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It seems that there are varying opinions about the size your starter should be. What is the basic rule-of-thumb for 5 and 10 gallon batches?

  • How much water should be used?
  • How much malt/malt extract should be used?
  • How much time should the starter have to develop, and does this vary depending on the method (coke bottle with the occasional shake vs. stir plate)?
  • What characteristics can too much/too little yeast yield?
  • Are these amounts different for dry yeast, smack packs, and vials?
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1 Answer

up vote 11 down vote accepted

Your starter size will vary with the cell count you are shooting for, which in turn will be determined by the original gravity of the wort, batch size, and whether it is an ale or a lager. Use Jamil Zainasheff's pitching rate calculator to determine how much yeast to pitch.

As an easy to remember rule of thumb, use 10 grams of dry malt extract for every 100ml of water. This will give you a roughly 1.040 starter, which is good for growing yeast even if your wort will be higher or lower.

Starters made from healthy yeast packages will be ready to use in 12-18 hours, just pitch the starter or build it up again with more DME+water.

Using a stir plate will pull more oxygen into the starter, which will give you more yeast reproduction and get you to a higher cell count.

Too little yeast can lead to longer fermentation times, under-attenuation, and off-flavors from stressed yeast.

Liquid yeasts (vial or smackpack) can be treated the same, and dry yeast does not require making a starter (just use the correct amount. It's cheaper and easier to buy more dry yeast than to build it up with a starter).

For a typical 5 gallon batch of ale, you would be looking to make a 1 liter starter from a vial/package of liquid yeast. Double that for a lager.

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Good answer to an involved question –  brewchez Sep 23 '10 at 14:54
Does your rule of thumb of 1 liter per 5 gallons scale linearly with batch size? For example, do you recommend 2 liters of starter for a 10 gallon batch and 0.2 liters for a one gallon batch? –  Bill Sep 30 '10 at 3:44
It's all about cell count, so assuming good yeast viability in your vial/smackpack, it should scale linearly (for homebrew purposes, at least). You would never need to make a starter for a 1 gallon batch as liquid yeast is generally good enough for 2-3 gallons and less directly out of the package. –  Bil Sep 30 '10 at 18:39
And what is the effect of too much yeast? That went missing on the answer. –  Cleber Goncalves Mar 12 '13 at 13:11
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