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Quick answer

Scale a recipe between any pan shape and size — round, square, rectangular or bundt — by comparing baking areas. Example: a recipe for a 20cm round tin (area ≈314cm²) needs about 1.32× the mixture to fill a 23cm round tin (area ≈415cm²) at the same depth.

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🎂 Cake Pan Size Converter

Scale a recipe from the pan it was written for to the pan you own.

FROM Pan

TO Pan

Quick-reference volume table
PanVolume
6″ round, 2″ deep≈927 ml
8″ round, 2″ deep≈1648 ml
9″ round, 2″ deep≈2085 ml
10″ round, 2″ deep≈2574 ml
8″ square, 2″ deep≈2098 ml
9×13″ rect, 2″ deep≈3835 ml
9″ bundt, 3″ deep≈2780 ml
Bakeware Science

Cake Pan Size Converter

Quick answer

Scale factor = new pan's volume ÷ original pan's volume. Enter your FROM and TO pans (round, square, rectangle or bundt) and depths, and the calculator gives the exact multiplier, plus an overflow warning if you need one.

The cake pan size converter above takes the pan your recipe was written for and the pan you actually want to bake in, round, square, rectangle or bundt, and works out exactly how much to scale the recipe by.

Two pans of the same depth but different shapes rarely hold the same amount of batter. The calculator works out the area of both pans, using π×r² for round tins, side² for square, length×width for rectangles, and an outer-minus-core calculation for bundt pans, then multiplies by depth to get a volume, and finally compares the two volumes to give you a single scale factor.

Switching pans can also change how a recipe bakes, not just how much of it you need. When you're moving to a pan with meaningfully less area, the calculator flags a possible overflow before you pour, and it can help round awkward fractional egg quantities to a whole number too.

Chart of cake pan volume by shape and size: 6 inch round 927ml, 8 inch round 1648ml, 9 inch round 2085ml, 8 inch square 2098ml, 9x13 inch rectangle 3835ml

How much batter different pan shapes and sizes actually hold.

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×1.27
8″→9″ round scale factor
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How It Works

Area, volume and the bundt shortcut

Round pan area is π × radius², square is side², and a rectangle is simply length × width. Bundt pans are the odd one out: they're really a ring, so the calculator works out the outer circle's area and subtracts the area of the central tube. If you don't know your bundt's core diameter offhand, leave it blank and the calculator defaults to a third of the outer diameter, a reasonable estimate for most standard bundt pans.

Once both pans have an area, multiplying by depth gives a volume, and dividing the new pan's volume by the original pan's volume gives the scale factor: how much to multiply every ingredient in the recipe by. A factor above 1 means you need more batter than the recipe makes; below 1 means less, and if the drop is steep enough relative to the new pan's depth, the calculator warns that pouring the unscaled amount in risks overflowing.

Worked example: 8″ round to 9″ round

  • 8″ round area: π × 4² ≈ 50.3 in²
  • 9″ round area: π × 4.5² ≈ 63.6 in²
  • Scale factor: 63.6 ÷ 50.3 ≈ ×1.27

That's a 27% increase, so multiply every ingredient in your 8″ recipe by 1.27 to fill a 9″ pan at the same depth.

Common mistakes

Ignoring the depth when the shape changes

Two pans with the same footprint but different depths hold different volumes, and the calculator’s depth field is doing real work, not just decoration. Measure the actual depth of both pans rather than assuming they match.

Pouring the full original batter into a much smaller pan

If you’re scaling down but pour in the un-scaled amount anyway, it can sit well above two thirds of the new pan’s depth and overflow in the oven. Scale the recipe down by the factor shown, or hold the extra back as a few cupcakes.

Frequently Asked

Questions about
cake pan size conversion

How do I convert an 8 inch cake recipe to a 9 inch pan?
An 8″→9″ round conversion at the same depth needs about 27% more batter, so multiply every ingredient by ×1.27.
Can I bake a 9x13 recipe as two round pans instead?
Yes, enter the 9×13″ pan as FROM and your round pan as TO with quantity set to 2, and the calculator gives the exact scale factor.
Why am I getting an overflow warning?
The calculator warns when you’re switching to a pan with significantly less area at the same depth, since pouring the unscaled batter in would likely overflow. Scale the recipe down by the factor shown, or reserve extra batter for cupcakes.

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