Brownie Pan Conversion Calculator
8" sq vs. 9" sq vs. 9×13: scaling factor + bake-time delta. Same depth assumed.
Result
General calculation reads
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How to use this calculator
- Pick original pan from recipe.
- Pick the pan you have.
- Multiply recipe ingredients by the ratio.
- Adjust bake time and check early with toothpick.
About this calculator
Brownies are area-driven: a 9×13 pan has 1.83× the area of an 8" square, so the recipe needs to be multiplied by 1.83 — or the pan-half-filled. If you keep the original recipe in a bigger pan, batter thickness drops, sides over-bake, and edges turn to leather. The bake-time scaling is approximate: a thinner sheet bakes faster (less thermal mass to heat through), but only slightly. Always check with a toothpick at 70% of estimated time.
Frequently asked
Why double a recipe in a 9×13?+
Bake time can go up?+
Edge vs. center brownies?+
Does the metal/glass matter?+
Why not a depth-based formula?+
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