How do I convert a recipe to a different cake pan?

Work out the base area of each tin, then divide the new area by the original area to get a scaling factor, and multiply every ingredient by it. A round tin's area is pi times the radius squared; a rectangular tin's area is length times width. Going from a 20 cm to a 23 cm round tin gives a factor of about 1.32.

Do I need to change the baking time and temperature?

Keep the oven temperature the same, but expect the baking time to change because the batter depth changes. A larger, shallower cake bakes faster, while a smaller, deeper one takes longer, so start checking a bit earlier or later and use a skewer to test for doneness.

Can I convert between round and square pans?

Yes. Because the conversion is based on area, you can mix shapes freely: choose round or rectangular for each tin and enter its dimensions. As a rough rule of thumb, a square tin holds a little more than a round tin of the same nominal size, since the corners add area.

Cake Pan Converter

This cake pan converter lets you take a recipe written for one tin and rescale it for the tin you actually have, so you get the right cake depth and baking result instead of an overflowing pan or a thin, dry sponge. The trick is that a cake tin's capacity is set by the area of its base, not its diameter, and area grows with the square of the size, so a tin that looks only a little bigger can hold a lot more batter. The calculator compares the base area of your original tin with the base area of your new tin and gives you a single scaling factor. You multiply every ingredient by that factor, and the recipe fits the new pan at the same depth. It handles round and rectangular tins in any combination: pick the shape of each pan, enter the diameter for round tins or the length and width for rectangular ones, and add an ingredient amount to see it rescaled. Bakers use it to shrink a big celebration cake down to a family size, to scale up for a crowd, or to swap a round recipe into the square tin in the cupboard. Keep the oven temperature the same, but check the cake a little earlier or later than the original recipe, because changing the pan changes how deep the batter sits and therefore how long it takes to bake through.

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Original tin

Shape

Diameter (cm)

Length (cm)

Width (cm)

New tin

Shape

Diameter (cm)

Length (cm)

Width (cm)

Ingredient amount to rescale (grams or millilitres)

Diameter is used for round tins; length and width are used for rectangular tins.

×1.32

multiply each ingredient by this

Original pan area314 cm²

New pan area415 cm²

Scaled amount331 g

The new pan has 1.32 times the area of the original, so multiply every ingredient by 1.32: 250 g becomes 331 g.

Scales ingredient quantities by base area at the same depth. Keep the oven temperature the same and check for doneness a little earlier or later, since the batter depth changes.

How it works

A cake tin holds batter in proportion to its base area. A round tin's area is pi times the radius squared, where the radius is half the diameter, and a rectangular tin's area is its length times its width. The scaling factor is the new tin's area divided by the original tin's area. Multiply every ingredient, and the tin's greasing, by that factor and the batter sits at the same depth in the new pan. A factor above 1 means you are scaling up, and below 1 means scaling down.

Worked example

A recipe is written for a 20 cm round tin, whose area is pi times 10 squared, about 314 square centimetres. You want to bake it in a 23 cm round tin, whose area is pi times 11.5 squared, about 415 square centimetres. The factor is 415 divided by 314, roughly 1.32, so you multiply every ingredient by 1.32. A quantity of 250 grams of flour becomes about 331 grams. Because the new cake is wider and no deeper, start checking it for doneness a few minutes before the original recipe's time.

Related calculators

Cooking Measurement Converter: cups, grams, spoons.
Grams to Cups Converter: weight to volume.
Baker's Percentage Calculator: recipe ratios.
Area of a Circle Calculator: circle area.

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