I read that 10DCU=1U, I'm not sure where, I think Caldwell's. Personally I just write down how the package describes it should be used and the net weight, and do the math. For example my Flora Danica package content is 12.7g, 50U and says 1 U will work for 6G. So 12.7/(50*6)=0.04grams per Gallon of milk. You can google pdf spec documents from CHR, Choozit, and other producers describing their products and recommended dosages for different popular cheeses, as they are not always the same.