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I wondered if anyone who has used the above yeast can give me an idea on the quantity required. I am brewing a fairly high SG IPA (somewhere in the region of 1.065-1.080) batch size 15-20L.

Brewers friend recipe calculator suggests 27g of this yeast based on a 10 billion cells/g density. This is rated at > 6 billion cells/g (which, if i'm calculating correctly, based on the lower estimate of 6 billion cells/g, I would actually need 45g, or 4 packets!!).

I have also seen posts which suggest that 1 packet of this yeast would be ample for a batch this size up to an SG of 1.085?

Any advice would be greatly appreciated as I don't want to under of over yeast!

In case this is needed, I am trying a very basic recipe out (I'm still a newbie);

2-2.5 kg pre-hopped light DME 0.5-1.0 kg dextrose Fermentis US-05 yeast ? g 50-75g Cascade (dry hop) 50-75g Southern Star (dry hop)

Thanks in advance! Gary

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3 Answers 3

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Homebrewers are notoriously underpitching, if you look at it using commercial standards. Two to four packets would be healthy, "commercial grade" pitch. And "commercial grade" is what your yeast calculator is using. Remember, commercial breweries are all about cost reduction / income maximization, so the fact they pitch that many cells means they earn more than they spend on extra yeast - in beer quality and process simplification. Usually you do not want to mimic "cost optimizations" of commercial breweries, but ones that earn you quality and simplicity are good ones to look at.

One packet would be considered underpitching, but my experience shows I usually can get away with it. Good aeration of wort is the key then. Adding yeast nutrient helps.

If you want to be safe, or want to make competition quality beer, 2 packets kept in optimal conditions or 4 kept in acceptable ones are your way. Otherwise, your call.

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  • "the fact they pitch that many cells means they earn more than they spend on extra yeast" Given that the overwhelming majority of commercial fermentations are pitched with yeast from a previous batch and every batch will generate roughly two to five times more healthy yeast than is needed to pitch a single batch, I have to disagree with your notion of 'commercial grade' pitch rates being a matter of cost reduction or optimization. With a large excess of yeast it doesn't really cost anything extra to pitch more, and you're pretty much free to pitch at whatever rate is ideal for the beer.
    – Franklin P Combs
    Apr 29, 2016 at 1:59
  • @FranklinPCombs I wrote "cost reduction / income maximization". Pitch at ideal rate sure increases worth of finished beer. And small breweries in my country are doing that even with single batch brews anyway.
    – Mołot
    Apr 29, 2016 at 6:05
  • Sure, I've seen small breweries that pitch new dry yeast each batch, and I agree that pitching at the ideal rate should increase the worth of the beer by increasing its quality. I just don't think it's as simple as saying commercial breweries are able to do it mainly because doing so makes them more money in return. And if you're saying that that return is due mostly to the resulting quality of the product, I can't see a reason to differentiate between commercial and home-brew pitching rates. Then it's just an ideal pitch rate in general.
    – Franklin P Combs
    Apr 29, 2016 at 22:01
  • @FranklinPCombs in no sentence I say it's not general optimal pitch rate. All I say is that home brewers are notoriously underpitch.
    – Mołot
    Apr 29, 2016 at 22:07
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As a rule of thumb, I work on 1 gram of dried yeast per litre of wort. Has worked for me for the past 3 years. When using packets of yeast, I would simply sprinkle a whole 11.5 gram packet into my 10 litres of wort. Last year I purchased a 500gram package of S-04, so I simply measure out on my digital scales 10 grams of yeast per 10 litre brew. There is plenty of guidance information on the Fermentis website, so check there if in any doubt.

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If you're making a 5 gallon batch at projected ABV of 5 to 6%, then 1 packet of yeast is fine. If your making a beer stronger than 6%, pitch 2 packs. I've been using dry yeast packs for years and love the US-05. Brewdog333

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