get out of a Wiltom #1 shaped pan?

Sorry I don't have this pan so I couldn't answer the question for you but I think that these are usually done as single layer cakes and are not too big. How many people were you thinking of using this for? If you need a lot of servings perhaps you could put it on top of a sheet cake?

Or maybe you can measure (by using water) how much batter will be used for the cake and then try to determine it that way????? (Just a thought)

Does the insert give any clues?

Hopefully someone who has used this pan will be able to give you a better answer!

Yep, the water will work great. Fill a pan you already know the servings for, like a 6" round, and then see how many of that measurement will fill the questioned pan. easy!

Yes, you can measure it and judge that way. Another thing to consider is how big you will be cutting your pieces. Just look at it and pretend you are cutting it and see how many you come up with. HTH