How anticipate how much food to have?

Any advice as to how to plan as far as how much food to bring with you to a fair or festival?  New to the business.  Is there a rule of thumb?
 
Thanks

one thing I have learned regarding planning on this site is
"The best laid plans of mice and men"
Al

Where in NJ? Just Jersey Corn?

best I can tell you on est. for any event is ask promoter what the attendance is then divide by 1/2, add 2, carry the four and multiply by the force of wind going thru a ducks a$$ @ 43 m.ph. and you'll have what you need to bring give or take a hundred dogs. seriously tho ask around the locals I/e fire, police etc. to try to get accurate numbers and pray to the man above it don't rain !!.. good luck and may the force be with you!!

Just a bit of incite.  I cooked for a group at a bike fest of about 3500 people for one day and I used approximately 30 cases of burgers and about 25 cases of hot dogs and used about 100 cases of soda. plus buns and condiments.  Like everyone else said ask alot of questions.  It is hard to be exact but I would rather have some left over than run out.  Remember your reputation is out there.  My frst one this years is about 15K people and looking forward to it.
 
Ray & Carol
Chef Hog

jmorris1986

Any advice as to how to plan as far as how much food to bring with you to a fair or festival?  Is there a rule of thumb?

Our rule of thumb is to not bring more than we can put out. I don't care if we are the only food vendors and there are 60K people there. We can only put out X amount of product per hour, running at full speed. It helps to know how much you can put out in an hours time. We don't over buy now. We know the max amount we can make at an event (Max food output X event hours) so that means we know how much we have to sell to cover entry fees/travel costs before we start making a profit. 
 
Others think differently and base on attendance. We don't because event promoter lie (99.999% of the time) about attendance.

Fairs and Festivals.  Willing to travel.  We may do more than just corn.