A quick reference for common pans
View the pan substitution matrix or download its one-page PDF. For your exact dimensions, use the calculator above.
Choose the right comparison
Same batter depth compares total base area. Use it when you want the batter to sit at approximately the same depth in both sets of pans. Different batter depth compares base area multiplied by the planned batter depth. Enter the actual depth of batter you intend to pour, not the height of the pan walls.
The shape model assumes straight vertical sides and a level base. Measure the internal diameter, width or length. Rounded corners, sloped loaf tins, fluted pans, tube pans and Bundt pans do not match these simple shapes. This calculator does not estimate an arbitrary fill percentage or account for a centre tube.
The pan conversion formula
Round base area = π × (internal diameter ÷ 2)² Square / rectangle base area = internal width × internal length Total base area = one pan’s area × number of pans Same-depth multiplier = target total area ÷ original total area Depth multiplier = target area × target depth ÷ (original area × original depth)
Units are converted to centimetres internally before comparing the pans. One inch is exactly 2.54 cm, and 10 mm is 1 cm. A cubic centimetre is one millilitre, so the depth mode also reports the planned batter volumes in ml.
Worked example: an 8-inch round to a 9-inch round
The two circular areas share the same π factor, so it cancels. The recipe multiplier is 9² ÷ 8² = 81 ÷ 64 = 1.265625. That is 26.5625% more batter at the same depth. A recipe containing 200 g flour becomes 253.125 g flour before practical rounding. Converting the other way gives 64 ÷ 81 ≈ 0.7901, or about 20.99% less batter.
Worked example: one 9 × 13-inch pan to two 8-inch rounds
The original area is 9 × 13 = 117 in². The two rounds have a combined area of 2 × π × 4² = 32π in². Their ratio is 32π ÷ 117 ≈ 0.8592. Begin with about 86% of the recipe if the intended batter depth is comparable. Pan count is part of the calculation; two pans are not treated as one.
Use the factor on your recipe
The button above opens the whole-recipe scaler with the factor filled in. Paste the ingredient list, then review ambiguous quantities and notes before copying or printing. Ingredients are kept in their original units; this does not turn a cup measure into grams.
What this says about baking
Area and planned volume describe how much batter to prepare, not how heat moves through it. Pan material, shape, actual batter depth and the recipe can change the bake. Check the original method and judge doneness appropriately; this tool supplies no universal time, oven-temperature change or leavening correction.
For practical background, see King Arthur Baking’s alternative pan sizes. Its area-based substitutions depend on a suitable depth and recipe. The geometric calculations and examples here are computed independently.
Frequently asked questions
- Can I compare metric and inch pans?
- Yes. Each set of pans has its own unit, so a 20 cm pan can be compared directly with an inch-sized pan.
- Can I use different numbers of pans?
- Yes, enter a positive whole number for each set. The comparison uses the combined areas or planned volumes.
- Can I use wall height as batter depth?
- No. Wall height includes headroom. Depth mode needs the intended batter depth, which you must determine from the recipe and your pan.