How to Make a Yeast Starter

May 11,2010 by 55 Comments

Yeast Starter Kit Homebrewing

I highly recommend the yeast starter kit from which includes a 2000ml flask (the size you want), dried malt extract, and yeast nutrient. Go check it out on

Making a yeast starter is one of the best homebrewing techniques for improving your beer. While not absolutely necessary, starters can really take your beer to the next level.

If you already brew, making a yeast starter is a piece of cake. Here is why you do it, and how to make a yeast starter:

What is a Yeast Starter?

A yeast starter is essentially a mini batch of beer. The difference is that whereas you brew a batch of beer to have a tasty beverage, you make a yeast starter to make more yeast. So while you need to take into account flavor and aroma when brewing, the only thing you need to focus on with a starter is growing healthy yeast.

You make a yeast starter in order to:

  1. Grow enough healthy yeast to properly ferment your beer. Pitching a larger amount of yeast will ensure a quick and complete fermentation, prevent off-flavors, and lead to all around better tasting beer.
  2. Prepare the yeast for fermentation. Yeast that have been sitting in the refrigerator for months are dormant. A starter will activate the yeast and get them ready to start fermenting beer.
  3. A starter is a way to proof your yeast. If you have yeast that has been sitting around for a long time, you want to make sure it is still viable. If it is completely dead, you’d rather find out in a starter than in a 5 gallon batch of beer.

What Yeast to Use?

Starters should only be made for liquid yeast cultures. Dried yeast packs already contain enough cells (220-230 billion) to inoculate a 5 gallon batch, so it is not necessary to grow them. Simply rehydrate the dry yeast according the the manufacturer’s instructions.

The most common liquid yeasts are the Wyeast Activator Smack Pack and the White Labs vials. Each of these contain roughly 100 billion cells, but you’ll want about 200 billion for a typical 5 gallon batch of ale. The starter will get you there.

Starter Size

The size of the starter depends on the beer that you’re making. Higher gravity beers and lagers require bigger starters.  Check out my post where I go into more depth about the proper yeast starter size where I give a video walk-through of the Mr. Malty pitching rate calculator.

If you’re brewing a beer with a high starting gravity (1.065+), a lager, or have old yeast, then I suggest you use the calculator to figure out the correct size. For a standard gravity ale, you’re safe with a 1 liter starter.

Wort Size
The size of the starter refers to the amount of wort (water + DME) in the container after the wort is boiled and cooled. This means that you should put slightly more water into the pot than you want to end up with because a portion will boil off. You are only boiling for 15 minutes, so it won’t be much.  I add 100-200 ml extra to a 1 liter starter and it ends up very close. Experience is key here, but it doesn’t need to be perfect.

Amount of DME to Use
The starting gravity of the starter wort should be between 1.030-1.040. There is a very simple metric ratio you can use that will get you there: 1 gram DME for every 10 ml wort (after boiling). So using the 10 to 1 ratio, a 1 liter starter requires 100 grams of DME.

Dried Malt Extract Weight to Volume Conversions
You might not have a scale, which makes weighing the DME pretty tough. While measuring DME in weight is always better than measuring in volume, if all you have is standard measuring cups then you can use the conversions I’ve measured out for you. Keep in mind these were taken with the cup filled to the brim and after tapping the side to fit more DME. It’s not perfect, but will get you close enough.

1/4 cup = 33 grams

1/2 cup = 66 grams

3/4 cup = 99 grams

1 cup = 132 grams

So for example: If you are making a 1 liter starter and using the recommended ratio of 1 g DME to 10 ml, then you would need 100 grams. Working with cups, you would add 3/4 cups.

Equipment needed

  • Saucepan or pot. At least twice the size of the starter liquid volume is ideal because you are going to get significant foaming, just like in brewing beer.
  • Large glass container for making the starter. I use an 2 liter Erlenmeyer flask, but you could also use a growler or large mason jar. Clear is better because you can see the starter activity. The size depends on what size starter you are making, but 2 liters (~ 1/2 gallon) will do for most of your starters.
  • Liquid yeast, either White Labs or Wyeast.
  • Light Dried Malt Extract (DME).
  • Egg whisk.
  • Scale for weighing DME.
  • Thermometer.
  • Sanitizer (I use Star-San).
  • Ice.
  • Aluminum foil, cut into a square that will cover the top of your starter container.


