How many boxed cake mixes does it take for a 10x3 inch round pan?
You probably need about 9 cups of batter. I use 6 cups for a 10 inch round, 2 inch high pan. 9 cups would be roughly 2 cake mixes. Most mixes are between 4-6 cups batter.
i use the cake extender mix and it makes up a 10" just near perfect (uses one box plus the extra ingredients-very tasty too) look up the recipe and it will tell you exactly