Pitching Rate

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Edd

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Hi All,

Just been looking at some info on Safale S04 yeast and notice that on one description for the yeast it gives a "Pitching rate of 50g/hl to 80g/hl"

What does this mean ? :hmm:
 
There is quite a lot of information and discussion on the web and in books about proper yeast pitching rates. Maybe it is the wealth of information that makes it so confusing, but I run into many people that are completely confused about how much yeast they should pitch. Hopefully, the following won't just add more confusion, but instead it will make it a little easier to understand the math behind pitching rates and what is really required.

Ales & Lagers

The general consensus on pitching rates is that you want to pitch around 1 million cells of viable yeast, for every milliliter of wort, for every degree plato. A little less for an ale, a little more for a lager. George Fix states about 1.5 million for a lager and 0.75 million for an ale in his book, An Analysis of Brewing Techniques. Other literature cites a slightly higher amount. I'm going with Fix's numbers and that is what the pitching calculator uses.

The Math

If you're curious, here is the simple math to calculate the number of cells needed. For an ale, you want to pitch around 0.75 million cells of viable yeast (0.75 million for an ale, 1.5 million for a lager), for every milliliter of wort, for every degree plato.

(0.75 million) X (milliliters of wort) X (degrees Plato of the wort)



There is about 3785 milliliters in a gallon. There are about 20,000 milliliters in 5.25 gallons
A degree Plato is about 1.004 of original gravity. Just divide the OG by 4 to get Plato (e.g., 1.048 is 12 degrees Plato).


So, for a 1.048 wort pitching into 5.25 gallons you need about 180 billion cells.

(750,000) X (20,000) X (12) = 180,000,000,000

As an easy to remember rough estimate, you need about 15 billion cells for each degree Plato or about 4 billion cells for each point of OG when pitching into a little over 5 gallons of wort. If you want a quick way of doing a back of the envelope estimate, that is really close to 0.75 billion cells for each point of gravity per gallon of wort. Double that to 1.5 billion for a lager

Pitching rate = how much yeast to use :D

Oh the wonders of Google!
 
I think those rates are grams per hectolitre so divide by 100 to get grams per litre, so 0.5-0.8g per litre

If we multiply by 23 for a standard 23l brew length we get a pitching rate of 11.5g to 18.4g per brew. Generally people use one 12g pack for convenience.
 
Thanks Guys,

I'll be sure to count out my 15 billion yeast cells in my next brew..... :shock:

Or maybe I'll stick to the single 12g packet.
 

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