Two really stupid noob questions:

  1. I purchased a one-gallon summer wheat beer kit on ebay. It lacks the yeast packet. From what I read, I need 0.2 ounces of brewer's yeast. And I don't have a scale that sensitive. How much yeast is this by volume? I see references to packets on here; I have a ziploc from my local brewer so that's not a useful measurement for me.

  2. The last batch I made with expired yeast didn't ferment well, so at three weeks I added about a teaspoon of brewer's. Even after a good shake, it rose to the top and sat there. Granted, it's been hot. But the dead baking yeast didn't do that. Should I abandon my brewer's yeast (which is fresh) and use active dry? And if so, same question as #1: how much? I get 5/6 teaspoon from my own calculations but don't want to waste another batch.

Thanks in advance.

  • Just so you know- you basically cannot add too much yeast. It's almost impossible. So err on the side of too much over too little, as only too little yeast will negatively impact your beer. Also- when you say "Brewers Yeast" are you using a tub of what you buy at the store? If so, that yeast is not actually rated to ferment beer.
    – rob
    Commented Oct 6, 2020 at 14:18
  • partly agree with rob above, the first part is fine +1 but the second part "yeast is not actually rated to ferment beer" -1, yeast is yeast, for beer use ANYTHING, hell use bread yeast, it works. Between the different yeasts they have different alcohol tolerances and 'flavour profiles'. they all eat sugars and poop good stuff...
    – Sparki
    Commented Oct 8, 2020 at 10:49
  • As a rule of thumb, i agree that too much yeast needs generally a big amount to be a bad thing, however, overpitching can be a bad thing, Chris White of White Labs says: "If the beer is overpitched, yeast do not grow though a complete growth cycle. This results in few new yeast cells, which makes for unhealthy yeast and low viability by the end of fermentation."
    – JeanMi
    Commented Oct 9, 2020 at 6:40
  • As for yeast strains, yes, yeast is yeast, however, brewers strains have been specifically selected for there alcohol resistance, capacity to produce alcohol and/or flavor profile, a random baker's yeast will eventually produce some kind of beers, but probably not something exceptional.
    – JeanMi
    Commented Oct 9, 2020 at 6:40
  • @JeanMi I don't disagree overpitching is bad, but I'm saying it's effectively impossible for one to over-pitch unless 1/3 of the volume of a fermenter is pure yeast slurry, you can add ten packs of dry yeast or white labs vials to a 3 gallon batch and it isn't an overpitch.
    – rob
    Commented Oct 20, 2020 at 20:44

2 Answers 2


The general rule of thumb:

  • Upto and including 3 gal, 2.5 grams or 0.0882 ounce (half packet, by eye)
  • Over 3 gal under 5 gal, 5 grams or 0.176 ounce (whole packet)
  • Over 5 gal work it out from the above.

It is not rocket science, let's be honest this is home brew and as it works and as the end product is drinkable, who cares...

Ale/beer has been around for 5000+ years they didn't really measure out 0.0882 ounces.

The more yeast you add the faster and more vigorous it will ferment (to a point)

You do need to be taking hydrometer readings, this is the only way to tell if it has started fermenting, still going or finished.

Dried yeast will keep for years, if kept dry and out of sunlight!!

I have never re-hydrated yeast or done starters, except in the case of a stalled ferment. Everything I have every brewed has been at least drinkable, Your brew and yeast cannot read and it may need a little longer than what the recipe or packet says, it may not go to your ideal plan but as long as you take hydrometer readings and taste it, you cannot go too far wrong.



The amount of yeast that you inoculate in your wort is refereed to as the "pitch rate", meaning the number of yeast cells / mL / °P in your wort. To calculate the amount of yeast you need in your wort, you can use an online calculator like the one of brewer's friend ( https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/ )

That being said, for 1 gallon of beer you can usually get away with half a package of dry yeast (11g/2 = 5.5g ~ 5g), that's a pitch rate of 1cells / mL / °P, which is usually what you should aim for.

If you are using the yeast from a ziplock of your local brewery, it is going to be hard to say, since you don't have the cell density of the slurry in the ziplock. Best thing would be to ask your local brewer how much he puts in his wort or how much he would put considering your situation.


First comment, would be to always re-hydrate your yeast in sterile water before pitching. Pitching dry yeast in wort results in most of the cells dying immediately. Second, do not aerate your wort(= shake) when it is already multiple weeks in fermentation, that can lead to various off flavors from oxydation

Different yeast have different floculation properties, it is hard to say like this, maybe your did not put enough, or your other yeast is not active enough either.

To ensure not ruining more batches, make sure to always use good yeast before pitching, you can test your yeast by putting some of it in a container with some left over wort or sugary water, before your actual brewing day.

The simplest way to maximize your chances is to get fresh dry brewer's yeast and use the same calculator from above, to pitch the good amount, roughly.

  • Rehydration is not required, presentation from Fermensis in 2019 showed no differences in rehydrated vs directly pitched yeasts. You just run a higher risk of contamination and spend time you don't need to.
    – Mr_road
    Commented Oct 7, 2020 at 20:33
  • 1
    Do you have a source for this ? i'm interested to read about it. I know that now fermensis for example does not require anymore to rehydrate, but this comes down to their modern yeast packaging capabilities (lallemand yeast still recommend it). (e.g. onlinelibrary.wiley.com/doi/epdf/10.1002/… ) Also, in the special case of High gravity beers, i'm not sure direct pitching is really viable ?
    – JeanMi
    Commented Oct 9, 2020 at 6:43
  • It was a live presentation at the Charles Faram Hop Walk, may have been 2018. I don't know of a source but they saw no difference in fermentation profiles between rehydration and direct pitch. And through almost all my home brewing and commercial brewing I have directly pitched and never experienced any negative impat from it, even when brewing 10%+ stouts/barley wines. I have always seen good fermentation profiles. I will see if I can get a copy of the presentaion and permission to share it.
    – Mr_road
    Commented Oct 10, 2020 at 18:09
  • From [Fermensis website][1]: "With E2U™ active dry yeasts, you can pitch directly or rehydrate;..." I don't believe this only appies to their yeast , I have done this with many brands yeasts and always seen good fermentation profiles. [1]: fermentis.com/en/fermentation-solutions/you-create-beer
    – Mr_road
    Commented Oct 10, 2020 at 18:12

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