Harvesting & Propogating from Bottle - how much do I have?

So I have stepped up the dregs in 1 liter, and after a cold crash a nice layer of yeast is evident. Given that most (?) recipes designate yeast quantity as # of smack packs, is there a way to estimate the smack pack equivalency?

Will a 1 liter step-up, for example, yield X number of cells per milliliter predictably and reliably? If so, what is the yield and how can one convert this to a "smack pack" equivalent?

Mr Malty has your first answer:
http://www.mrmalty.com/calc/calc.html

I've only used a smack pack once so I can't help you there.