Cake Pan Converter
Find the exact scale factor to adjust any cake recipe when switching pan sizes.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Select the pan your recipe specifies and the pan you actually have. The calculator finds the scale factor to multiply every ingredient by. Here is how to use it:
- Choose the original pan. Select the shape and size your recipe calls for. Common sizes include 8" round, 9" round, 9x13" rectangle, and 8" or 9" square.
- Choose your pan. Select the shape and size of the pan you have available. The calculator supports round, square, and rectangular pans in standard sizes.
- Apply the scale factor. Multiply every ingredient in your recipe by the scale factor shown. A factor of 1.27 means you need 27% more of everything. A factor of 0.79 means you need 21% less.
- Adjust baking time. Baking time is not purely linear. As a general rule, a shallower, wider pan bakes faster (reduce time by 5-10%), and a deeper, narrower pan bakes slower (increase time by 5-15%). Start checking for doneness earlier than usual and use a toothpick or cake tester.
The scale factor is based on the ratio of pan areas. A recipe designed for an 8" round pan scaled to a 9" round pan needs about 27% more batter because the 9" pan has 27% more surface area.
About Cake Pan Size Conversions
Every cake recipe is designed around a specific pan volume. When you change the pan, you change how the batter spreads and how deep it sits, which affects both the quantity of batter needed and the baking time. The most reliable way to scale is by pan area (or volume for deep pans), not by diameter alone.
Round pan area: pi times radius squared. Square pan area: side squared. Rectangle area: length times width. Comparing these areas gives you a precise scale factor. For example, the 9" round (63.6 sq in) is 27% larger than the 8" round (50.3 sq in). If your original recipe used an 8" round and you are baking in a 9" round, multiply every ingredient by 1.27. All calculations run entirely in your browser. No data is stored or transmitted.
Frequently Asked Questions
Can I substitute a 9x13 pan for two 9" round pans?
Yes, a 9x13 inch rectangle pan (117 sq in) has almost the same area as two 9" round pans (two times 63.6 sq in = 127 sq in), so the batter quantity is nearly identical with no scaling needed. The 9x13 will be slightly shallower and bake a bit faster since the batter is more spread out. Expect to reduce baking time by about 5-10 minutes. This is one of the most common and reliable pan substitutions in baking.
How do I adjust baking time when changing pan sizes?
Baking time depends on the depth of the batter, not just the quantity. A wider, shallower pan bakes faster because heat reaches the center more quickly. A narrower, deeper pan bakes slower. As a rough guide, if your pan is significantly larger (batter is shallower), reduce time by 10-15% and start checking early. If your pan is smaller (batter is deeper), add 10-20% and check doneness with a toothpick. Internal temperature of 200-210°F is a reliable test for cakes.
Does the scale factor apply to leavening agents like baking powder?
For most pan-size adjustments, yes, scale leavening agents proportionally with everything else. However, if you are significantly scaling up (more than doubling or tripling a recipe), leavening does not always scale linearly. Very large batches often need slightly less leavening as a percentage of flour than small batches. A good rule of thumb: when scaling up by more than 3x, use about 80-85% of the calculated leavening amount and taste/test accordingly.
What is the area of common cake pan sizes?
Here are the areas of the most common cake pan sizes: 6" round = 28.3 sq in, 8" round = 50.3 sq in, 9" round = 63.6 sq in, 10" round = 78.5 sq in, 12" round = 113.1 sq in, 8" square = 64 sq in, 9" square = 81 sq in, 9x13" rectangle = 117 sq in, 11x15" rectangle = 165 sq in. Use these to calculate scale factors manually or let this calculator do it for you.