  1. Measure out your DME and place it aside.
  2. Measure out your water and pour it into the pot; turn the burner on high.
  3. When the water starts to boil, dump in the DME and stir vigorously with the whisk in order to break up clumps. Boil for 15 minutes
  4. While the wort is boiling, prepare your sanitizing solution and sanitize your pot lid, thermometer, funnel, yeast package, aluminum foil, and starter vessel.
  5. Near the end of the boil, prepare an ice bath in your sink to cool the wort.
  6. After 15 minutes of boiling, remove the pot from the stove, place it in the ice bath, and cover with the lid.
  7. Check the wort temperature with your thermometer. When it reaches 70-75 F, remove it from the ice bath. Cooling will take about 10 minutes.
  8. Pour the wort into the starter vessel using the funnel and cover loosely with foil.
  9. Add the yeast and swirl vigorously for 30 seconds, being careful not to spill.
  10. Place the starter somewhere where it won’t be knocked over.  It doesn’t need to be protected from light the way a batch of beer does.
  11. Add oxygen. You can do this using a stir plate or just give it a shake as often as possible for those first 24 hours.
  12. After 18-36 hours your starter will be done fermenting. You can either pitch it at this point into a fresh batch of beer, or if you are not yet ready to brew you can put it in the fridge until brew day. If this is the case, see the additional steps. Otherwise, you’re done!

Additional steps if you are storing the starter in the refrigerator until brew day:

  1. Store the starter in the refrigerator to let the yeast settle out of the wort and form a layer on the bottom.
  2. On brew day, take the starter out of the refrigerator and decant (pour off) the wort down the drain, while being careful to leave behind the yeast cake. Leave about a 1/2 inch of wort in the vessel so you can stir up the yeast. Give it a swirl and set aside. Let the starter come up to room temperature before pitching. Taking it out of the refrigerator 3-5 hours before you pitch is a safe bet.
  3. When your cooled wort is in the fermentor and you are ready to pitch your yeast, give the starter one final swirl and pitch it into the wort.  You are done!

Important Notes and Common Questions

  • Sanitation is key to the whole process. If you screw this one up, not only will you infect your starter, but you’ll infect and ruin the batch of beer that you pour it into. Be very, very, careful.
  • Hops do not need to be added to the starter. Remember we are making yeast, not beer. Some people add hops, but in my opinion it is an unnecessary step.
  • “Do I pour in the whole starter or decant?” A very good question. It really depends. If you are using a large starter ( 2L+) or are making a lighter beer where the starter could affect the flavor, then I recommend you decant. If you are making an 8% stout then you won’t notice the extra wort mixed in with the complexity of other flavors.  If you do choose to decant, make sure you chill the starter to get the yeast out of suspension. Otherwise, you will pour yeast down the drain with the wort.
  • You don’t need a stir-plate to make a starter, but they are a good idea. What you do need however, is oxygen. Simply shaking the starter vessel every couple hours will get you results that are almost as good as the stir-plate.
  • Do not use an airlock. You want oxygen exchange between the liquid and air so all that is needed is loose fitting aluminum foil. This will allow oxygen to enter the vessel, but keep bugs out.
  • It is a good idea to add yeast nutrient to the starter to help promote yeast growth, however, I usually fail to follow my own advice on this one. There are minerals in the DME that will provide yeast nutrients. Additional nutrients do help, but they are not necessary.
  • “How long will my starter last?” The sooner you use your starter the better. The longer you wait, the more yeast cells die off and the starter becomes less effective. Try to use it within a week. If you wait longer, you should use that yeast to make another starter.

Additional Resources

Do you make yeast starters? Have any tips or questions?

About Billy Broas

He is the founder of The Homebrew Academy, a BJCP beer judge, and the homebrewing expert on the Rocky Mountain PBS television show Colorado Brews. He lives in the fine beer town of Denver, Colorado.

55 responses to “How to Make a Yeast Starter”

  1. SudsyMaggie says:

    Very nicely written! Sure wish I would have had this for reference when I started making starters earlier this year.


  2. OtownPyle says:

    Well crap no air lock huh? Man I swear I get all kinds of diff information.. I did that the first time I did a yeast starter, but then my local buddies said they all use airlocks on starters so I got nervous and swapped to airlock & bung… And I was told it needed to be in a dark low lit area as well…I’m just gonna stick to what you tell me…haha Thanks great vid
    .-= OtownPyle´s last blog ..OTownPyle: RT @ChrisVernonShow: could people in Clev. be watchin LeBron last home game? if they play like they did in 2qtr they are =-.

