Home › Calculators › Pan Size Swap
Opens on Chapter 9’s example: A brownie recipe for an 8 × 8 pan, and Tamsin’s 9 × 13.
How it works
Scale factor = your pan’s area ÷ the recipe’s pan area. A 9-in round is 3.14 × 4.5 × 4.5 ≈ 63.6 sq in, almost exactly an 8-in square (64). Batter depth = batter volume ÷ area, with a cup being 14.44 cubic inches (a US gallon is 231 cubic inches, a cup a sixteenth of that). Deeper batter takes longer to bake through; thinner bakes faster, so check early.
Amounts can be typed as 3, 0.75, 3/4, 1 1/2 or 1½. They’re worked as exact fractions and written as a cook measures them: cups in quarters or thirds, then tablespoons, then teaspoons to the nearest eighth. Everything stays in your browser: no sign-up, nothing stored or sent.