Skip to Content

How many hours per pound to cook prime rib?

Cooking prime rib can seem intimidating for many home cooks. With its thick, rich meat and hefty price tag, you certainly don’t want to overcook this impressive cut of beef. Luckily, cooking prime rib is easier than you think. While there are some factors to consider like the size and thickness of your roast, following the basic rule of thumb for roasting times will ensure perfectly cooked prime rib every time.

How Many Hours Per Pound to Cook Prime Rib?

The general guideline for roasting prime rib is to allow about 13 minutes per pound for rare, 15 minutes per pound for medium rare, and 18 minutes per pound for medium. This timing is based on roasting in an oven at 350°F.

Here is a quick overview of roasting times per pound for prime rib:

Doneness Time per Pound
Rare 13 minutes
Medium Rare 15 minutes
Medium 18 minutes

So for example, a 5 pound prime rib roast should roast for about 65-75 minutes total:

– Rare: 65 minutes (13 min/lb x 5 lbs)
– Medium Rare: 75 minutes (15 min/lb x 5 lbs)
– Medium: 90 minutes (18 min/lb x 5 lbs)

You can see that the timing differences between doneness levels are relatively small. For a foolproof prime rib, we recommend roasting until medium rare and using a meat thermometer to check for your desired internal temperature.

Factors That Affect Roasting Time

While the minutes per pound method works well for most prime rib roasts, there are some factors that can slightly alter the total roasting time:

Thickness – Thicker roasts take more time than thinner ones. A roast that is 4-5 inches thick could take a little longer than the time per pound recommendation.

Bone-in vs Boneless – Bone-in rib roasts cook slightly faster than boneless roasts. The bones conduct heat faster to the center of the meat.

Oven Temperature – The 350°F oven temperature is ideal, but slight variances in older ovens can increase or decrease cook time.

Meat Temperature – Roasting prime rib straight from the fridge adds more time than bringing meat to room temp before cooking.

High Altitude – At high altitudes above 3000 feet, prime rib may cook faster and need time adjustments.

Choosing a Prime Rib Roast

When shopping for prime rib, here are a few tips for picking the best roast:

– Choose a roast with evenly distributed fat marbling for tenderness. Avoid excessive fatty areas.

– Whole rib roasts (bones attached) are best. The bones add flavor and make carving easier.

– Estimate 1 rib bone per person, and an extra bone. A 3-4 bone roast feeds 2-3 people.

– For thicker roasts, allow extra time. 4-5 inches is ideal. Thinner roasts can overcook quickly.

– Approximately 1 pound of bone-in prime rib per person is sufficient. Scale up for heartier appetites.

Preparing Prime Rib for the Oven

Proper prep ensures perfectly cooked prime rib:

– Choose a heavy roasting pan just larger than the roast. This promotes even cooking.

– Place roast bone-side down in pan. The bones conduct heat downward into the meat.

– Liberally coat the roast in olive oil. Salt and pepper generously. Herbs and garlic add nice flavor.

– Bring roast to room temp before cooking for more even cooking. Pull roast from fridge 1-2 hours before roasting.

– For crispy browned exterior, sear all sides in a hot pan before roasting. Use high heat on the stovetop.

– Insert a meat thermometer into the thickest part without touching the bone. This monitors doneness during roasting.

How to Roast Prime Rib for Perfect Results

Roasting prime rib is simple by following these steps:

– Preheat oven to 350°F. Place prepared roast bone-side down in roasting pan.

– Roast according to recommended time per pound for desired doneness. Rare roasts need about 13 minutes per pound.

– Monitor the meat thermometer after the minimum roast time passes. It should read:
– Rare: 120-125°F
– Medium Rare: 130-135°F
– Medium 140-145°F

– Once thermometer reaches 5° below target temp, remove roast from oven. The temp will rise 5-10° more degrees during resting.

– Lightly tent roast with foil and let rest 15-30 minutes before carving. This allows juices to redistribute.

– Carve between rib bones. Slice against the grain into 1/4 to 1/2 inch thick slices.

Tips for Perfectly Cooked Prime Rib Every Time

Follow these extra tips for prime rib success:

– Bring meat to room temp before roasting for more even cooking.

– Use a leave-in thermometer to monitor doneness easily. Ovenproof models available.

– Searing before roasting helps develop a delicious browned crust. Use very high heat.

– Roast at a low temp, 350°F. High heat can overcook the outer portions.

– Allow roast to rest after cooking. This finishes the cooking process gently.

– Check for doneness early and continue roasting if needed. You can always cook it more, but not less!

Common Prime Rib Roasting Mistakes

Avoid these common pitfalls when cooking prime rib:

– Roasting prime rib straight from the fridge. Letting it come to room temp prevents overdone edges.

– Cooking prime rib at too high of a temperature. Stick to 325-350°F for even cooking.

– Not using a meat thermometer. It’s impossible to test doneness visually on a thick roast.

– Cutting into the roast immediately. Resting allows juices to redistribute for tender, juicy meat.

– Overcooking through careless timing. Use a thermometer and check early for desired doneness.

– Roasting without a roasting rack. Elevating on a rack prevents steaming on the pan bottom.

Serving and Leftover Prime Rib

Cooked prime rib is delicious hot or cold:

– Slice thin and serve with natural au jus from the roasted pan for full flavor.

– Pair with hearty roasted vegetables, creamy scalloped potatoes or garlic mashed potatoes.

– Leftovers make amazing French Dip sandwiches with the pan drippings for dipping.

– Chilled prime rib makes excellent cold sliced sandwiches with horseradish sauce.

– Heat up slices in gravy or au jus for next-day roasted beef.


Cooking prime rib seems intimidating, but simply allow 13-18 minutes per pound for perfect doneness. Monitor temperature with a meat thermometer and rest the roast before slicing. With minimal hands-on time, you’ll have a restaurant-worthy standing rib roast. Now go impress your family and friends with melt-in-your-mouth prime rib!