Scale up problem :S Please help! :)

The fist thing you need to do is find out Exactly how much bigger your 10" pan is than your small one. So pour water into your small pan so that the water  comes up to the level that you would be using for your UN-baked batter. Measure that water into a very large measuring cup or something that is calibrated, like a container that has notations for 600 ml. 750 ml. 1000 ml. etc. Next take your large pan and pour water up to the mark that you woulds expect to see if it was a batter. (like maybe half way up the side of the lg pan. Now, measure that water. Got it? So, what is the difference between the small and large pans. EXAMPLE ONLY: small pan might be 4 cups of liquid while the big pan might measure 6 cups. So, from there it's simple.  Bigger pan is 50% more than the small pan. If that's the case then multiply your cake recipe by 1.5  Thus 2 eggs now become 3 eggs. Do that with evey ingredient. As for baking, keep the same temp as before but just bake a bit longer. Then test with a tooth-pick. Good luck

Mathematically, a 10" pan is 1.78 times as large as a 7 1/2" pan of the same depth, 2.04 times as large as a 7" pan, and 1.56 times as large as an 8" pan.

Remember, the formula for the volume of a cylinder is PI*r²h where PI=3.14159, r=radius (one half the diameter), and h=depth. If the depth is the same, the volume is proportional to the radius squared as PI and h cancel out.

10" diameter = 5" radius, r²= 5x5=25

8" diameter = 4" radius, r²=4X4=16

7" diameter = 3.5" radius, r²= 3.5x3.5= 12.25

7.5" diameter = 3.75" radius, r²= 3.75x3.75 = 14.06

Then again RicWhiting's method is faster and less mind twisting
 

Before going ahead making a larger cake with a small cake recipe, you should read up on the effects of increased diameter on the final cake.  There are structural problems similar to making domes - domes are heavy, bigger domes are heavier.  So you can't just increase the same batter proportionately for a larger cake. 

Rose Beranbaum's Cake Bible gives some explanation for this and what to do about it - which amounts to reducing by a small amount the quantity of baking powder if the cake jumps two sizes. A recipe for a 7 - 8 inch cake will not work for a 9 - 10 inch cake etc.In her recipes for wedding cakes, for instance, there are two different recipes for the smaller top tiers and the larger bottom tier. 

I take it you're in the UK, since you speak of caster sugar and marks for oven temp. 

You might find it harder to find flour that is not self-rising, but it would be worth it.  It seems that self-rising flour is slightly over-leavened as it is, and may cause your final cake to collapse.  (If it lifts too high over a larger area, it will not have the structure to hold itself up. 

If you want, i can copy her recipe for butter cake and the different quantities of baking powder you need for the different diameters.  Her method builds more structure than the standard creaming method, if that's what you're using, and the cake comes out wonderfully moist and perfect. 

Quote:

Originally Posted by TeaCritter 

Hey everyone, thanks for some great tips opn how to work this out, I'll be honest and admit to some really making my head swim haha my mathamatics is ok but for some reason my mind just goes blank.

 

I'll give them a go though, any better recipies that you feel more appropriate for a 10 inch round I'd be happy to hear.

 

Oh and Siduri...Yes I'm from the uk and it's really quite easy to get plain flour over here, I don't know where you heard you can only get self rasing?

Hi TeaCritter.

My daughter lives in London and she had some trouble finding plain flour (but perhaps the problem was she didn;t know how it was called.  She studied in the US where it was called "all purpose" and in italy where it's called 00. 

I went to see the cake bible recipes, and i have to admit defeat - maybe someone with better math skills than me (which would mean ANY math skills at all) could figure out the dosages for a ten inch pan.  Sorry, i was sure one of them was for two ten-inch layers, and instead it was for two twelve-inch layers,

Sounds good, teacritter.  Let us know, and send the recipe if it's not a secret.