you buy USDA choice prime-grade beef.
So do it right!
Bone-in or Bone-Out?
A boneless roast contains more meat per weight than a bone-in roast.
A bone-in roast may also take longer to cook than a boneless rib roast.
As the heat has to penetrate the rib bones.
Factor in whether or not you are cooking bone-in or out when estimating timings.
As this can affect your prime rib roast recipe.
By making the meat dry from overcooking.
As you didn’t factor in the weight of the bone.
Indirect or Direct Heat?
250°F is a low-medium temperature for cooking cuts of beef.
Which should be done with indirect heat for the delectable meat.
This will allow for the fat and connective tissue to render during the roasting time.
Resulting in tender muscle fibers (meat) and the reintroduction of natural juices.
Forming a Crust From the Fat Cap With Direct Heat
Remember that layer of fat on the cap?
A sign of perfectly executed rib roasts is a well-browned crust.
By pan-sealing the entire roast with a bit of kosher salt.
To develop an outer crust from the fat.
This locks in juices and removes surface moisture for your rib roast recipe.
For the ultimate roast beef-eating experience.
You can also try a reverse sear on the outer layer fat.
Which is the same as above, just after it has cooked through!
What Internal Cooking Temperature Does the Meat Need to Be?
Below is the temperature chart before the consumption of a rib of beef.
Based on the preferred levels of doneness.
Remember that the cooked temp of your meat can vary.
Based on things like a thicker crust, grade of beef, or pound of bone.
Internal Temperature Gradients for Doneness
Rare – 125°F on a meat thermomoeter.
Medium – 135°F on a meat thermometer.
Welldone – 155°F on a meat thermometer
Resting & Carryover Cooking Process
Cover with foil or butcher paper while resting. You can also place your prime rib in a cooler to rest it.
The internal temp will raise by about 10°F during this process.
Which is known as carryover cooking.
Remove from your hot oven or grill a little bit before your required perfect temperature.
Keep the meat thermometer in so you can monitor it while resting.
Letting the prime rib roast meat rest is an important part of the process.
Rest for 10 minutes per pound of meat.
Remove the aluminum foil or paper just minutes before carving.
Accurately Monitoring the Internal Temperature With a Meat Probe
Arguably the most important tool in all your cook time!
Have calibrated temperature probes to accurately monitor the internal temperature.
These are a type of digital thermometer you insert into the flesh during cooking.
They update you in real time for an accurate reading.
Temperature control is key for a successful cook.
Remember that these timings are estimations.
Knowing an exact cooking time is impossible.
So an instant-read thermometer is the most accurate and safe way.
To know the perfect doneness.
Optimum Temperature Ranges
The standard temperature range is 20°F above or below your set temperature.
This will depend on what you are using to cook the ribeye roast.
What Should I Use to Cook Prime Rib?
A convection oven or pellet smoker is best for prime rib.
Below are some tips for slow roasting and smoking on these at 250°F.
Just remember to consider the above factors.
So you can be confident when serving up a holiday dinner.
On a Pellet Smoker
A smoked prime rib roast is my favorite.
Set the temperature to 250°F.
While waiting for the temp, seal the fat for a delicious brown crust.
Think about the type of wood chips you want to use.
A pellet smoker will maintain a consistent temperature within 5-7 degrees.
Making it easier to calculate the cooking time for your favorite recipes.
Monitor the internal temperatures with the probe.
Cooking Tips for Side Dishes
What are you serving as a side with your rib roast?
Smoked baked potatoes covered with rosemary coarse sea salt?
With butter and crushed cloves of garlic on a baking tray?
Or roasted broccoli and green beans and creamy horseradish sauce.
Roasting in a Conventional Oven
Start warming a 250-degree oven set to fan mode.
While you wait for the oven temp you can start on that nice crisp-meat crust!
Put the roast on an oven rack or baking sheet.
This will catch the beef juices when cooking.
Then place it at the top of your preheated oven fat side up.
Be careful not to keep opening the door as this can drastically reduce the heat. If the prime rib is cooking to fast, reduce the temperature to 200°F.
Monitor the internal temperatures with an oven thermometer.
Note: Oven temperatures can jump around if you open the door.
Try to avoid doing so through the cooking process.
Author: Charlie Reeves
Hi, I’m Charlie, I am head taste tester at Simply Meat Smoking! I love it grilling, smoking, and getting out in the yard with the kids! The family also love to test all my recipes (especially my EXTRA CRISPY pulled pork, smoky pork loin, and ANY SEAFOOD I grill)
You will usually find me playing with the kids, perfecting my brisket bark, or sipping beers with boys around the fire. Can’t wait to share all my delicious smoking and grilling adventures with you!
You can read more on our About Us page.
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