Cake Pan Conversion Calculator
Scale batter between different cake pan sizes.
Optional, to scale batter
Results update as you type.
How it works
Swapping a recipe into a different-sized cake pan requires scaling the batter, and this calculator handles the math for round pans. You enter the original pan diameter, the new pan diameter, and optionally the original batter amount, and it returns the area scale factor and the adjusted batter needed. The key insight is that batter fills a pan by area, and a circle's area grows with the square of its diameter, so going from an 8-inch to a 10-inch pan is not a 25 percent increase but about 56 percent, because the area ratio is 10 squared over 8 squared. Multiplying your original recipe's batter by this factor tells you how much to make for the new pan to keep the same cake depth. If you scale up, remember to also scale ingredients proportionally, and expect a slightly different baking time — larger, wider cakes often bake a bit faster per inch of depth, while deeper ones take longer, so check for doneness rather than relying on the original time. Filling pans about two-thirds full is a good rule to avoid overflow. This calculator uses round pans; for square or rectangular pans, compare actual areas (length times width) instead. Enter the two diameters to find the scale factor and adjusted batter.
Scale factor = (new diameter)² ÷ (old diameter)²
The amount of batter a round pan holds is proportional to its area, which grows with the square of the diameter. Dividing the square of the new diameter by the square of the old diameter gives the scale factor. Multiplying the original batter amount by that factor gives the amount for the new pan.
Source:Geometry (area scaling)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter original pan diameter and new pan diameter.
- 2
Adjust the options
Adjust original batter amount if they apply — sensible defaults are already set.
- 3
Read your result
Area scale factor updates instantly as you type — no button to press.
Frequently asked questions
How do you convert a recipe to a different pan size?
Scale the batter by the ratio of the pans' areas. For round pans, that is the square of the new diameter divided by the square of the old diameter. Multiply your original batter and ingredients by this factor. Going from an 8-inch to a 10-inch pan needs about 1.56 times the batter, not just a little more.
Why square the diameters?
Because a cake pan holds batter by area, and the area of a circle is proportional to the square of its diameter. So doubling the diameter quadruples the area and the batter needed. Simply comparing diameters directly would badly underestimate how much larger a wider pan is, which is why you square them.
Does baking time change with pan size?
Yes. A wider, shallower cake generally bakes faster because heat reaches the center sooner, while a deeper cake takes longer. When you change pan size, use the original temperature but start checking for doneness earlier or later than the original time, testing with a toothpick, rather than assuming the same baking time applies.
How full should I fill a cake pan?
Fill cake pans about one-half to two-thirds full to leave room for rising without overflowing. If the scaled batter would overfill the new pan, bake the excess as cupcakes or in a second pan. Overfilling causes spills and uneven baking, so it is better to have a little extra batter than to pack the pan too full.
What about square or rectangular pans?
For non-round pans, compare actual areas: length times width for a rectangle, or side squared for a square. Divide the new pan's area by the original's to get the scale factor, then apply it the same way. This calculator uses round-pan diameters, but the underlying area-ratio principle works for any pan shapes you can measure.