Tomorrow I'll be going to a potluck that will be attended by around 20 people. I'm not good at cooking, so I'm planning on bringing something from a bakery.
What is the etiquette with regards to the amount of food/drinks you bring to potlucks? I wonder if what I bring needs to be enough to serve everyone, or if it would be okay if it's only enough to serve some big fraction of the people? If it helps, I'm in the US.
In general, if everyone brought a dish large enough to serve everyone, there would be far too much food. Suppose you expect 20 people and there are 4 "slots" to make a meal, consisting of an appetizer, an entrée, a side, and a dessert. If each person brings a dish for 20 people, everyone could be served with only 4 people bringing a dish. If all 20 people bring a dish each for 20 people, you'll have enough food to serve 100 people, not 20! No one wants to see 80% of the food at their event go uneaten, so everyone bringing a dish big enough for everyone is not ideal.
With this in mind, it's usually acceptable to make a dish that won't serve absolutely everyone, so long as there are other options in the same category. You wouldn't want to be in charge of the sole entrée item and arrive without enough to feed everyone, for example. If you're bringing one of many desserts, on the other hand, you should be OK bringing just one reasonably sized cake or batch of cookies, even if not everyone will get a piece.
I've personally had luck with this approach at a large work event of perhaps 75 people. It would have been unreasonable for everyone to make a dish to serve 75, so I made a dish that could serve perhaps a couple of dozen people, and it seemed many people did the same. There was still lots of leftover food overall, and although some of the most popular dishes were finished, it would have been very hard to predict which ones those would be in advance.
The basic principle is that total food brought equals (or slightly exceeds, to be safe) total food consumed. Thus, each person who will be eating a meal should bring at least one whole meal's "worth" of food, in terms of quantity, notwithstanding that the specific food by itself may not make a healthy or appetizing meal.
You can think about this in a couple of ways: enough of your food to fill a plate or two (since most people eat a plate or two of combined foods), or about 1000 calories of your food (since most people eat about that much for a hearty meal). The host/organizer is responsible for providing guidance to guests on what to bring, if it is considered important to have a balance between different types of food.
It is normal that your food will run out before everyone can try it -- especially in large potlucks, and especially if your food comes in a few large portions that each constitute a large fraction of a meal. If you want everyone to try your dish at a large gathering, consider pre-cutting into smaller portions as a hint, or making your dish some kind of sauce or topping where "a little goes a long way".
A source (from Canada, but very similar to US culture) says:
The standard rule is to bring enough to feed the people in your own group, plus a little extra...
There are several factors which could determine the answer:
There are far too many things in play. Hence... just ask. "Hey, I plan to bring ___. Not sure how much I should bring. What do you think?" Possibly including some of the above. e.g. "If I bring too much, do you want it for your freezer? Or should I aim to not have leftovers?"
Personal experience: I generally bring enough so that I can have an entire meal if no one brings anything I eat, plus enough for everyone else to try some. And I always ensure I can take it back home when I'm done (e.g. there's a fridge I can keep it after eating so it's not left sitting out).
Whenever there's something uncertain (e.g. 'does everyone eat pork?' 'is there a fridge?' 'Will you want the leftovers (so I know to bring it in a disposable container)?'), I simply ask.
Growing up in the Midwest, potluck dinners were a mainstay of my existence. They occurred after Lenten worship, Advent worship, and many Sunday festivals.
You aren't expected to feed everyone. That's just silly. Basically the expectation, at least where I grew up, was that you brought enough to feed your party and one or two more people. Some dishes go well, some don't - that's life.
No one will think less of you for not bringing enough. That's a much better thing than bringing nothing at all - that's just seen as being rude.
