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Dec 23, 2008 06:42 AM

Split 18 lb rib roast or cook whole?

I am making a 18 lb standing rib roast for Christmas Eve dinner. Wondering if I should split into 2 more manageable pieces for quicker cooking or leave whole? Any ideas how long a 18 pounder would take if I choose to go that path?


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  1. Can you get the beast in the oven without whacking it?

    9 Replies
    1. re: sarge

      That's my question too. If you can get the whole thing in the oven, I say leave it whole.

      Once you get to a certain size it won't really matter if you cut it in half or not. Just because it weighs more as a single item doesn't necessarily meat it will cook in miraculously shorter time if you chop it in half. You're not adding any distance between the outside and the inside of the meat by adding pounds (compared to say a turkey), you're simply adding length to the item.

      With that said, you might want 2 separate rib roasts so you can have one on one end of the table and one on another end.

      Please, please, PLEEEASE use a probe thermometer for this venture. I assume you've spent well over $100 for this cut of meat and it would be absolutely and completely disastrous if you over cooked it. A probe thermometer will guarantee that the the item won't over cook in any way. It is well worth an extra $20 to get one of these thermometers; consider it a present to yourself!

      The cooking time will vary greatly depending on how hot your oven temp is. I suggest a lower temperature (usually less than 300 F) for the majority of the cooking time. You will end up with a more tender cut of meat and a more evenly cooked item as a result.

      1. re: HaagenDazs

        Unfortunately, I do not have the roast in my possession, its at my parents' place. I had my dad take a measurement and it look like its 17 inches long. My roasting pan, as it turns out, is only 16.5 inches long. I may have to split into two no matter what! Maybe take a few ribs off one end for the people that cant stand the sight of rare meat, and leave 14 inches for the rest of us? obviously, the smaller piece will cook in a shorter amount of time.

        I do have a probe thermometer, actually I will be using a couple.

        Also, would anyone suggest using convection bake?

        For sure I will have the roast out of the oven at least 2 hours prior.

        1. re: nielubow

          If you're going to cut it, I say cut it truly in half. I wouldn't complicate things by making larger and smaller pieces with different cooking times but that's just me.

          It sounds like you've got the thing under control so you know that the end pieces are going to be more well done anyway. Convection is great for items like this, I think. As with anything cooked by convection, watch that browning!

          1. re: nielubow

            Just did a 15 1/2 lb prime rib over the weekend on Convection roast and it was perfect. If you are using convection, no need to start out high like others suggest....convection will take care of the browning.

            1. re: ammel_99

              Definitely use a temperature probe. Did a 24 pound turkey set at Convection, and it was done in half the time that the turkey packaging called for (non convection oven).

                1. re: itryalot

                  Convection roast at 350 and probe thermometer set to 118 degrees.

              1. re: nielubow

                Unfortunately, I do not have the roast in my possession, its at my parents' place. I had my dad take a measurement and it look like its 17 inches long. My roasting pan, as it turns out, is only 16.5 inches long. I may have to split into two no matter what! Maybe take a few ribs off one end for the people that cant stand the sight of rare meat, and leave 14 inches for the rest of us? obviously, the smaller piece will cook in a shorter amount of time.

                My suggestion is to leave the roast whole and trim an inch or so to make it fit in the pan you have, rather than cutting it into two separate roasts. You can save the trimmed piece or pieces for steaks. There will be some shrinkage, so the roast will tighten up somewhat and fit in the pan better as it cooks.

                My only word of caution is to use a pan with sides in the two inch range and to roast on an elevated rack if possible for better circulation. If you you use a high sided pan the roast can look grayish roasting at a low temperature and if you do not sear or brown at a high temperature

            2. re: sarge

              Whole !! My X-mas rib roast is 13 - 15 most years, aways whole, not ice cold, semi room temp. 300 oven, about 2 1/2 hours most years. let it rest before cutting. Look at your guests eyes when you take that whopper out of the oven.

            3. Check this site:

              Cooking Time for Rare (120°


              (3) Ribs, 7 to 8 lbs. 15 minutes at 450°, Then 1 ¼ to 1 ½ hours at 325°
              (4) Ribs, 9 to 10 lbs. 15 minutes at 450°, Then 1 ½ to 2 hours at 325°
              (5) Ribs, 11 to 13 lbs. 15 minutes at 450°, Then 2 to 2 ½ hours at 325°
              (6) Ribs, 14 to 16 lbs. 15 minutes at 450° Then, 2 ¾ to 3 hours at 325°
              (7) Ribs, 16 to 18 lbs. 15 minutes at 450° Then, 3 to 3 ¾ hours at 325°

              3 Replies
              1. re: grampart

                Please be aware that guidelines like this are VERY broad approximations at best. A thermometer is the only way of ensuring correct temperature, and in my opinion a probe thermometer that constantly measures temperature is the best way to go so you don't overcook it.

