Most recipes that call for Bisquick have volume measurements, but I've read it's better to measure most dry ingredients by mass (not to mention more convenient and less messy). So what is the proper conversion factor for Bisquick (i.e. it's density)?  I assume it's close to that of flour, but different types of flours have different densities and I wasn't sure which one to use or which one the Bisquick manufacturers assume when developing their recipes. 
The General Mills site has the image of the "original" pancake mix along with it's nutrition facts.  The serving size is 1/3 cup mix (40 g)  This means that one cup of the mix should weigh 120 g (4-1/4 oz).   