Baking Pan Size Converter
Original Pan Area
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New Pan Area
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Scale Factor
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Recipe Multiplier
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Converting Between Baking Pan Sizes
When you want to use a different pan size than a recipe calls for, you need to calculate the area ratio between the two pans. This calculator computes the area of both pans and gives you a scaling factor to multiply all ingredients by. For example, converting from a 9-inch round pan (63.6 sq in) to an 8-inch square pan (64 sq in) gives a scale factor of approximately 1.0 — nearly identical.
Round pan area is calculated as pi times radius squared. Square pan area is side times side. Rectangular pan area is length times width. The scale factor is simply the new pan area divided by the original pan area. Apply this ratio to every ingredient in the recipe.
When changing pan sizes significantly, you may need to adjust baking time and temperature. Larger, shallower pans cook faster and may need a slightly shorter baking time or lower temperature. Smaller, deeper pans take longer and may need to be baked at a slightly lower temperature to prevent the outside from overcooking before the center is done.
Frequently Asked Questions
Can I use a 9x13 pan instead of two 9-inch round pans?
A 9x13 pan has 117 sq in of area, while two 9-inch round pans total 127 sq in. The recipe will fit but the layer will be slightly thicker. Adjust baking time up by a few minutes.
How do I convert from round to square pans?
Multiply the round pan diameter by 0.9 to find the equivalent square pan size. For example, a 9-inch round pan is equivalent to an 8-inch square pan (9 x 0.9 = 8.1).
Do I need to adjust baking time when changing pan sizes?
Yes. Larger pans with thinner layers of batter cook faster, so reduce time by 5-10 minutes. Smaller pans with deeper batter need more time. Start checking 5-10 minutes early.
What if I double a recipe but keep the same pan size?
If you double a recipe, you need a pan with double the area, or use two pans. Doubling batter in the same pan will produce a much deeper cake that may not cook through properly.