zenith1, thanks.
Debi, agree doesn't need to be perfect, and that's basically what I've done up until my last batch when I doubled my amount. I weighed the bag, divided by the liters of milk it should culture and then calculated how much I need for per 1 US gallon (as that's what I buy my milk in), and then scaled that to the amount of milk in that batch. But, as the manufacturers say will culture up to X amount, and as my culture ages in fridge, I should probably add some extra. That's why I found idiotboy's info interesting in that as a commercial user, even though he probably has fresher culture, he still uses 3.3X the recommended dose. So even at 2X the recommended does, am I using enough? Thus I was curious how much others use per unit of milk, and why, and their results.