All depends on how far reaching the invites are. If they are all to people in her personal phone book then I would expect a very high turnout as much as 90%.

I especially think this could be a very high turnout because it is casual and aimed a certain community. People who knew her, but also know each other. That plus the keg, more like an Irish wake.....very high turnout!

It's really hard to estimate. Ask the person who knows the invitees best how likely they are to show up.
Remember that the leftovers can be eaten by the hosts or donated to a local shelter (well, not the keg!). That is a nice way to honor the deceased, too.

Thanks for the answers. I'll give her the information.

I think it depends a lot on the age of the invitees too. If there are a lot of older people invited and the party is at night, you may want to rule a bigger percentage out. I'm also wondering if maybe a percentage of people would think the deceased didn't want any type of shindig and may want to respect her wish by not attending.

Depending on your community size, etc. I'd probably guess lower than 90% just because people often have other engagements. I'd say 90% of those that rsvp as coming will actually end of coming (people or their kids get sick, Bob has an emergency at work, etc..)

I'd guess closer to 80% of those invited will attend (maybe even a little lower). Then again if the deceased was the principal of the school or very, very popular everyone could show up. Why don't you ask the caterer; they really should have a good guess with this kind of thing and know your community. If you guess too low, you may still be able to add a pasta or side dish to stretch the food out. Ask your caterer about your options.

My husband, the clergyman, told me that he has observed that the thing that REALLY makes a funeral big is if the deceased was young, even relatively young. Those funerals are huge, even bigger than the funerals of very prominent but very old people. I guess it is because there are so many more generations involved, and the deceased's siblings and parents' friends all come, too.

Remember that many people decide whether to come not based on their relationship to the deceased, but their relationship to the survivors (makes sense to me). I probably go to as many funerals/memorial services of people I didn't know at all, or barely knew (but I know their relatives), than those of people I did: last month, for example, I skipped my old boss's funeral (I didn't know his family at all), but I attended my friend's dad's (and I didn't know him at all). A single, childless, only child who didn't grow up in town -- even one who is very popular and prominent -- will have a smaller funeral than a member of an enormous family. So if Kathy's friend had a lot of siblings and children who live nearby, their friends and colleagues might come, too.

I think actually this applies more to a funeral than to a "celebration of life," though -- the latter seems to be more exclusively about the deceased, not the mourners.

Thanks for the time and thoughtfulness of the answers. I would think the caterer would have ideas of how much food to serve also but I guess mainly I'm trying to do my little bit to help out Kathy. I never met the woman who died.
Gellcom- It makes a lot of sense about who will attend based on family. I also come from a big family and saw what you were talking about Gellcom with my family when my parents died. When my Dad died many people came by the house and brought food and just dropped by. When my Mom died about 3 yrs later we just expected large amounts of food and people dropping by and it didn't happen and I think it was because people dropped by to console my Mother and when she died there was no one of that generation alive just us kids, if that makes sense.

To answer some of the other posters; Kathy is planning this to be like an Irish wake. She is doing it because she wants to honor her friend, Ann) and because she has hinted (without saying) that Anns' husband and son need it. Ann has a 17 yr old son who is graduating from HS next month.

I think most of the friends will be towards middle age and younger, Ann was in her mid 50s. The party will be on Sunday afternoon.
I don't think most of the people attending will necessarily know Anns wishes to not have a service.

Again, thanks to everyone.