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I want to make a cake for my sister's birthday. The recipe I have is for making wedding cakes and makes a 3 layer 9" cake. I want to make a 2 layer 8". I figure it will work by cutting the recipe in half.

Questions:

I've never done this with a cake and wonder if it will effect the outcome. Flavor, teture?

If I make the full recipe, will it hurt to bake two 8" layers and hold the balance until they are baked and cooled?

Is there a formula for cutting a cake recipe in half?

fitzie

It kind of depends on what kind of cake it is. I don't sweat it too much and just go with what seems logical. I switch pan sizes all the time.

Amy

If you make the full recipe and just bake what you want as layers, you can either bake the rest as cupcakes or make another layer and freeze it, or hold the batter for a day or so and then bake it.
Scaling recipes is done by figuring out what percent of the original you need. To double a you need 200%. To halve one you need 50%. You need to figure out how much batter your first recipe makes, and how much you need for 2 8"layers. There are charts of that info out on the interwebs. Then you multiply the amount of the original by the percentage you need to get the new amount.
Say you need 75% of the original. You multiply every measurement by .75.

One 9" layer uses about 6 cups of batter and one 8" layer uses about 4.5 cups. So 3 9" layers will need 18 cups and 2 8" layers will need 9 cups, so making 1/2 recipe should work out perfectly.
They may need a bit more time to bake as they are thicker per layer than the 9" ones.

Thanks. I'm going to try a half recipe and see how it works.
fitzie

Your estimate of half a batch for 2 - 8 inch layers is just about right.

Remember: pi * r *r = area of the pan. ( I don't know how to type pi R squared here).
Multiply by the number of layers.

Result: 2 - 8 inch layers is real close to half of 3 - 9 inch layers.

You can always fall back on your high school geometry to figure the quantity conversions for different pan sizes.


Yeah - I'm a math geek.

Fitzie, To reconfirm, you have a recipe for 3 - 9-inch pans, and you want to scale it to 2 - 8-inch pans.
First PRESUMPTION is that the pans are the same depth, a standard 1-1/2 inch. If this info is correct, then it's just a basic calc.
If the pans are different depths, then some more adjustments are needed,

A cake pan is geometrically in the form of a (short) cylinder, so --

Find the volume of the 9" pan cylinder; [(9^2 x pi)/4] x 1.5 = 95.43 cubic inches
Find the volume of the 8" pan cylinder; [(8^2 x pi)/4] x 1.5 = 75.4 cubic inches
(I'm using D-squared times pi, divided by 4), it's the same as (pi times R squared)

Now we'll find the ratio of (3) 9-inch pans, to (2) 8-inch pans
95.34 x 3 = 286.29 cubic inches (Total volume of known recipe)
75.4 x 2 = 150.8 cubic inches (volume of reduced recipe)

Ratio = 150.8(X) / 286.29, solve for X

X = 52.7% ---> THIS is your recipe factor.

So cutting the recipe in half will probably get you there, except you'll be about 3% short of full 8" pans.
Then again this is baking, and the amount of levening or adjustments thereof can easily make up for this.

Hope this helps!

I used to design rocket engines, but now that the space shuttle is gone, I sit at home and pet the dogs.

Thanks everyone for your explanations. I should have listened to my father. He always said you never know when this information will come in handy!
fitzie