Originally Posted by enid
According to Wyeast calculator a .5L starter stepped up to a 2L starter on stir plate will give you 453 billion or 1L to 1L gives you 397 billion.
I find that calculator very much inferior to the mrmalty version. Mainly because it does not adjust the initial yeast pack for viability. Secondly, it does not relate the starter to YOUR batch of beer.
But it does seam to have a good method for calculating the effects of two steps.
I calculate I need a final pitch rate of 20.6 million cells per ml for my 1.056 batch of lager. According to the wyeast calculator if I do a .5 gallon starter on a stirplate and pitch that into a .5 gallon starter also on a stirplate I get a final pitch rate of 28 million cells per ml. So I'll be over pitching by 26%. Maybe a bit less if you factor in the reduced viability of the initial vial of yeast.
So is over pitching by 26%+/- a big deal? Should I cut back on my second starter step? WWJD?