I'm going to make a 19 inch sheet cake using indydebi's buttercream icing however, how many Duncan Hine's cake mixes should I use? It says 14 cups but how many cups does one Duncan Hine's cake mix make? Any help ? THanks!

you will get about 5 cups from one Duncan Hines cake mix, but if you use the doctored duncan hines you will get 15 1/2 cups. That would mean you need to do two batches of the doctored cake mix for a two layer 19 inch.

What is the doctored Duncan Hines cake mix?

This cake recipe is the maximum quantity for your 5 quart mixing bowl. It mixed up perfect in my Kitchen Aid Accolade. It yielded 15 1/2 cups cake batter.

2 Duncan Hines Butter Recipe cake mixes (I guess you could use any flavor)
2 cups All Purpose Flour
1 1/2 Cups Sugar
4 Sticks Butter (I used half butter, half margarine)
2 2/3 cups water
6 eggs
1 box French Vanilla Pudding Mix (instant)
2 tsp Baking Powder

Cream butter and sugar together. Add eggs, mix until blended. Add cake mix, pudding, flour and baking powder. Blend on low while drizzling in water in a thin stream. Mix until smooth (doesn't take long), and bake according to directions for your pan size. I had to share this because it turned our so good. I hope someone else enjoys!!

OK, I am going to answer all three at once, The recipe makes 15 1/2 cups of batter total. For this particular cake, I had to make this recipe four times, as the 16"square calls for 151/2 cups batter alone. When I say crumb, I mean that the texture of the cake has a fine crumb, which is just to describe that it is moist and has a great texture. It doesn't crumb any more than any other cake.
I have never mixed 3 cake mixes at a time, but if I had a bowl big enough, I would probably try!! The recipe listed gives you the capacity of 3 cake mixes when you consider that a cake mix produces somewhere around 5 cups to 6 cups batter