How to Adjust a Baking Recipe for a Different Pan
How to compare pan sizes, scale the batter so it bakes the way the recipe intended, and adjust the time and temperature when you can't.
Compare Area, Not Just the Number on the Pan
Most cakes and bars bake best when the batter is about as deep as the recipe intended. Batter depth depends on the pan's area, so that's what you need to compare.
- Round pan: area = 3.14 × (diameter ÷ 2)². An 8-inch round is 50.3 sq in; a 9-inch round is 63.6 sq in.
- Square pan: side × side. An 8-inch square is 64 sq in; a 9-inch square is 81 sq in.
- Rectangular pan: length × width. A 9 x 13-inch pan is 117 sq in.
Scale the Batter to Fit
To keep the batter the same depth, multiply the recipe by the ratio of the two areas: new pan area ÷ original pan area.
Example: the recipe is for one 8-inch round (50.3 sq in), and you have a 9-inch round (63.6 sq in). 63.6 ÷ 50.3 = 1.26, so multiply every ingredient by about 1.25. For eggs, round to the nearest whole egg, or weigh beaten egg for accuracy.
With the batter at the same depth, the bake time stays close to the original. A slightly larger pan may need a few minutes more, so test rather than trusting the clock.
If You Don't Scale the Batter
Sometimes it's easier to use the recipe as written. Then the batter will be thinner or thicker than intended:
- Bigger pan, thinner layer: it bakes faster. Start checking about a quarter of the way before the recipe's time. The cake will be flatter but fine.
- Smaller pan, deeper layer: it takes longer. Lower the oven by about 25°F (15°C) so the top and edges don't over-brown before the middle sets, and start checking at the recipe's time.
- Never fill a cake pan more than about two-thirds full, or the batter may overflow as it rises.
Pan Material and Shape Matter Too
Dark metal pans absorb more heat and brown faster than light, shiny ones; some manufacturers suggest lowering the oven by 25°F for dark pans. Glass heats more slowly but holds heat longer, which can over-brown the bottom and edges of cakes. Many bakers lower the temperature by 25°F when using glass, too.
Tube and Bundt pans bake more evenly because heat reaches the batter from the center as well. When moving a recipe into a Bundt pan, compare the pans' volumes (fill each with water, a cup at a time) rather than their areas.
How to Tell It's Done
Because time is only a guide when you change pans, use a doneness test:
- A toothpick or skewer in the center comes out clean or with a few moist crumbs, not wet batter.
- The top springs back when pressed lightly, and the edges are starting to pull away from the pan.
- Most butter and sponge cakes read about 200-210°F (93-99°C) in the center on an instant-read thermometer.
Common questions
Can I bake an 8-inch round cake recipe in an 8-inch square pan?
Yes, but the square pan is about 27% bigger, so the cake will be thinner and bake faster. Multiply the recipe by about 1.25, or start checking 5-10 minutes early.
What pan equals a 9 x 13?
Two 8-inch square pans (128 sq in total) or two 9-inch rounds (127 sq in total) are close matches.