Hey there,

In a few weeks time I'm making my first square cake! it will be a 15x15 square.

But I have no idea how much cake mix to use!

I bake everything from scratch, so no box mixes. And I'm from the UK so the whole Cups measurement means nothing to me haha.

I usually go by number of eggs, 2 for 2x4 inch rounds, 3 for 2x6 inch rounds, 4 for 2x8 inch rounds, etc.

If anyone could help me out, that would be magic!

Thanks :)

1 layer, 2' high is about 20 cups batter, depending on your recipe. 

20 cups=4.73 liters

Just for your future knowledge what you really are asking is how much 'batter' do I need :)