Ok so how do I know how many cells of yeast I have after washing the yeast cake from a 10 gallon batch?? I cleaned and washed 4 quart size mason jars and place them in the fridge and each one has formed a layer of yeast a little less than a 1/4 full. I need to know how much to add to my starter for my next batch of 1.050 og brown ale
Take another empty jar and fill it with water to the same height as the yeast in the storage jar. Measure the number of Ml of water you have.
Multiply that figure by 3Bn and that is approximately how many cells you have in the jar.
If you had 50ml of yeast then you have around 150bn cells (dead or alive)
Plug that figure into Yeast calc with the date of viability being around when fermentation finished on your brew and it will provide an estimate of how many viable cells there are in your storage jar.
Play with the starter volumes and methods(stirplate etc) until you nail the recommended number of cells to pitch as set in the top of yeastcalc.