How do I calculate an increase in pan sizes for a cake recipe? How do I figure out what to increase in a cake recipe for bigger pan sizes? I have a cake recipe that uses two 8-inch round pans; how would I change the recipe to accommodate one 10-inch and one 14-inch round cake pans?
Assuming the depths of the pans are all the same, then the volume will vary as the square of their linear dimensions: 


8^2 + 8^2 = 64 + 64 = 128
10^2 + 14^2 = 100 + 196 = 296
Ratio = 296/128 = 2.3125


Near enough, multiply original quantities by 2 1/3