How Much Prime Rib You Need (For 5-100+ People)

Juicy, tender, and marbled with fat, prime rib claims the center stage for festive occasions for a good reason.

Served with potatoes or creamed greens, it’s almost impossible to resist. Everyone wants a slice or two (or three for me!) so you have to make sure you have enough to generously serve your guests. 

With everyone having varying appetites and expectations, well, herein lies the challenge: just how much prime rib do you really need per person?

We’ve got you covered.

Here’s how much prime rib you should serve per person and how much is actually needed for any size crowd, from 5, 10, 20, 50 and even 100 people. Plus we’ve added our own tips for preparing prime rib, the GrillSimply way.

Bada-bing bada-boom. With prime rib on the menu your guests are 30% more likely to remember the meal for the rest of their lives (totally made up).

But, you want to make sure they are going to remember it for the right reasons, and not for reasons like being served squiddly portions. 

Before we let you know exactly how much prime rib you’re going to need, there is one overarching rule. Always prepare more than you think you actually need. Believe me, it’s better than preparing less.

Now, taking into account that a prime rib may lose up to 15-30% of its weight while it cooks, we are going to be dealing with raw weights. It just makes things easier when it comes to preparing how much you need. 

Of course, you should also consider other factors like the age of your guests, the time of day, and the event itself.

With all of this in mind, the general rule of thumb for preparing prime rib is:

  • As the centerpiece of the meal: 1 pound of raw weight per person.
  • With 3+ sides or other meats: 0.5 pounds of raw weight per person.

How Many People Does One Prime Rib Roast Feed?

When you’re at the butcher and you’re eyeing up a stunning prime rib, you may be wondering: just how many people will that one roast actually feed?

Well, the easiest way is to ask the butcher how heavy it is, and apply the general rule of thumb of 1 pound of raw weight per person.

But, typically a four-bone prime rib roast will easily serve eight guests, with a bit spare for seconds, leftovers, or a taste test for yours truly.

How Much Prime Rib Is Needed For 5 People?

If it’s your turn to cook for the family or a small group of 5 people and you really want to impress them, look no further than prime rib.

For, five people you can get away with just cooking one small-to-medium sized prime rib. You’ll need:

  • As the centerpiece: 5 pounds of raw prime rib to serve 5 people, or one small-to-medium sized prime rib roast.

  • With 3+ sides or other meats: 2.5 pounds of raw prime rib will be enough to serve 5 people. You’ll still need to get one small prime rib of course, but you’ll guarantee leftovers!

How Much Prime Rib Is Needed For 10 People?

Preparing to feed 10 people is nothing to scoff at. The sight of their clean plates is worth it in my eyes!

Just be sure you’ve prepared enough meat and I’m sure there will be no complaining. For 10 people you’ll need:

  • As the centerpiece: 10 pounds of raw prime rib to serve 10 people. 1-2 medium-sized prime ribs will cover you here.

  • With 3+ sides or other meats: 5 pounds of raw prime rib will be enough to serve 5 people. You should only need one medium-sized prime rib.

How Much Prime Rib Is Needed For 20 People?

There is significantly more prep work needed between small groups and large groups. When you’re cooking for about 20 guests, it’s certainly not a small group.

To be sure everyone gets their share, make sure to prepare at least:

  • As the centerpiece: you’ll need at least 20 pounds of raw prime rib to serve 20 people, or between 2-4 prime rib roasts.

  • With 3+ sides or other meats: 10 pounds of raw prime rib will be enough to serve 20 people. You’ll either need one large prime rib roast, or two normal sized. 

How Much Prime Rib Is Needed For 50 People?

Alright, pressures on. Cooking for 50 people is no joke. Especially when you’re relying on a perfectly cooked prime rib as your centerpiece.

But, just like anything, the more you prepare for it the better it’s going to be. Ensure you’ve prepared at least:

  • As the centerpiece: 50 pounds of raw prime rib is needed to serve 50 guests. This is roughly 6-7 normal prime rib roasts.

