If it’s baby backs, at least 4 ribs per person. I like the regular pork back ribs and then I cut them to make St. Louise style. In my opinion if you cook them right they are just as tender and there is a heck of a lot more meat on them. With those you can do 3 ribs per person and that’s a generous portion. My problem is I’m a HUGE meat eater and I can eat a full rack no problem and still pig out on sides. I’m not normal so I don’t think like a “normal” person would. If someone only gave me 4 little baby back ribs I would think it was the appetizer.