Hi and welcome. This site has a vast wealth of info. I don't know how much cake baking you do but I just downloaded the most awesome app called Tiered Caker. You plug in the number of servings and it will tell you the size pans based on shape and serving size whether it be party, wedding or custom. It has been the best app I have ever purchased! I haven't been doing this long enough to know without having to look it up every time. This is so fast and easy!