The cooking time for prime rib depends on the size of the roast and the desired level of doneness. Here are the general guidelines:

• Initial high-temperature sear: Start by roasting the prime rib at 500°F for about 15 to 25 minutes to develop a crust and color on the outside.
• Lower temperature roasting: After the sear, reduce the oven temperature to 325°F (or sometimes 300°F) and continue roasting.
• Cooking time per pound:
  • For rare, cook about 10-12 minutes per pound.
  • For medium-rare, cook about 13-14 minutes per pound.
  • For medium, cook about 14-15 minutes per pound.
• Internal temperature targets:
  • Rare: 115-120°F
  • Medium-rare: 125-130°F
  • Medium: 135-140°F
  • Medium-well: 145-150°F
• Resting: Remove the roast from the oven when it is 5-10 degrees below your target temperature, then tent with foil and let it rest for about 30 minutes. The internal temperature will rise during this time, and resting allows juices to redistribute

For example, a 5-pound prime rib cooked to medium-rare would take roughly 15 minutes at 500°F, then about 65-70 minutes at 325°F (13-14 minutes per pound), plus resting time. Other methods like sous vide or smoking vary in time significantly but generally take several hours at lower temperatures

. Using a meat thermometer is essential to ensure perfect doneness and avoid overcooking