I'm basing this on Hamelman's "Bread" conversion information. Basically, to convert from fresh yeast to dry yeast it's 1 oz of fresh yeast equals .4 oz of dry. For instant dry yeast it's 1 oz of fresh yeast equals .33 oz of IDY.

So if you are using IDY you can divide by 3. So 2g / 3 = .66666g. See if that works for you, I think that's the correct math.

Dave