  • With 3+ sides or other meats: You’ll need 25 pounds of raw prime rib for your 50 guests.

How Much Prime Rib Is Needed For 100 People?

Preparing to cook prime rib for 100 people? Well, they sound like some lucky 100 people – so long as you cook the prime rib right and have enough to go around.

When it comes to preparations, make sure you have at least:

  • As the centerpiece: 100 pounds of raw prime rib to serve 100 people. Yup, it’s a lot. You’ll need roughly 12, normal 8-pound prime ribs.

  • With 3+ sides or other meats: 50 pounds of raw prime rib will be enough to serve 50 people. A little less, but still a lot!

Big Boy Tips For Serving Prime Rib To A Crowd

Here at GrillSimply, we’re no stranger to catering to a crowd. In fact, our expertise is delicious barbecue and roast meats, From cooking pulled pork for a crowd to shredded chicken feasts, to preparing amazing beef tenderloin for 100 people. 

Drawing on our experience cooking brisket for a crowd, or preparing tri-tip roasts, here are some expert tips for preparing prime rib for your next event or get-together:

Dry Brine Your Prime Rib

Dry brining is the process where you apply a dry, salt layer to the entire outside of the meat and let it sit for 8 hours or overnight.

A waste of time? I think not.

Over time this salt draws out moisture from the meat, before having this same moisture and salt reabsorbed and redistributed all around the prime rib.

In turn, this makes your prime rib retain a significantly higher moisture content over the cook! 

For more info, here’s exactly why you should dry brine your prime rib and how to do it!

Keep It Warm

Keeping meats and dishes warm before serving is hardly an issue when you’re only trying to feed a handful of people.

But, if you’re serving  anywhere from 10+ you know how messy and uncoordinated things can get, trying to serve everyone at once.

So, while you plate up everything else, you can either:

  1. Allow the prime rib to rest, covered with foil for up to about 20-30 minutes.
  2. If you need more time, you can place the prime rib in the oven, covered with foil, at 140°F until you are ready to serve.

Either way, covering the prime rib with foil is a must, it simply locks in all the moisture and helps it retain heat too!

Slice Properly

Just like with any cut of beef, slicing it properly is key. But, it’s not just about the size of your slices, it’s also about slicing against the grain, making the pieces of prime rib that much more tender and succulent.

Here’s the best way to slice a standing rib roast.

  • Cut the meat from the rib bones in one piece, making sure to follow the bone’s contour. 
  • Lay the meat on its side and cut in between the bones to make individual ribs.
  • Slice the meat across the grain into your desired thickness. Traditionally, prime ribs have a thickness of between 1/2 to 3/4 inches.

To make it easier, here is a perfect example from Certified Angus of how to slice your prime ribs correctly:

Best Side Dishes For Prime Rib

Since prime rib is made for celebratory occasions. It should be served with equally mouth watering side dishes to complete the piece. 

Some of my favorites include: 

  • Roasted vegetables (allowing them to soak up the juices of the prime rib). From onions, bell peppers, broccoli, and more.
  • Buttery mashed potatoes
  • Cheesy baked asparagus
  • Garlic butter mushrooms 
  • Potatoes Au Gratin (thinly sliced potatoes with a layer of cream-butter-garlic)
  • Creamy potato salad
  • Roasted garlic-parsnip puree

Side dishes are a great way to balance out and compliment the flavors of the prime rib. They also make the meal much more filling and nutritious.

Time To Wash Up!

Three words for you. Plan, plan, plan. The most important thing to get right, even more than the cooking of the beef itself, is the portion size.

Remember, if it’s the centerpiece of your dish, make sure to prepare 1 pound of raw prime rib per person. Over the cooking process it will lose some of its weight, but should still allow a perfect serve per person, as well as a little extra for seconds or leftovers.

If you’re cooking prime rib as part of a larger celebration, with many other meats and dishes, then you can easily get away with only half a pound of prime rib per person!

Best of luck everyone – and save me a bite!

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