                Another essential tip is to allow this to come to room temperature before cooking. Be aware this may take 2-4 hours.

                1. re: grampart

                  I used this chart to cook a 21-pound rib roast (I left it in one piece). Salt/pepper/garlic/onion rub and option (7): 15 minutes at 450 Then, 3-3/4 hour at 325. Internet temp was 120. Rested for at least 20 minutes and was medium-rare.

                2. I say keep it whole. It will make a fabulous presentation. I once cooked a 25 lb. standing rib roast in the Weber kettle. Talk about delicious!!

                  Personally, I think 450 is too high. I used to roast beef for 17 per lb. at 325*/ interior temp 125* for medium rare...15 min per lb for rare.

                  6 Replies
                  1. re: Gio

                    The thought behind high temps (whether at the beginning or the end) is for creating a browned crust, not cooking the meat by any appreciable measure. That's why there's "15 minutes" before the 450 degree instruction. ;-) I think it's a good idea to do at some point (like I said, beginning or end) during the cooking process. I opt for the beginning of cooking so you don't potentially overcook the outside.

                    1. re: HaagenDazs

                      HD: Many thanks for the explanation. Ever since DH had his heart by-pass we stopped red meat per the Dr.'s orders. So we don't do roast beast any more...sadly.

                      I really don't have any earth shattering tips... We used wood chips, a chimney starter, and pretty much it was straight forward grilling by the "Indirect" method. We also used to place the roast, seasoned with Kosher salt & freshly ground black pepper only, on a rack set in the same kind of roasting pan we use in the kitchen oven but that we just use in the Weber. That collected the drippings nicely. If you have a Weber, then you probably have their handy-dandy booklets which give tons of information. Oh and yes, the thermometer is a must.

                    2. re: Gio

                      Any tips on doing one in a kettle?

                      1. re: Gio

                        Wow! 25# on the Weber. Be still my heart. Could you handle a couple more the next time you do that??? Please :)

                        1. re: Gio

                          I have to cook 4 roasts ranging 13 to 16 lbs at the same time in same oven dinner is at 4 what time should I start the cooking will it take the same 3 to 4 hours or because of all the meat will it take a lot longer its for a fireman's bbenefiting need to do this right please help quick its tomorrow

                          1. re: Tammy322

                            You are going to need two ovens....and get them in the oven now....4-5 hours roasting time plus rest as long as possible.



                        2. I say keep it whole, unless you think yu will have trouble getting it in and out of the oven.

                          1. Now that you've determined you need to split the monster anyway, take advantage of the benefits. Now you will have twice as many end pieces, for those who like the crusty, heavily seasoned, more welldone portions. Definitely invest in a probe thermometer. Realize that even if both pieces are identically sized, they may cook at VERY different rates, depending on shape, structure, position in the pans and oven, and mere chance. Unless you are cooking very long and low (as many prime rib restaurants are able to do) your meat will coast up another 5 degrees or more after being removed from the oven. Resting time is crucial for juices to redistribute through the meat and not come spilling out onto the board. Enjoy -- as long as you pay attention to temperature, a standing rib roast is fairly simple and very delicious. Report back.

                            1 Reply
                            1. re: nosh

                              Well, its over. The 18.55 lb beast has been cooked and eaten! Here's how it happened....I let the roast sit at room temp for about 3 hours. I removed the boned then tied back on for easy removal and carving. Rubbed with 1.5 sticks of butter mixed with a lot of salt and pepper. Only problem here was that I always seem to have a problem with the butter having trouble adhering to the meat. I tried to dry the surface with paper towels hoping to get better sticking but its still difficult (any tips here?). I did the best I could and it seemed to create a nice crust. I dont think you can add too much salt to something like this!

                              Cooking method: Since the roast would not fit in a standard roasting pan, I used a 20-22 inch disposable aluminum pan, doubled up. Turns out it was the just the right size. 425 convection bake for 15 minutes. Then convection bake at 250 until the thermometer read 125 (I went a little higher than normal since my cooking temp was pretty low and did not expect too much carryover cooking). I would have cooked at 225 convection but the oven would not go so low. I used 2 insta-read thermometers about 8 inches apart near the center of the roast. The roast rested for about 40 minutes. Total cooking time was about 3 hours ( I didnt really pay attention to time, but the thermometer).

                              First few cuts came from the end for the babies :-). Then I went right for the center for the rest of us. Nearly the whole cross section of the meat was medium rare to rare with the exception of the outer 1/2 inch. It was a thing of beauty and it tasted great!

                              Thanks everyone for your help and have a pleasant holiday season!

                              BTW - one poster above assumed that I was female, while in fact I am a 30 year old guy. What was it about my original post that may have indicated otherwise:-)?