Cake Pan Size Converter

Swapping pans? Scale your batter perfectly by matching the pan areas — no guesswork, no overflow.

📖 How it works & FAQ

Original pan (the one the recipe is written for)

New pan (the one you want to bake in)

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batter multiplier (new ÷ original)

Why pan size changes your recipe

A cake recipe is really a recipe for a volume of batter, and that volume is set by the pan it was written for. Swap in a pan with a different footprint and the same batter will either overflow the sides or bake into a thin, dry disc. The fix is simple math: cakes bake to roughly the same depth, so what matters is the surface area of the pan bottom. Match the areas and the batter depth — and therefore the bake time and texture — stays about the same.

The area-ratio method

This tool computes the area of each pan and multiplies your batter by new area ÷ original area. Round pans use π × r² (radius is half the diameter). Square and rectangular pans use width × length. So a 9-inch round (about 63.6 in²) swapped for an 8-inch round (about 50.3 in²) gives a multiplier of 0.79 — you'd make about 79% of the original recipe. Multiply every ingredient, including eggs, by that same factor.

How to use it

Pick the shape of the original pan your recipe was written for and type its measurements in inches.
Pick the shape and size of the new pan you actually want to bake in.
Read the batter multiplier at the bottom — it updates instantly as you type.
Multiply every ingredient in your recipe by that number, then adjust bake time (bigger, shallower pans finish faster; deeper ones take longer).

FAQ

Do I measure the pan across the top or bottom?: Measure the flat inside bottom. Many pans flare outward, so a top measurement overstates the true baking area.
Should I change the oven temperature?: Keep the temperature the same. Only the bake time shifts — start checking a larger, thinner cake several minutes early.
Can I convert between round and square pans?: Yes. The tool only cares about area, so mixing shapes works fine — a common rule of thumb is that a square pan holds a bit more than a round pan of the same dimension.
How full should I fill the new pan?: Aim for about two-thirds full to leave room for rise. Results here are estimates — watch your cake and use a toothpick to confirm doneness.