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-   -   Pitching Rate Question (http://www.homebrewtalk.com/f163/pitching-rate-question-167790/)

dennyb 03-12-2010 02:00 PM

Pitching Rate Question
Hello everyone, I have read the forum for quite some time, but this is my first post.

I will be making a Scotch Ale this weekend with an expected OG of 1.083. I just did the math for the starter and came up with about 295billion cells needed for the pitch. That's close to a gallon of starter for a 5 gallon batch, which just seems excessive to me. I normally brew in the 1.050 to 1.060 range, for which I like to use a one liter starter. If you all would be so kind as to check my math, I just can't imagine dumping a gallon starter in to a 5 gallon batch.

Thanks a bunch.


samc 03-12-2010 02:17 PM


decant the liquid off the yeast

wizardofza 03-12-2010 02:30 PM

Instead of regurgitating the info in the article, this is a great read:


dennyb 03-12-2010 02:43 PM

Awesome, that shows 2.5L which seems more accurate to me. I'll definitely defer to that calculator, but I wonder why it is so different from what I came up with? At a little over half as much volume it seems like I may have some figures wrong, or that my formula is just too riddled with estimates.

I was under the impression that a 2L starter is good to about double the amount of yeast in a vial (to around 200billion cells). Is that just an incorrect constant that I picked up somewhere?

Here are the constants I use to calculate the amount of yeast to pitch:

750,000cells per milliliter of wort.
5gallons = 18,925ml
Deg Plato -->1.082-->(83/4) = 20.75
2L starter will yield 2(original pitch)

dennyb 03-12-2010 02:48 PM


I have that article, it is that formula that I used to generate the original size of the starter. I'm really just curious as to why it is different.

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