How many yeast cells do I have?

might be a stupid question but…I am in the process of fermenting an IPA that uses US-05, and was planning on getting a cream ale that uses the same yeast. If I wash the yeast from the IPA and use it in the cream ale, without spending thousands of dollars getting tons of equipment or a microscope to painstakingly manually count my yeast cells, how can I tell I have enough yeast? How To Brew briefly goes over washing, or ranching, but doesnt say exactly how to tell you if you have enough if you do this. Is it just eye balled??

.060 OG IPA will take about 300 ml slurry. There are online pitch rate calculators you can use. Brewers friend is the one I use.

I harvest yeast but don’t wash/rinse it anymore. I just swirl up the contents of the primary fermentor after racking to the bottling bucket and pour into a sanitized quart mason jar. I had been estimating 2 billion cells per milliliter but may go to 3 billion. This is for my harvested yeast though. I do filter out the hop debris during the pour from the boil kettle to the fermentor.

Link to post on washing and not washing. Collecting, rinsing and reusing yeast - #6 by brew_cat

A picture of your harvested yeast after it has compacted in the refrigerator would help. Cells per milliliter depends upon how much non yeast material is mixed with your harvested yeast.

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I havent harvested the IPA yet. I still have 1-2 weeks in primary before i move to secondary for dry hopping. Im trying to get an idea of how much I should save. I dont want to save it all if I dont have to. I also dont want to add to much yeast.

Fill a quart jar and use what you need when you brew again. The remainder can be tossed out or use some more of the yeast in a month or two.

In your situation my MO would be: on your next brew day rack off the IPA, pour out about half the yeast cake to save for future use, pour the new chilled wort onto the other half. Done.

I agree with @flars and @dannyboy. If you don’t have time to brew before you rack, dump the yeast in a sanitized mason jar. Cover it with Saran Wrap, and put a rubberband around the neck. That should be plenty to get your next batch going, as long as it’s used quickly. If you can time it out, Danny’s method is great! It is very hard to over pitch so don’t worry too much about that.

If you have to save the yeast for a while (2 months+) I would suggest making a starter to get those yeast up and running. Nice part is it can be small since you’re pitching such a large slurry.

Depending on when my kits ship from NB, I’ll be brewing again this weekend or next. I started using hop bags for my additions on the IPA, and straining as it goes into the fermenter, not a lot of junk any more. I’ll save half for the cream ale, and store the rest, just in case. Thanks all.