How Long Does Prime Rib Take To Cook
Prime rib timing depends heavily on the roasting temperature you choose and the size of the bone-in cut. So, how long does prime rib take to cook? As a general rule, plan for 13 to 15 minutes per pound at 350°F (175°C) for a bone-in roast, but that number changes fast based on your method. Below you’ll find exact times, temps, and a simple plan for a perfect roast.
How Long Does Prime Rib Take To Cook
The short answer: a 5-pound bone-in prime rib takes about 1 hour 15 minutes to 1 hour 30 minutes at 350°F. A 10-pound roast takes roughly 2 hours 15 minutes to 2 hours 30 minutes. These times get you to medium-rare, which is 130°F to 135°F internal.
But time alone is not the best way to judge doneness. Always use a meat thermometer. Ovens run hot or cold, and the shape of the roast matters. A long, thin roast cooks faster than a short, thick one of the same weight.
Quick Timing Chart By Weight
- 3 pounds bone-in: 45 to 55 minutes at 350°F
- 5 pounds bone-in: 1 hour 15 minutes to 1 hour 30 minutes
- 7 pounds bone-in: 1 hour 45 minutes to 2 hours
- 10 pounds bone-in: 2 hours 15 minutes to 2 hours 30 minutes
- 12 pounds bone-in: 2 hours 45 minutes to 3 hours
These times are for a roast that starts at room temperature. If you take it straight from the fridge, add 20 to 30 minutes.
Timing At Different Oven Temperatures
The temperature you pick changes everything. There are three common methods, and each one has its own clock.
High Heat Then Low Heat (Restaurant Method)
Start at 450°F for 15 minutes to sear the outside. Then drop to 325°F for the rest of the cook. At 325°F, plan on 15 to 17 minutes per pound. This gives you a deep brown crust and a juicy center.
Low And Slow At 250°F
Some cooks swear by low heat. At 250°F, plan on 20 to 25 minutes per pound. A 5-pound roast could take 1 hour 40 minutes to over 2 hours. The upside is very even doneness from edge to center. The downside is a softer crust, so you may want a quick broil at the end.
Reverse Sear Method
Cook at 225°F to 250°F until the roast hits 115°F. Then rest it for 30 minutes. Finally, blast it at 500°F for 8 to 12 minutes. Total time runs about 2 to 3 hours for a 5-pound roast, but most of that is hands-off.
Internal Temperature Is The Real Answer
Forget the clock for a second. The thermometer tells the truth. Pull your roast at these temps for your desired doneness:
- Rare: 120°F to 125°F
- Medium-rare: 130°F to 135°F
- Medium: 140°F to 145°F
- Medium-well: 150°F to 155°F
- Well done: 160°F and up
Remember that carryover cooking raises the internal temp another 5°F to 10°F while the roast rests. So pull it 5 to 10 degrees before your target.
Step-By-Step Cooking Plan
- Take the roast out of the fridge 1 to 2 hours before cooking. This helps it cook evenly.
- Pat it dry and season generously with salt and pepper. Let it sit at room temp.
- Preheat your oven to 350°F (or your chosen method temp).
- Place the roast bone-side down in a roasting pan. No rack needed if the bones act as one.
- Insert a meat thermometer into the thickest part, away from bone and fat.
- Roast using the time per pound as a guide, but start checking 20 minutes early.
- Pull the roast when it hits 5 to 10 degrees below your target temp.
- Rest it loosely covered for 20 to 30 minutes. This step is not optional.
- Carve against the grain and serve.
Factors That Change Cooking Time
Bone-In Versus Boneless
Bone-in roasts take a bit longer per pound because the bones slow heat transfer. Boneless cooks faster, but it also dries out quicker. Add about 5 minutes per pound for bone-in.
Roast Shape And Size
A thick, compact roast takes longer than a long, flat one. Two 4-pound roasts cook faster than one 8-pound roast. If you can, choose a roast that is evenly shaped.
Oven Accuracy
Your oven dial may be off by 25°F or more. Use an oven thermometer to check. This one step prevents a lot of ruined dinners.
Starting Temperature
A cold roast from the fridge adds 20 to 30 minutes to the total. A room-temp roast cooks faster and more evenly. Plan ahead.
Common Mistakes To Avoid
- Relying only on time and never using a thermometer
- Skipping the rest period, which causes juice loss
- Cooking at high heat the whole time, which burns the outside
- Opening the oven often, which drops the temp
- Carving too soon after pulling from the oven
Follow the weight-based times as a starting point, but let your thermometer make the final call. A 5-pound bone-in prime rib at 350°F lands around 1 hour 15 minutes to 1 hour 30 minutes for medium-rare. Adjust for your oven, your method, and your guests’ preferred doneness. With a little practice, you will nail the timing every time.