BakeSpan / Guide
Round to square: compare area, not width
An 8-inch circle and an 8-inch square are equally wide. They do not hold the same amount of batter at the same depth.
Start with the two base areas
The radius of an 8-inch round pan is 4 inches. Its base area is π × 4², approximately 50.2655 square inches. An 8-inch square has a base area of 8 × 8, or 64 square inches.
Factor = 64 / (π × 4²) = 4/π ≈ 1.273239545
For an original ingredient amount of 400 grams, the arithmetic gives about 509.30 grams. That is around 27.32% more, not an unchanged recipe. These are worked calculation values, not a tested cake recipe.
Going the other way
From the 8-inch square to the 8-inch round, invert the factor: π/4, approximately 0.785398163. Then 400 grams becomes about 314.16 grams. The direction of the conversion matters; the same percentage cannot simply be added in one direction and subtracted in the other.
Include every pan in the batch
For two identical original pans, double the original area before dividing. Do the same for multiple new pans. BakeSpan exposes a pan count on each side. The diagram shows one outline of each shape; the arithmetic includes the counts.
Geometry is not a baking guarantee
These calculations assume equal batter depth and straight sides. A new outline changes the relationship between the edges and the center. Pan material, oven behavior, and the recipe can also change the result. The tool does not calculate doneness, change oven temperature, or supply a reliable new baking time.
Further reading: Calculation method, sources, and limitations. These examples are arithmetic explanations, not tested recipes.