Cooking a Prime Rib at 280 degrees for inside temp 120. How long will it take to cook?

Sharon G: Cooking a Prime Rib at 280 degrees for inside temp 120. How long will it take to cook?
I have a prime rib that is 10 3/4 pound with 5 or 6 ribs. What I’m trying to figure out is cooking at 280 degrees and to be done at 120 degrees how many hours will it take.
I am useing a digital thermometer

Answers and Views:

Answer by Chris G
Those kinds of things will not deal with time, but the JUST the temperature. I recommend just getting a meat thermometer from BedBath and Beyond, Walmart, or some cooking supplier.

And besides, 120 is not enough to kill all the bacteria if there is any. I think 135 is the right temperature to kill all the germs.

But it just comes down to using an internal thermometer. Sorry that there isn’t a time.

Answer by doug k
I agree with the other person that you really need a meat thermometer to do this. I DON’T agree that you need to cook a prime rib to 135 degrees. Go to 120 degrees like you are planning. Let the meat set at least 10 minutes after you take it out of the oven. This allows the juices to redistribute so the meat will be nice and moist and all the juice wont run out immediately when you cut it. While it rests, the temperature will rise another 5 to 10 degrees. I like prime rib at 125 degrees. This will be between rare and medium rare. If you have someone who doesn’t like it that rare, give them meat from the ends, which will be more done. If I was cooking it, I would plan on it taking about 2 1/2 hours. To make the outside nicely browned, I would start in a hot oven (400 to 450 degrees) and then immediately reduce the heat for the rest of the cooking time.