Sorry I didn't back to you faster Kaylinda - it was Easter weekend plus I needed a little time to do a bit more research. One interesting fact that I did glean from Sarah Phillips at Baking911
is that all packaged cake mixes are high-ratio - so the flour to sugar weight ratios are going to be about equal. Taking that information and digging back through The Baker's Manual
again ... and remembering some things Shirley Corriher had said in CookWise
about the differences in baking (measurements and ingredients) between home cooks and professionals ... I began to piece together a plan.
Assumption #1: If the recipe calls for a white cake mix as the foundation of the recipe but doesn't specify a brand AND the ingredients are not given in weights ... then probably the flour, sugar, leavening and salt are the only significate ingredients - and the other ingredients in the mix have plenty of wiggle room.
Assumption #2: The weight of sugar and flour will be about equal, and the amount of leavener and salt will be proportional to the amounts found in a "scratch" cake.
Assumption #3: Converting from lb/oz weights to common teaspoon/cup volume type measurements will get us close to the same results.
: to approximate
a 18.25 oz White Cake Mix by weight (minus everything but flour, suar, baking powder and salt)
8.875 oz Bleached Cake Flour
8.875 oz Sugar
0.334 oz Double Acting Baking Powder
0.127 oz Salt
Fact: In baking, the type of flour you use and how you measure it affacts the outcome. Good cookbooks, that include baking recipes with volume measurements, will tell you what flour they used and how they measure the flour in their recipes. There are basically 4 ways to measure flour by volume - and the differences in weight (based on cake flour) per cup:
1 - SIFTED
: You sift the flour directly into the measuring cup - about 3.5 oz
2 - SIFT & SCOOP
: Sift the flour once into a bowl and then scoop it out with the measuring cup - about 3.7-3.8 oz
3 - SPOON & SPRINKLE
: You use a spoon to dip the flour out of the bag and sprinkle it into the measuring cup - about 4 oz.
4 - DIP & SCRAPE
: You dip the measuring cup into the bag of flour and scrape it off against the side/top flap of the bag to level it - about 4.6 oz.
NOTE: In 1-3 above, the measuring cup is never tapped or shaken to level the flour - fill to overflowing and use a straight-edge to scrape off the excess.
: using the Spoon & Spinkle method from above for flour and sugar
2 1/4 Cups Bleached Cake Flour
1 1/4 - 1 1/3 Cups Granulated Sugar
2 Teaspoons Double Acting Baking Powder
1 Teaspoon Granulated (table) Salt
This is about as close as I can "guesstimate
" - hope it gives you a starting point that will work for you.