Trouble calculating pitch rate with dry yeast

[freshhoarse]

We are gearing up to brew our first batches and I plan on using dry yeast as a house strain.
Running calculations on dry yeast pitch rates is very frustrating, as no one seems to know what true cell counts are for dry yeast. It seems to run anywhere from 6 bil cells/g to 20 bil cells/g depending on where you look. The 6 billion cells is the guaranteed cell count from Fermentis, while 20 billion comes from Jamil's "Mr. Malty" pitch rate calculator, without clear documentation. My calculations led me to plan on a 500g brick (of US-05) for each of our 5BBL batches, but now I see other brewers pitching that amount for 10BBLs, and half that for 3BBLs.
Assuming 14*P (1.060).... any advice?

[a10t2]

20 billion/gram is a pretty good number. I've done a few counts and they're within 15% of that for US-05. Granted, that was years ago. At 14°P, that works out to around 60 g/bbl if my math is right, for ales (0.75 million/mL-°P).

[freshhoarse]

Ok, so about 300g. Thanks!

[Yeast]

20 billion/gram is a pretty good number. I've done a few counts and they're within 15% of that for US-05. Granted, that was years ago. At 14°P, that works out to around 60 g/bbl if my math is right, for ales (0.75 million/mL-°P).

I would agree.

If you have a scope or would be willing to dish out 150 for something acceptable you could count your yeast and find out with a cheap Chinese hemocytometer and a few pipettes and a couple test tubes or beakers

[Lallemand Caroline]

Hi, I may have some insight into this. I know at Lallemand we can get you the cell count per batch produced if requested. If you contact your rep (or me) they are able to pull the lot certificate of analysis sheets and get you those numbers.
Cheers,
Caroline Parnin
Lallemand Brewing
Siebel Institute of Technology
cparnin@lallemand.com