Cake Pan Conversion Calculator
This cake pan conversion calculator resizes any baking recipe when you switch pans — round, square or rectangular. It compares pan areas (or volumes) and applies the conversion factor to your ingredients, never to the baking time.
Same unit as the displayed result
Calculated results
Do not apply this coefficient to the baking time: it depends on the batter depth, the oven and the recipe.
Method and limits
How to use this calculator
Start with the original pan: its shape and internal dimensions — diameter for a round pan, side for a square, width and length for a rectangle — then its usable height. Enter the target pan the same way. Pick the conversion mode: area ratio for the same batter depth, or volume ratio to keep the same fill level. Finally enter an ingredient and its original quantity to get the adjusted amount.
With equal heights, the factor is the ratio of surfaces: k_A = A_target / A_original. When fill heights differ, volume mode uses k_V = (A_target × h_target) / (A_original × h_original). These factors imply no linear adjustment of the baking time.
Areas and volumes: the geometry of the math
A round pan's area is A = π·d²/4; a square or rectangle's is A = width × length. The default factor is the area ratio k_A = A_target / A_original: going from a 20 cm (8-inch) round pan to a 24 cm (9.5-inch) round one gives 24²/20² = 1.44 — 44% more ingredients. In volume mode, k_V = (A_target × h_target) / (A_original × h_original) preserves the fill level. Zero or negative dimensions block the calculation, and a factor below 0.25 or above 4 triggers an extreme-adjustment warning.
Proportional quantities and their limits
The factor applies linearly to ingredient quantities — flour, sugar, eggs, butter — to preserve the recipe's proportions. That linearity meets its limits with sensitive ingredients: baking powder reacts to batter depth, baking times lengthen with thickness, and some preparations (meringues, delicate sponge cakes) tolerate scaling poorly. Adjust the baking to your real oven and by eye, never by the factor.
Worked example
From a 20 cm (8-inch) round pan to a 24 cm (9.5-inch) round pan (same usable height): areas π×20²/4 ≈ 314.2 cm² and π×24²/4 ≈ 452.4 cm², factor 452.4 / 314.2 ≈ 1.44 — 144% of the original recipe. A recipe calling for 200 g (about 7 oz) of flour moves up to 288 g. Reproduce these values in the tool: you must get exactly the same results.
Assumptions and limits
The factor applies linearly to ingredient quantities to preserve the recipe's proportions; that linearity meets its limits with sensitive ingredients. Baking powder reacts to batter depth, baking times lengthen with thickness, and some preparations (meringues, delicate sponge cakes) tolerate scaling poorly. A factor below 0.25 or above 4 triggers an extreme-adjustment warning, and differing heights in area mode are flagged. Adjust the baking to your real oven and by eye, never by the factor.
Frequently asked questions
Limits of use