yeast washing cell count

I'm attempting my first go at yeast washing. I've read as much as I can about the process, and about making a starter as possible so that I can get pretty close to getting it down right the first time. But my only question is, how can I tell how many yeast cells I have in the washed yeast and/or starter to make sure I am pitching enough?

I'm probably still a little rough on estimating yeast cells in harvested yeast. I've had no fermentation failures though, most likely because I may tend to go more on the over pitch side rather than under pitching.

I use information from this site and estimate 1 billion yeast cells per ml of harvested yeast. This is after the yeast has had a week to a month for compaction.
http://www.woodlandbrew.com/2013/01/yeast-washing-revisited.html

I use the Brewers Friend site for estimating yeast viability, from the production date/harvest date. Also use this site for the pitch rate and starter size calculator.
http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

As an example. 300 ml of yeast harvested 10/24/2014. The yeast is estimated to be 76% viable. 300 ml (300 billion cells) × 0.76 = 228 ml (228 billion cells) or as entered in Brewers Friend, "slurry tab", as having 0.228 liters of yeast with a slurry density of 1 billion cells per ml. BF allows the slurry density figure to be entered by the user.

This is a new calculator recently produced by a HBT member.
http://www.homebrewdad.com/yeast_calculator.php

I have stopped rinsing the harvested yeast. I leave about 10 to 12 ounces of beer in the fermentor. Swirl the yeast into the beer. Lay my carboy on its side, with blocks to prevent rolling. Let the mixture of yeast and trub settle for about 20 minutes and then pour off one full quart. (Hop debris has been filtered out during the pour into the fermentor.)


I hope this is somewhat helpful.

If you get around 4-6 jars of washed yeast usually just one jar is enough to make another 5 gallon batch. You may need to make a starter though, especially if its older then a few weeks. Here are some good links about washing and yeast calculating
https://www.homebrewtalk.com/f163/yeast-washing-illustrated-41768/
http://www.mrmalty.com/calc/calc.html