Greetings All!
I have read from a few sources (Kai’s blog most recently) that pitching yeast by weight is the way to go. I can definitely see where this would be advantageous, especially as my batch sizes increase. Is there a quick and dirty way to estimate yeast cell count based on weight? Thick slurry vs thin slurry? Thanks for the help in advance!
I would use Mr. Malty’s pitching rate calculator. http://www.mrmalty.com/calc/calc.html
The third tab has a slurry calculator.
Jamil has some numbers in his Pitching Rate Calculator. I have some numbers too and plan to publish them as a follow-up to the blog post.
For a well flocculating lager yeast I get about 4-5 Billion cells per gram in freshly propagated yeast and 2-3 B/g in yeast harvested form a primary.
The numbers seem to be a bit different for Ale yeasts. I have to check the few data points I have at home.
Kai
I have used Mr Malty for most of my starter calculations over the last few years and also have noticed the slurry tab as well. It has always done me right 
Kai - I mostly do lagers as well and saw the billions per gram calculation in your blog post. I must admit that I do a lot more lagers than ales at this point so that information is top notch. With that in mind to pitch around 500 billion cells I am looking at a thick slurry of around 111-112 grams. Does that sound about right?
Also, what are the differences in weight with ale yeast? More cells? Less cells? If I were going along with the 4.5 billion per gram assumption it would put me at pitching 55-56g for 250 billion cells. Is that a safe assumption?