How to work out calories from amended recipes

kegan5

I'm trying out the diet soda Cupcake recipes and wondered how I can work out the calories?

For anyone wondering what I'm talking about, I read on various skinny cake sites that you can make low calorie cupcakes by replacing the egg and water etc in cake mix's with a diet soda (Sprite Zero in this case).

The packaging on the cake mix says Servings = 12. 170 Calories per 1/12.

I assume this 170 calories is when the cake is made using the eggs as recommended by the packaging... So would the actual calories be different using the soda?