20x8cm Delia Online Round Cake Tin, Loose Base"Over the years I have constantly had to re jig cake recipes because the required tin sizes were no longer available. And this is the predominant reason more often than not that cake recipes sometimes fail that is, you are simply not using the correct tin for the mixture. Let me explain the science. Sponge cakes go like this: mixtures containing 2 eggs and 115g each of flour, sugar and butter need 18cm tins, while 3 egg and 175g mixtures need 20cm