Pan Size Converter
Convert between round, square and rectangular pans by volume, and adjust the baking time. A 9-inch round and an 8-inch square are not the same pan.
Enter the recipe time to get an adjusted time for the new pan.
Pan comparison
127 → 128 cu in — volume ratio ×1.01 · 8.9 cups vs 8.8 cups
Good swap — the volumes are close enough.
Adjusted baking time: about 35 minutes (was 35 minutes). Start checking 5–10 minutes early.
1 US cup = 14.44 cubic inches. Pans convert by volume, not by diameter — a 9-inch round holds about 25% more than an 8-inch round.
Formula used: Round pan volume = π × r² × depth. Square / rectangular volume = length × width × depth. Time scales roughly with the square root of the volume ratio.
How the pan size converter works
Pans convert by volume, not by diameter. The volume of a round pan is π × r² × depth, so a 9-inch round holds about 8 cups and an 8-inch round holds about 6 — a one-inch difference is a 25% difference in batter. The tool compares round, square and rectangular pans by volume and tells you whether the swap works, or whether the batter will overflow or bake too thin.
Watch out for
If the new pan is more than about 25% smaller, the batter will overflow; if it is much larger, the cake will be thin and dry. When the volume changes, the baking time changes too — a deeper batter bakes longer. Check for doneness 5–10 minutes before the recipe time when you change pans, and use the baking time adjuster for a starting estimate.
Try next: Oven Temperature Converter · Recipe Scaler · Baking Time Adjuster
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