I have been asked to make a cake for a party. They are feeding 400-500 people. She says "I assume not all will eat cake. how much do you recommend?"

I'm not sure what to tell her. How many servings would you recommend?

Is it a party say that there will be lots of food and other desserts?

I'd make at least 400 servings, not everyone will eat the cake but others might be very happy to have a second piece and you make sure there is enough if everyone wants some.

Ask her how many servings she wants.

Your client should tell you how many servings she wants. You shouldn't have to figure it out.

So much depends on what else is being served at the party! If alcohol is being served, I was told by an experienced cake decorator to deduct up to 20%. Maybe plan for 350-400?

I agree, I would let the customer figure it out.....otherwise I would say "Cake for 500??...500 pieces it is!" After all you are trying to make a living. If she wants less I would let her tell you.

I agree - the client needs to be the one to guesstimate how much cake she needs. That way if the number doesn't turn out to be 'just right', she is the one on the hook - not you!

First, I agree with IHATEFONDANT, the client should tell you how many servings she wants, otherwise it might be a "potential uncomfortable situation" (a problem) for you, if there was too little cake, she might blame it on you.
Now, if it was YOUR party, I agree with GeminiRJ, I was also told once that if alcohol is being served (maybe an open bar) that people usually eat less. But if only a glass of wine will be served with dinner, I wouldn't consider that a whole lot of alcohol. So, in other words, if there is no alcohol I would do 350-400 servings and if there will be alcohol, I would do 300-350 servings. HTH and I didn't confuse you more. Good luck!!

It also may make a difference if this is a buffet (ie, go help yourself to cake) or a sit down and be served function. If they are serving the cake, you need enough to put out for everyone, even if not everyone eats it, plus some extra to spare, but if it is a "help yourself" function, you can get away with less.

I'd ask the person throwing the party how many servings they want, then put it in writing (including the dimensions of what you consider to be a serving size).

I still think it depends upon whether there will be other desserts there. I guess I think that maybe there should be one dessert per person, so if cake is the only dessert, then I would say it should be for 400-500.

Thank you all for you input! I have emailed her and asked what is being served. Then I'll give her my price per serving and let her choose what she wants.

I don't know if it helps, but I had a large wedding cake to do and the bride was concerned about having too much cake. She was figuring the guest list was about 400 so I made the cake for 375. I cut and served the cake and when I left there was half of the second to last tier left and about 3/4 of the bottom tier left. The bride said by the end of the night there was only about 1/2 of the bottom tier left! (It is the square wedding cake in my photos) So I would say do at least 425-450. You can always tell the client to give you a final count a couple weeks before if she is having people RSVP.
HTH,
HeatherMari