You'll buy your yeast in various containers, like sachets, pouches, tubes, etc. So it's however many of those.

Each manufacturer puts a different amount of yeast into their container. That means checking with the manufacturer how many cells they're putting in their container and then using the yeast and pitching rate calculator to work out how many of each container you need for a particular batch. 6.2 containers is probably going to be too many, but it depends on the recipe.

 

What Mark said or you can just eyeball most of your 5 gallon batches with an abv around 4.5 to 5 % with an 11 gram sachet and get in the ballpark.

 

@Ward Chillington is on the mark. Yeast producers package the yeast for use in the most common size batch, that of the 5 gallon bucket.

Keep in mind that the yeast amount doesn’t need to be a precise measurement like the other ingredients. Yeast is a living creature and will try to adjust to the conditions. If you only pitch 2/3 of a pack of US-05 in a wort with an OG of 1.050, you will likely not notice any difference. However, high gravity beers usually benefit from more yeast as do lagers.

As a final note, most brewers using liquid yeast will make a starter to increase the number of yeast cells and improve the viability at a much lower cost than using multiple packages.

 

In the Recipe Builder, the yeast section should also say how many cells are needed. Compare this to what the yeast supplier says is in the package and proceed accordingly.

For ales in 5-gallon batches, one 'package' of yeast is generally sufficient, particularly of the gravity is 1.060 or less. For lagers, somewhat more is needed, a single package is almost always not sufficient.

There is considerable debate about how much yeast is really in a package, be aware. But 100 Billion is a good working number, even if Fermentis claims about 70 Billion in an 11 gram package.

Underpitching yeast usually results in a slow fermentation, and the production of esters giving flavors and aromas that may or may not be desired. Overpitching usually results in the opposite, faster fermentation and 'clean' beer, and if often considered less harmful than underpitching. Temperature also has a large impact, for example underpitching a lager and trying to ferment very cold is sure to cause a very long fermentation.

Best of luck, and let us know any other questions.

 

Hence the Monks calling it "Goddisgood" before they knew that it was just a single cell animal

@Donoroto " In the Recipe Builder, the yeast section should also say how many cells are needed."

Us nubes too new to know to fiddle with microbiology that just wanted beer played with proportions! I thought 'Hmmm..they gave me 1 packet to make 5 gallons....what's 11 grams divided by 5?" Only now some 3 years down this bunny hole of brewing have I begun to understand and appreciate the value of tools like that for building starters and such.

 

Like my subtitle sez: Aint yeast wonderful?