When I looked in my 2005 Wilton book, it said that a one layer 9x2" round cake calls for 5 1/2 cups of batter. I'm wondering if this is correct? The reason I'm skeptical about this is when looking at the smaller round pans and as they progress in size, the batter amount only increases by 1/2 cup (i.e. 6x2" round = 2 cups batter, 7x2" round = 2 1/2 cups batter, 8x2" round = 3 cups batter). Based on this, I would have thought that the 9x2" round would only need 3 1/2 cups of batter, which would work out nicely for when I do the cake mix extender recipe. It just seems weird that the amount of batter would increase so much.

Well, you can't blame a girl for trying.

But the current Wilton chart for 2" pans also gives the batter requirement for a 9" pan at 5 1/2 cups

http://www.wilton.com/cake/cakeprep/baking/times/party_2inch.cfm

Math has never been my strong point, and I was miserable in Physics..... I rely on the Wilton charts and have been happy with the results.

HTH

I can't help you with box mix based reipes, but most of my scratch recipes create 6-7 cups of batter and that is sufficient for 2 9x2in rounds. A full recipe is needed for the 10x2in pan though. Hope that helps!

As the pan size increases, the amount you would need to add to add one inch in pan diameter increases. One way to visualize this is that if you take a flat disk 6" across and want to make it a flat disk 7" across, you would have to add a 1/2" wide ribbon around the outer edge of the disk. (For those who want the math, the ribbon would be about 6 X pi inches long, or around 19", very roughly.)

If you have an 8" disk and want to make it a 9" disk, you again would just add a 1/2" wide ribbon around the outside of the 8" disk. This time, it would be a significantly longer ribbon needed to go all the way around. (For you math buffs--about 8 X pi, or around 25" long.)

So...since the pan height is the same in all cases, the variation in the amount of batter needed is mostly due to the difference in pan diameter. As noted above, the "ribbon" length increases as the pan size increases. In other words, you only need 1/2 cup to go from a small pan to the next size up, but more than that to go between larger sizes.

I think that they are rounding to the nearest half cup, which causes some confusion. I also think that they may be overestimating a bit on the 9". It may really be something like 5 1/4.

I also suspect that batter may rise better in the smaller pans, because they heat more evenly. (Which is why we may use flower nails, lower oven temps, etc. to deal with bigger pans...)

Class, you can wake up now.

RedPanda

Thanks redpanda!!!

It's great having our own Alton Brown.

(Hope you don't mind the comparison.)

Well here's another question. If I use the cake mix extender recipe (which makes about 7 cups of batter), would I be able to bake it in two 9x2" round pans, or would it not fill out the pans?

My initial response is that it will be short, but I don't know how much.

One way to check is to measure out 7 cups of water and divide it between the two pans. If the water doesn't come at least half way up the pans, it's not enough. (I go more for almost 2/3 of the way when filling pans.)

I can't guarantee the calculations I just did that said that the volume of that size pan is about 9 cups--meaning you'd need at least 4 1/2 cups to fill halfway (and maybe 5 1/2 to have it rise to the desired height, as suggested in the Wilton chart). However, I think that you'd be a little short with the extended batter recipe. I don't know how thin the layers would be, though, since the cake mix boxes claim you can do two 9" layers without the extender. I never bake 9", so I don't know.


RedPanda

P.S. JanH, I don't mind being "compared" to Alton Brown. Food geeks of the world unite!!!

I have split the 5 1/2 cups of batter into two 9" pans many, many times. You'll get a 3" high, 2 layer cake when you're finished. I like this height better than 4", as it gets so hard to cut it decently.

Well, I do know that a cake mix does fill two 8 or 9" pans, but only if they're 1 1/2" tall - not the 2" pans that decorators use.

Here's a handy cake pan conversion chart:
(Also gives volume measurements.)

http://tinyurl.com/2hk777

HTH