Enter the pan your recipe calls for and the pan you have — get an exact time adjustment in seconds.
Open full calculator →When you swap to a different pan size, the batter depth changes — and batter depth is what actually determines how long something takes to bake. A larger pan spreads the batter thinner, which means it cooks faster and can dry out at the edges before the centre sets. A smaller pan concentrates the batter deeper, which means the outside is done long before the middle catches up. The difference matters more for dense items like brownies and quick breads than for lighter batters like chiffon cakes.
The right way to adjust baking time isn't a simple percentage — it's based on the ratio of the two pan areas raised to the power of 0.7, which is the formula the baking industry uses to account for how heat penetrates a thicker layer of batter more slowly than a thin one. PanSwap does that calculation automatically so you don't have to.
Pan shape also matters more than most recipes acknowledge. A 9-inch round pan and an 8×8 square pan are nearly identical in area (63.6 vs 64 sq in), so they're essentially interchangeable. But a 9-inch round and a 9×9 square are not — the square has 81 sq in against the round's 63.6, a 27% difference that will noticeably affect your bake.
The guides below cover the most common pan swaps in detail, with size comparison tables and specific notes for different bake types.
Every guide includes a size comparison table, time adjustments, and answers to the questions real bakers actually ask.
The 8×8 is 79% the area of a 9×9. That difference matters for brownies and cakes but less so for bars. Here's exactly what to change.
Read guide → Pan substitutionTwo 8×8 pans are actually 9% more area than one 9×13. Great for potlucks — but there are a few things to know before you split the batter.
Read guide → Reference chartEvery common pan size in one place: area in square inches, volume in cups, closest substitutes, and best uses. Bookmark this one.
View chart → Shape conversionA 9" round and an 8×8 square are nearly identical in area (63.6 vs 64 sq in). See the full conversion table for every diameter.
Read guide →Most blogs give you a rule of thumb. PanSwap gives you the math.
Both pans drawn side by side at the same scale so you can immediately see how different the size really is.
Uses the baking industry standard: adjusted time = original × scale factor^0.7 — not a rough percentage.
Brownies, layer cakes, quick breads, and cheesecakes each respond differently to pan changes. PanSwap adjusts the notes accordingly.
Every swap gets a confidence score — Safe, Works with adjustments, or Significant changes needed — so you know what you're getting into.
Mix and match rectangular, square, and round pans freely. The calculator handles the area math regardless of shape combination.
For large size differences, the calculator flags when to lower the oven temperature and explains why.
Yes, but with adjustments. An 8×8 pan is 64 sq in; a 9×9 is 81 sq in — the 8×8 is 79% the area. Your batter will sit deeper, so increase baking time by roughly 10–15%. The swap works well for brownies and bars; layer cakes need more care.
The industry formula is: adjusted time = original time × (new area / original area)^0.7. If the new pan is larger, the batter is shallower and cooks faster; if smaller, it's deeper and takes longer. Always check for doneness with a toothpick — pan material and oven variation matter too.
Yes. A 9-inch round (63.6 sq in) is nearly identical to an 8×8 square (64 sq in) and the two are interchangeable. A 10-inch round (78.5 sq in) is close to a 9×9 (81 sq in). Find the nearest area match and adjust time accordingly.
Too large: batter spreads thin, cooks faster, and can dry out at the edges. Too small: batter sits deep, takes longer to cook through, and can overflow. Swaps within about 25% area difference are manageable; beyond that, expect significant texture changes.
Usually no — only time changes. The exception is switching to a much smaller, deeper pan: in that case, lowering the temperature by 25°F and extending time can help the inside cook before the outside over-browns.
Yes — two 8×8 pans (128 sq in combined) give you about 9% more area than a 9×13 (117 sq in). Batter will be slightly shallower, so reduce baking time by 5–8 minutes. Great for doubling a recipe or baking for a crowd.