Cake Pan Size Converter

Convert cake, brownie, and tart recipes between round, square, and rectangular pans while keeping batter depth and crumb texture consistent.

Original Pan (Recipe Default)

in

Target Pan (Your Pan)

in
Recipe Scaling Factor
×1.27

Multiply every recipe ingredient by 1.27

Pan Geometry Comparison

Original Pan Area: 50.3 sq in
Target Pan Area: 63.6 sq in
Volume Differential: +26.5%
Oven & Baking Adjustment

Because the target pan is larger, reduce baking time slightly and lower oven temperature by 25°F (15°C) if baking unscaled batter.

Common Cake Pan Size Equivalencies

Use this quick reference to swap pans without recalculating whole recipes:

Pan Size & Shape Surface Area (Approx.) Equivalent Swaps
8" Round (2" deep) 50.3 sq in (≈ 100 cu in) 7" Square pan (49 sq in) or 8.5 × 4.5" Loaf pan
9" Round (2" deep) 63.6 sq in (≈ 127 cu in) 8" Square pan (64 sq in) or 9 × 5" Loaf pan
10" Round (2" deep) 78.5 sq in (≈ 157 cu in) 9" Square pan (81 sq in) or 11 × 7" Rectangular pan
9 × 13" Sheet / Brownie Pan 117.0 sq in (≈ 234 cu in) Two 8" round pans (100.6 sq in) or two 9" rounds with thin layers

How Surface Area Controls Heat Transfer and Crumb Rise

Baking a cake is a delicate thermal dance between starch gelatinization, egg protein coagulation, and steam expansion from chemical leaveners (baking powder and baking soda). When you alter pan geometry, you dramatically change how heat moves into the batter.

Consider our benchmark example: converting an 8-inch round cake recipe to a 9-inch round pan:

Pan Geometry & Scaling Factor:
• Original (8" Round Area) = π × (8 / 2)² = 16π ≈ 50.27 sq inches
• Target (9" Round Area) = π × (9 / 2)² = 20.25π ≈ 63.62 sq inches
• Scaling Factor = 63.62 / 50.27 ≈ 1.2656 ≈ 1.27×

To preserve the exact layer thickness, height, and baking duration of the original 8-inch recipe, you must multiply every ingredient by 1.27×.

What Happens If You Don't Scale the Batter?

If you pour an unscaled 8-inch cake batter into a 9-inch pan, the batter will spread thinner. This increases the surface-area-to-volume ratio, allowing water to evaporate and the core to cook much faster.

  • Shorten Baking Time: Begin checking for doneness (with a toothpick or cake tester) 5 to 8 minutes earlier than stated in the recipe.
  • Prevent Dry Edges: Because thinner batter bakes quickly, reduce the oven temperature by 25°F (15°C) to prevent the outer crust from drying out before the center rises.
  • Never Overfill: Regardless of pan size, never fill cake pans more than two-thirds (2/3) full to ensure proper airflow and avoid batter spilling onto your oven floor.
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Frequently Asked Questions

How do I convert 8 inch to 9 inch?

An 8-inch round pan has an area of 50.3 square inches, while a 9-inch round pan has an area of 63.6 square inches. Converting from an 8-inch pan to a 9-inch pan requires multiplying all ingredients by 1.27× (a 27% increase in batter). If you bake the original unscaled 8-inch recipe in a 9-inch pan, your layers will be thinner; reduce your oven bake time by 5 to 8 minutes.

What is an 8 inch round pan equal to?

An 8-inch round cake pan (50.3 sq in) is virtually identical in surface area to a 7-inch square pan (49.0 sq in) and a standard 8.5 × 4.5 inch loaf pan (38.3 sq in to 45 sq in depending on depth). An 8-inch square pan, by contrast, has 64 square inches—making it 27% larger than an 8-inch round pan and almost identical to a 9-inch round pan.

Can I double a cake recipe?

Yes, you can double a cake recipe (2.0×), provided your stand mixer bowl has sufficient capacity to incorporate air into butter and eggs without overflowing. When doubling a cake formula originally designed for one 8-inch pan, you can simply divide the doubled batter evenly across two 8-inch pans or bake in a standard 9 × 13 inch rectangular baking pan (which has an area of 117 sq in, roughly 2.3× an 8-inch round).