If you prefer to roast your prime rib a bit “lower and slower” (at 300°) or want to roast it a bit more quickly (at 350°), ...

When ordering the rib from the butcher ask for a roast with the best marbling. Leave your roast out of the refrigerator long enough for it to be at room temperature. Preheat your oven to 500 degrees.

Roast the prime rib at 450°F (232°C) for 20-25 minutes to develop a golden, aromatic crust. Reduce the Temperature Lower the oven temperature to 325°F (163°C) and continue roasting.

With that in mind, assuming you’re starting with a prime rib roast that has an internal temperature of 38° (just out of the refrigerator), LaFrieda says the basic formula for perfect medium ...

If you prefer to roast your prime rib a bit “lower and slower” (at 300°) or want to roast it a bit more quickly (at 350°), here are additional formulas from LaFreida to help you estimate ...