Costco does have them that big. We had one last week that served 25 hungry adults.

Hallah on Rockville Pike

We've bought our ribeye roasts (which is what a prime rib is) from Whole Foods and they have been amazing. I think they will remove the ribs for you, and then tie then on. That way you get the yummy taste of cooking on the bone, but it is a lot easier to carve. Joy of Cooking high heat method is a great recipe to follow.

My mom usually gets a 4 rib roast for 6-8 people with apps, salad, roasted potatoes, yorkshire pudding, brussels sprouts, and dessert. We are hearty eaters with at least half having seconds, and we still have leftovers every year.

If bone in, around 3/4 lb per person, or two people per rib, is standard. You could probably buy smaller if you're confident the little kids won't eat much.

Anonymous wrote:Harris Teeter will order them for you- and then you have it reserved. I did this 2 Christmas's ago. I'm guessing other grocery stores will do this as well.
Note-- depending on what else you are having you may not need as much Prime Rib as you think. I had about 20 people and we had TONS leftover. I used a prime rib quantity buying guide that I think was really based on only eating meat, and maybe one side. For Christmas we probably had 7-8 sides.

OP here- what size do you think I would need? I think 15 adults/teens and 6 younger kids. Doubt the younger ones will eat much, if any.

Try Wagshalls in DC. Call them and they'll probably have it for you. They're not cheap, but the quality of their meat is awesome.

Or, Wegmans.

Harris Teeter will order them for you- and then you have it reserved. I did this 2 Christmas's ago. I'm guessing other grocery stores will do this as well.
Note-- depending on what else you are having you may not need as much Prime Rib as you think. I had about 20 people and we had TONS leftover. I used a prime rib quantity buying guide that I think was really based on only eating meat, and maybe one side. For Christmas we probably had 7-8 sides.

Costco might have them that big.

I feel ridiculous asking this, but it's something I have never noticed at the regular grocery stores. I need a REALLY big one, to feed about 20 or so. I'm in the Bethesda/Rockville area, if that helps.