I was able to accurately calculate out a cider recipe for BeerSmith. It was for frozen apple juice concentrate. It's kind of stupid for the way you have to do it to get it to work.
The apple juice concentrate that I used, when properly mixed with water, has a gravity of 1.045. I figured out the gravity by multiplying the grams of sugar per serving/container. Then how many containers per gal. It works out to 448 grams per gallon, just under 1 Lb.