How Much Prime Rib Per Person? (Portion Chart)

Wondering how much prime rib per person you need? Here is the short answer. Buy 1 pound of bone-in prime rib for each adult, or 1/2 to 3/4 pound of boneless. For a bone-in roast, that works out to one rib for every two people.

That rule covers a sit-down dinner with a few sides and hungry guests. The chart below does the math for any size table, from a dinner for four to a party of 20. After that, you will see when to buy more, when you can get away with less, and how long your roast needs in the oven.

The Quick Rule for Prime Rib Per Person

Prime rib is the most expensive thing on the holiday table, so you want to get the size right. Too small and somebody goes without seconds. Too big and you pay for beef you did not need. These four rules keep you out of trouble:

• Bone-in roast: 1 pound per adult, or one rib for every two adults.
• Boneless roast: 1/2 pound per adult for normal eaters, and 3/4 pound for big eaters.
• Buffet or lots of sides: Drop to about 3/4 pound bone-in or 1/2 pound boneless per adult.
• Kids: Count two kids under 12 as one adult.

All of these weights are raw weights. That is the number on the label when you buy the roast, so it is the only number you need at the store.

Prime Rib Portion Chart by Number of Guests

Find your guest count in the left column and read across. The boneless column gives a range. Use the low end for a meal with plenty of sides and the high end for a crowd of big eaters.

So how much prime rib for 10 adults? A 10-pound, five-rib roast, or 5 to 7 1/2 pounds of boneless. For 6 adults, buy a 6-pound, three-rib roast. For 12 adults, go with a 12-pound, six-rib roast. If your number falls between two sizes, round up. Nobody has ever been mad about leftover prime rib.

Bone-In vs. Boneless: Why the Numbers Change

A bone-in roast needs about twice the weight per person. The reason is simple. You pay for the whole roast, but you do not eat the whole roast.

First, the rib bones are part of that weight. Second, most people trim some of the fat cap on their plate. Third, every roast loses some weight in the oven as the fat melts and the juices cook off. Add those up, and a pound of raw bone-in roast lands at roughly half a pound of meat on the plate. That is a big, steakhouse-size serving.

A boneless roast skips the bone, so more of what you buy ends up on the fork. That is why 1/2 to 3/4 pound per person does the job.

So which one should you buy? The bones make a natural roasting rack, and they give you something to chew on after dinner. A boneless roast is easier to carve and easier to portion. Both taste great. If you want the full walk-through on the classic version, see our bone-in prime rib roast recipe.

How Many Ribs Do You Need?

Butchers often sell prime rib by the rib, not by the pound. That makes the math easy. One rib feeds two people.

A full prime rib has seven ribs and can weigh 15 pounds or more. Most home cooks buy a piece of it. A two-rib roast feeds four people. A three-rib or four-rib roast covers six to eight. Each rib adds about 2 pounds, sometimes a little more, so the rib count and the pound count usually agree.

One more thing to clear up. A rib roast, a standing rib roast, and a prime rib are all the same cut. The word "prime" in the name does not mean the beef is graded USDA Prime. Most prime rib roasts in stores are USDA Choice. A true USDA Prime rib roast has more marbling, and it costs more.

When to Buy More and When to Buy Less

The 1 pound rule is a starting point. Your menu and your guests can push it up or down.

Buy more if:

• You want leftovers. Add 1 to 2 pounds, or one extra rib.
• The roast is the star and the sides are light, like a salad and one vegetable.
• Your table is full of big eaters who will ask for a second slice.

Buy less if:

• You are serving a buffet with a second main dish, like ham or turkey.
• The meal has several courses, with appetizers first and dessert after.
• The sides are heavy. Mashed potatoes, rolls, and creamed spinach fill people up fast.
• A lot of your guests are kids or light eaters.

Sides are the cheapest way to stretch a roast. A couple of filling ones let you serve smaller slices without anyone noticing. Need ideas? Start with our list of side dishes for prime rib. A boat of au jus on the table helps too. It makes every slice feel like more.

How to Budget for Prime Rib

Prime rib is sold by the pound, so the math is quick. Multiply the pounds you need by the price per pound. A 10-pound roast costs ten times the per-pound price on the label.

Three things move that per-pound price:

• The grade. USDA Prime costs more than USDA Choice because it has more marbling.
• Bone-in or boneless. Boneless usually costs more per pound, but you need fewer pounds.
• Aging. Dry-aged roasts cost more than wet-aged roasts. Dry aging takes extra time, and the roast loses some weight along the way.

Prices at grocery stores and warehouse clubs change from week to week, so check the per-pound price before you shop. Whatever you pay, do not shave the size down to save a few dollars. Running out of the main dish is the one mistake you cannot fix at the table. If the budget is tight, add a side dish, not a smaller roast.

Steakhouse Shortcut: A Roast That Is Already Sized

Do not want to stand at the meat counter doing math? Our Bone-In Heart of Rib Roast takes the guesswork out. Check the weight when you order, then use the 1 pound rule to see how many guests it feeds.

You can pick Premium Angus, USDA Prime wet aged, or USDA Prime dry aged. It ships to your door, so the hardest part of your holiday dinner is done before you turn on the oven.

Cook Time by Roast Size

Once you know the size, you can plan your day. At 325 degrees F, a prime rib needs about 15 to 20 minutes per pound to reach medium rare. Use this chart to plan, not to decide when the roast is done. Your thermometer makes that call.

For medium rare, pull the roast when the center reads 120 to 125 degrees F. It keeps cooking as it rests and finishes around 130 to 135 degrees F. For medium, pull it at 130 degrees F. The USDA recommends cooking beef roasts to 145 degrees F with a 3-minute rest, so cook to the doneness that is right for your table.

Then let it rest for 30 minutes before you carve. A rested roast holds its juices, and that means more meat on the plate and less on the cutting board. For the full method, see our guide to cooking prime rib. If you have the time, slow roasting prime rib at a lower heat gives you even more pink from edge to edge. A good prime rib rub takes care of the crust.

Carve It So Everyone Gets a Fair Slice

How you carve decides how far the roast goes. If you cut between the bones, each slab is a huge steakhouse cut that can feed two. For a dinner party, take the bones off in one piece first. Then slice the meat about 1/2 inch thick.

Thinner slices let guests take one piece, then come back for another. The roast also looks bigger on the platter that way. Save the bones. Somebody at your table will want them.

What to Do With Leftovers

Buying a little extra is never a waste. Wrap leftover prime rib tightly and keep it in the fridge for 3 to 4 days. You can also freeze it for 2 to 3 months.

Reheat slices gently so they stay pink. A low oven and a splash of au jus or beef broth work better than a microwave. Then put the meat to work in sandwiches, hash, or tacos. We have a full list of ways to use leftover prime rib.

The Bottom Line

Buy 1 pound of bone-in prime rib per person, or 1/2 to 3/4 pound of boneless. Count one rib for every two guests. Round up if you want leftovers, and lean on the sides if you need to stretch it. Do that, and the only thing left to worry about is who gets the bones.