How to calculate baking time when you change pan sizes

By Kathleen Purvis

Q. How do you adjust a cake recipe if you want to use a different size pan, such as using a 13-by-9-inch pan or cupcakes instead of two or three round cake pans?

A. You don't need to change the recipe, but you do need to adjust the baking time. But first, you need to make sure volume of the batter will fit in the new pan.

There are charts of pan volumes in some baking books or on websites.

For a shortcut, remember that a 9-inch round cake pan holds about 6 cups (if the batter is 1 1/2 inches deep). A 13-by-9-inch pan holds 12 cups. And a standard cupcake pan, with 1/2 cup batter in each of six cups, holds 3 cups. So a two-layer cake batter should convert easily to 12 cupcakes or a sheet cake.

The trick after that is figuring out how to adjust the baking time. There is no hard and fast rule, so you'll have to rely on your senses and checking the cake for the usual signs of doneness, such as pulling away from the sides of the pan or springing back when you touch the center lightly.

In general, the 13-by-9-inch cake will take about 5 to 10 minutes less than the 9-inch layers. To be safe, start checking about 15 minutes before the time in the original recipe. Cupcakes usually take about half as long as a 9-inch round cake. If the cake called for 30 to 35 minutes of baking time, start checking the cupcakes after 15 minutes.

Making any change in baking is tricky, but most cake batters should adapt easily.