Are your elderly people big eaters or small nibblers?

Rule of thumb is usually 1/4 - 1/3 lb. per person.

Also depends on how you make meatballs. Do you do all-meat, or use breadcrumbs or panko as a filler?

and what else will you be serving?

I also use the 1/4 lb. per person as a benchmark, if there are no fillers and you aren't serving them with something like spaghetti or in sandwiches. Of course, if you are serving them in pasta sauce or as sandwiches, you will need less, probably.

Annie

I just made the meatballs from the linked recipe, has significant filler, 3 pounds made 46 meatballs using a #16 disher (1/4 cup). So if I were using this recipe I’d multiply it by how many 2” meatballs the average person would eat.

http://colleen-slattery.blogspot.com/2012/03/classic-spaghetti-and-meatballs-for.html?m=1

It also depends on the fat content of the meat you are buying...80% lean beef is 20% fat and usually drains away.
I do a fair amount of cooking for church meals after a funeral....mostly elderly people and my rule of thumb for meatloaf is 5 people to a pound of 90% lean meat....but I also mix with egg bread crumbs and stuff like worchestershire and sometimes broth or tomato juice.
I would buy 8 pounds of meat.....and probably have some left over. Iw ould consider average serving to be 2 meatballs....some will eat 3 or 4 and some only 1.

Since it's elderly, I think Linda is right -- 2 per person. Younger people, I would do 3. Oh, and do they serve or do you serve them? That makes a difference too.

Well, depends on what's elderly! I am bad at figuring serving sizes even though I cook for a mixed group of 30-50 all the time. I hate running out more than anything so I just make a lot and have plates to send home with people. Meatballs keep so they won't go to waste.

Wow, those 2" meatballs are huge! Meatballs here are more like 1" :-)

I just had four for breakfast.

Since when would 30-50 be elderly? Yikes! I read that question and am thinking 70s and 80s.

After 60, I would expect the average portion size to be smaller, especially if these are residents in a facility or are generally less active. I would think at least 5 people per pound on average, but the recipe above with 46 meatballs from 3 lbs would be more like 7 people per pound if you use 2 meatballs per serving with a few left over. Another factor might be whether this is an event where folks might take leftovers with them --many will make a second meal if given the option.

If budget for this event is an issue, I think you can make as little as 5 lbs of relatively lean ground beef work. If having a generous amount of meatballs is more important, I'd look more towards 8 also. Meatballs freeze well, make good sandwiches as well as go with pasta and it's never a bad thing to have leftovers. I was raised to never run out, so if I were doing it, I might make 8-10 lbs worth and count on having some for us as well. As a practical matter, we buy ground meat at Costco and those large trays are and usually at least 5-6.5 lbs and often over 7, so as a practical matter, I'd probably look for the largest one and cook all of that or buy two smaller ones if I wanted to make some for us while I was at it.

sorry, 30-50 people.

It really is about the budget. I do add quick oats and good crusty bread soaked in milk, onions, mushrooms and celery, garlic, all pulverized in the Cuisinart till quite fine before mixing with the beef and eggs.

Personally I would go high like 10# minimum and hope for leftovers so all get what they want. They freeze well.

In Sauce and with noodles it will stretch much further.