Think you can't bake a cake if you don't have the right pan size? Think again. If you're making a cake and the recipe calls for a pan size you don't have, don't despair. Even the most ardent home baker—the one with a baking cabinet filled with pans of all sizes—runs into this situation now and again. You don't have to move on to another recipe that fits your pan size or run out to the nearest store that sells cake pans. (Whatever you do, don't use a flimsy aluminum pan from the grocery store; you're better off making do with any good-quality pan than trying to bake in something poorly constructed, even if it's the size your recipe calls for.) All it takes is a little adaptability. The following suggestions and guidelines will help you turn out a great cake, no matter what size pans you have at home. For the purpose of keeping things simple, our information applies to most layer cakes, sheet cakes, and loaves, but should not be used for cheesecakes, flourless cakes, and meringues.
Most cake recipes call for round, square, rectangle, or loaf -shaped pans. Rounds and squares are most often 8 or 9 inches, standard loaves are 9 by 5 or 8 ¼ by 4 inches, and rectangles are usually 13 by 9 or 10 by 15 inches. But what do you do if the recipe calls for 9-inch rounds and yours are 8 inches, or you want to bake a 13 x 9 inch sheet cake with a recipe that calls for a 9-inch square? Maybe you want to convert a triple layer cake into cupcakes? And how on earth do you bake a conventional cake recipe to work in an unconventional pan? These conversions are easier than you think.
It's All About Volume
Rather than focusing on the size of the pan, consider its volume, and adjust the batter accordingly. Many cake pans have sizes marked on the bottom, but not volume. To measure how much your cake pan will hold, fill it with water and then pour the water into a liquid measuring cup. (This helps if you're baking a recipe in a whimsical shape like a princess, a battleship, or something much more elaborate.) Bear in mind that the batter should only fill the pan by one half to two thirds. With that in mind, you'll find that an eight-inch cake pan has a volume of eight ounces, and takes about six cups of batter.
Measuring batter by cups can be messy. Many bakers prefer to weigh the batter for more accuracy. Others generally try to eyeball it, sticking to the two thirds of the pan depth rule of thumb. For layers, it matters most that the batter is even in each pan.
Here's a standard conversion for many basic cake recipes: A recipe that makes three eight-inch layers will make two nine-inch layers, one 13-by-9 inch sheet, and three to four dozen cupcakes.
Now That the Pan Is Sorted, Follow These Other Tips for Cake Success
First and foremost, avoid overfilling. Unless a recipe advises otherwise, fill cake pans (including muffin tins for cupcakes) about two-thirds full. If you have leftover batter, resist the urge to use it up by overfilling the pan. The deeper the cake batter, the longer it will take to bake, and if the proportions aren't right, the harder it will be to bake it to right texture. Instead, reserve leftovers until your cake has finished baking (most batters will keep well for a bit in the fridge) and then bake a few cupcakes with it.
We're also big proponents of setting a timer. Then, Start checking your cake about five to ten minutes before the recommended bake time. You might want to check even earlier if you've scaled up in size (a thinner batter will bake through more quickly.).
Last but not least, pay attention to other cues. Baking times are suggestions, and all kinds of factors can cause a cake recipe to take more or less time to cook through without drying out or burning. A cake tester inserted into the center of the cake is the best indicator, but check as well to see if the cake is pulling away from the side of the pan. You can also press lightly with your fingertip; if it's springy to the touch, it's done (depending on your recipe, of course).