Cake pan size converter

Recipes are written for a specific pan. Switch pans and the batter is suddenly too shallow or about to overflow. The fix is to scale the recipe by how much batter each pan holds, which for a standard pan depth comes down to the pan's area. The tool above compares the two pans and gives you the multiplier.

Multiply every ingredient by

0.79x

The new pan is narrower, so the batter will be deeper and bake slower. Fill it no more than two-thirds and check for doneness later.

Common pan swaps and their multipliers

Multiply every ingredient by the factor shown. Values assume a standard 2-inch pan depth:

  • 9-inch round to 8-inch round: about 0.79
  • 8-inch round to 9-inch round: about 1.27
  • 9-inch round to 9-inch square: about 1.27
  • 8-inch square to 9-inch square: about 1.27
  • 9-inch round to 9x13 rectangle: about 1.84
  • 8-inch square to 9x13 rectangle: about 1.83
  • Two 8-inch rounds to one 9x13: about 1.16
  • 9x13 rectangle to two 9-inch rounds: about 1.08 total

How the converter works

Cake batter fills a pan to a depth. If you keep the depth the same, the amount of batter a pan holds is just its area, the bottom surface. The tool calculates the area of both pans and divides them. That ratio is how much to scale every ingredient.

A round pan's area is pi times the radius squared. A square or rectangular pan's area is length times width. The tool already knows the area of each common pan, so you only pick the two pans; you do not measure anything.

Depth, and when to adjust the time

This works when both pans have the same depth, which is true for most standard cake pans at about 2 inches. If one pan is much deeper, the area comparison is still a good guide, but the deeper pan will hold more.

Changing pans changes the baking time. A wider, shallower layer of batter bakes faster; a narrower, deeper one bakes slower. After you scale the recipe, start checking for doneness earlier if the new pan is wider, and later if it is narrower.

Do not fill any cake pan more than about two-thirds full. If the multiplier would overfill the new pan, bake the extra batter as cupcakes instead of forcing it in.

Pan sizes in centimeters

Pan sizes outside the US are usually given in centimeters. A 9-inch pan is about 23 cm, an 8-inch pan is about 20 cm, and a 9x13-inch pan is about 23 by 33 cm. The area math is identical in either unit, so the multiplier the tool gives does not change.

Common pan conversion mistakes

  • Swapping pans without scaling the recipe. An 8-inch and a 9-inch round differ by about 27 percent in volume, the difference between a proper layer and a thin one.
  • Forgetting to adjust the baking time. A scaled recipe in a different-shaped pan bakes for a different length of time. Watch it; do not just trust the original time.
  • Overfilling the new pan. Keep cake batter to about two-thirds of the pan's depth. Bake any extra as cupcakes.
  • Assuming a round and a square of the same number match. A 9-inch square holds about 27 percent more than a 9-inch round.

FAQ

Can I use an 8-inch pan instead of a 9-inch pan?
Yes, but scale the recipe. An 8-inch round holds about 0.79 times what a 9-inch round holds, so the batter would be too deep otherwise. Use the calculator for the exact multiplier.
How do I convert a round pan recipe to a square pan?
Compare the two pans' areas. A 9-inch square holds about 1.27 times a 9-inch round, so multiply the recipe by about 1.27. The calculator does this for you.
Does the pan change the baking time?
Yes. A wider, shallower pan bakes faster; a deeper one bakes slower. After scaling, start checking for doneness earlier or later depending on the new pan's shape.
How full should I fill a cake pan?
About two-thirds full. Cake batter rises, and an overfilled pan spills or domes badly. Bake extra batter as cupcakes.
Is a 9x13 pan the same as two 9-inch rounds?
Close. A 9x13 rectangle holds slightly less than two 9-inch rounds, about 92 percent. A recipe for a 9x13 fills two 9-inch rounds with a little room to spare.

Related tools and guides

¿Necesitas esta herramienta en español? Ver el conversor de tamaño de molde.

Where the multipliers come from

The multiplier is the ratio of the two pans' bottom areas, assuming equal depth. Area for a round pan is pi times radius squared; for a square or rectangular pan it is length times width. This is the standard method bakers use to move a recipe between pans.

Sources

Our numbers and methodology cross-reference these authorities:

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