Quote Originally Posted by Suki Wingy
My last question (for now) is, Does anyone happen to know of a site where you can enter the numer of pounds per bag and how many cups used per day, and it would give you the number of days the bag would last? That would be really handy.
Density = mass/volume
Pounds are a measure of mass.
Cups are a measure of volume.
The lbs/cup then depends on the density of a particular kibble.
You can get a ballpark estimate of "kibble density" by weighing a known number of cups of your current kibble. I'm not sure how much kibble density varies (never really considered it), but this method will at least give you some method for estimation.

I don't really have time to get involved with the food discussion right now, but I thought I'd just chime in with this to help you out. Math is your friend.