How do you charge for hodos and buffets?

Ah yes, the "easy way" is to let someone else decide how much food. Unfortunately, it appears that only those with culinary skills can even come close

I rely on resources such as the British Catering Manual, Food For Fifty, etc., to get close guesses as well as experience and experience of other catering professionals.

running out of food is a nighmare and the worst of all worlds for a caterer.

per person is usually more lucrative, you could offer 5oz meat pp at carving station or have the option of 9oz or 12 oz pp @ $$$ or $$$$ additional cost.  Decided when setting menu.

They don't know how many are coming?  Well the burden is on them not you to decide how many guests they invited.   Then it comes back to you to sell them amounts that will insure they don't end up with no food after 10 minutes.

There are certainly ways to work open houses or open to the public events.....

I've been in the catering business for 20+ years, no matter how the food was sold, you can not run out of food, period.

In the end, all the guests that are at the event are your captive audience. If you sell food by the peice, the client is going to go the least expensive way to save money. all the guests are going to see it as you as the one that is running out of food, invited guests never see thier host as the one that didn't order enough food. It is not good to sell food by the peice or pound or each platter, because the client is always going to go the least expensive way. You will run out of food, period. It is always best to sell banquets "per person". Then you use your experience and proven formulas to calculate quantities. Every event is differant, you need to have experience in calculating quatities. I've been doing it for years with much success, but in my early days I had to learn from my mistakes. There is no book that you can buy that will define every event. It's called "the school of hard knocks".

And, it is always better to have left-overs then to run out. Because the if you cater a banquet for 100 people and run out of food, then you have 100 people dissapointed who are not going to come back for a new event.  It's better Always price by the head, and then make "enough" food.

I have to agree with cleverchef 100%.  Although I could come up with a response of my own, he/she said it best.