How do you calculate yeast cells when using dregs?

if you used a starter then you would have the cell count expected for the size of the starter. go to mrmalty for some assumed cell counts.

yeast harvested from a bottle is not different than yeast collected from a smack pack or vial. you could, in theory, begin with one yeast cell and culture that one cell up to pitching volume. in theory and i would not suggest trying.

Cheers.

 

mr malty assumes you are starting with a pack containing 100 billion cells. while you can scale up from less cells, you cant directly apply this calculator unless you know how many cells are in the bottle.

anyone know how to estimate this?

my best guess would be to use the diagram from wyeast's site:

http://www.wyeastlab.com/hb_pitchrates.cfm

ie, cold crash you first starter, use the picture to estimate your cell density, multiply by your volume, and you've got a cell count. i would then plug in those numbers into this calculator:

http://www.yeastcalc.com/indexupdate.html

in order to scale up for pitching. or, you can do as palmer does:

Harvesting yeast from a bottle conditioned beer is quite simple.
Step 1. After opening the bottle, thoroughly clean the bottle neck and opening with sanitizer to prevent bacterial contamination.
Step 2. Simply pour the beer into a glass as you would normally, leaving the yeast layer on the bottom of the bottle intact.
Step 3. Swirl up the sediment with the beer remaining in the bottle and pour the yeast sediment into a prepared starter solution as described in the previous section- Preparing a Liquid Yeast Starter.
For best results, add the sediment from 2-3 bottles and be sure to use the freshest beer you can find. The starter should behave the same as any other liquid yeast pack starter, though it may take longer to build due to the smaller amount of yeast that you start out with. In fact, you may not notice any activity in the starter for the first couple wort additions until the amount of yeast builds to higher levels. Add more wort as necessary to build the yeast slurry to pitching level.

 

I would suggest using Mr. Malty's "Pitching From slurry" tab and make some guesstimates. I guess yeastcalc.com and adjust the beginning cell count I guess.