Swap 8x8, 9x13, round and loaf pans: how much to scale the recipe.
How the Pan Size Conversion works
Enter the pan the recipe is written for and the pan you have (round, square or rectangular, and how many), and get the number to multiply the recipe by, so the batter comes out as deep as the recipe intended.
The factor is the ratio of the base areas: round = π × (diameter ÷ 2)², square = side², rectangle = width × length. A 9-inch round is 63.6 sq in, an 8x8 is 64 and a 9x13 is 117.
Example: an 8x8 recipe in a 9x13 pan: 117 ÷ 64 = 1.83, so make about 1 3/4 times the recipe. Two 9-inch rounds (127.2 sq in) hold almost exactly a 9x13 recipe (× 0.92).
Frequently asked questions
Can I bake a 9x13 recipe in two 9-inch round pans?
Yes: two 9-inch rounds are 127.2 sq in against 117 sq in for a 9x13, so the batter comes out about 8 % thinner. Start checking for doneness a few minutes early.
How do I convert an 8x8 recipe to a 9x13 pan?
Multiply the recipe by 117 ÷ 64 = 1.83, about 1 3/4 times.
Is an 8-inch round pan the same as an 8x8 square pan?
No: the 8-inch round is 50.3 sq in and the 8x8 square 64 sq in, so the square holds about 27 % more.
How big is a 9x5 loaf pan compared with an 8x4?
A 9x5 loaf pan is 45 sq in at the base and an 8x4 is 32 sq in, so the 9x5 takes about 1.4 times the batter. Loaf pans are deep, so compare the depth too.