What does 300 billion cells look like?

[stosh]

When you build a fresh starter or harvest yeast from a previous batch, how do you know how many billions of cells there really are say just by looking at what's in front of you?

This would likely apply more to harvesting and building a starter from that and saving part of the harvested starter to use again on the next batch.

 

[flars]

When you build a fresh starter or harvest yeast from a previous batch, how do you know how many billions of cells there really are say just by looking at what's in front of you?

This would likely apply more to harvesting and building a starter from that and saving part of the harvested starter to use again on the next batch.

I use a starter/pitch rate calculator when I use fresh yeast. The one I use all the time for consistency is this one.
http://www.brewunited.com/yeast_calculator.php
A 100 billion cell over build with this calculator will be approximately 25 milliliters of yeast in a pint jar after a few days of compaction in the refrigerator.

I will estimate 2 billion cells per milliliter for clean harvested yeast. I estimate 4 billion cells per ml with WY 3711. Seems to work out. All yeast cells aren't the same size.