The number of portions given above, is only intended as a guide and based on the following dimensions.
Coffee size cake portions are 1" x 1" x height of the cake
Dessert size cake portions are 1" x 2" x height of the cake
However, actual quantities may vary, depending on the person cutting up your cake. If the cake is going to be cut by a professional caterer, he/she will more than likely get more serves out of the cakes than I have listed above.
Please contact me if you need assistance in deciding on cake sizes.