Newbie here both to the forums and baking for money LOL

I have been commissioned to make a cake for "approximately 40-60 people". The party is a 50th birthday and the wife of the birthday boy has requested this. She is uncertain on the numbers but thinks 40 will be enough as lots of people don't eat cake.

I'm charging for the cake and not for servings as I won't be cutting the cake so can't guarantee the number of servings.

Considering the party is at home and she or her mom will probably cut the cake, would you go with a square cake or a round cake?

(it's a simple cake as far as decorations go: Chocolate cake torted into 4 layers, filled with ganache and caramel and covered in ganache and almonds)

Also would you use 10 or 12" round or 8 or 10 " square?

Hi Newbie,
An 8 square serves 32, and a 10 square serves 50 slices.
The squares and sheet pans are easy to figure out the servings. Take the 8" square, now take 8 times 8 = 64 divide by 2 = 32, this is for 1x2x4 inch tall slice. I don't do party sizes. A serving of cake is a serving of cake
A 10 round serves 39. Ask her which one she wants. I also explain a square cake is easier for most people to cut.
Then charge her by the slice/serving.

It doesn't matter who cuts it. You can't garantee the amount of servings on any cake. You then explain to the customer, this 10 inch sq cake will serve 50, 1 by 2 inch slices. It will serve less if you cut the pieces bigger!
Sorry, I am in a mood today
You can always give your customer a diagram on how to cut the cake!!! Have fun!!!! That is the most important part!