  3. Billy Broas says:

    @SudsyMaggie Thanks Maggie. I’m pretty sure when I started making them I was using twice as much DME as I as supposed to. Live and learn..

    @OtownPyle That’s brewing for ya man. Everyone has a different method. Here’s my reasoning..An airlock is like a one way valve. It’s going to let CO2 out but no O2 in. You need O2 for the yeast but unlike a batch of beer, it’s not going to harm the taste since it’s so little wort and you usually decant anyways. For the light, that is only harmful if you have hops in your beer which causes it to become “lightstruck” and skunky.

  4. chris starr says:

    Spot on! The only thing I do in addition for starters is add a bit of yeast nutrient. It’s not needed, but I usually have some on hand for my meads and ciders, and I’ve found they take off a few hours sooner than without. (which usually isn’t a big deal since I’m almost ALWAYS doing what you do and storing in fridge until brew day! You know how daily life usually get’s in the way of brew day!)

    That being said, I’ve only recently gotten back into starters (in the early 90’s I did starts for any liquid culture & even a few dry cultures) and usually reserve this step for “big” beers… OR if I plan on “harvesting & washing” a culture from a previous batch.

    Hey this may be your next topic! Harvesting Washing and Storing yeast from a batch!
    Keep up the good work!

    Chris from HBT! (starrfish)

  5. dr dean says:

    Billy, great video! Been a couple of years since I made a batch of wheat! Makes me want to go get my stuff out of the closet!
    .-= dr dean´s last blog ..Money and Marriage: Marital Bliss or Beast? =-.

  6. mike says:

    Nice video man.

    I feel a little bad though, I have this same video subject listed in my queue as well. Hope it turns out as good as your did.

    Very good information and the quality is much better than 90% of the crap out there. I enjoy making videos as well. That, and designing good how to’s. So much of this information is wrapped up in technical drawings and words. I’m a pretty visual guy and I like to look at content and just know what I am looking at without having to sift through it.

    Great video. I’ll definitely be coming back. I tried signing up for the book/newsletter and I haven’t gotten a confirmation email yet. Just an FYI.

    Mike’s Brew Review

  7. Billy Broas says:

    @Mike Thanks for the compliments Mike. Don’t feel bad at all, I’m glad you’re doing one also. The thing about brewing is that there are so many ways to do it so it’s best to have different perspectives. The more of us that get good brewing information out there the better IMO.

    Your site looks great. We’re definitely similar in that we’re visual people. I love reading but when it comes to something as hands on as brewing, I learn 100X better when I see it done.

    Looks like the email went through. Sometimes it takes a minute. Thanks for stopping by and I’ll be around yours as well.

  8. Nigel says:

    Hey Billy,

    As usual, very nicely done. BUT…and this may be a big but(t–haha), in the Steps 1-12 typed out above, you don’t advise when to add the yeast!! In the vid, it’s clear, but you seem to have skipped this in the written-out steps.

    I, personally, know when to add the yeast, but you may want to go back and amend the steps for newer brewers. :) Just sayin’.

    Fine video, though. Keep at it!

  9. Billy Broas says:

    @Good catch Nigel! Thanks for staying on top of things and please point out my omissions in the future. Glad you like the video.

  10. Aidan says:

    Hello Billy,
    Thanks for another handy video! You specify glass container for fermenting the starter and this is what I’ve seen in other starter instructions that I’ve read. Do you think there would be a problem with using plastic (a sanitised juice bottle)?

    • Billy Broas says:

      Hey Aidan, glad you like the video. Well people ferment in plastic buckets so I don’t see why you couldn’t do a starter in a plastic container. Just make sure there are no scratches in it. Cheers.

  11. Aidan says:

    Thanks for the reply. I think that’s what I’ll do as I don’t have any glass bigger than 1L mason jar. Another thing I was thinking, plenty of extra headspace should be a good thing since oxygen is good for a starter – do you agree?

    • Billy Broas says:

      Yea the headspace is good. Especially for oxygen, but also for room for the krauesen as I was reminded of recently when I had a slight overflow. Also if you need glass, check out the 1 gallon pickle jars at the grocery store. It’s what I use in my yeast washing video.

      • Aidan says:

        The yeast I harvested and made a starter for by following your instructions is working very nicely at the moment. The fermentation took off very fast (within a few hours), and is very active – the most active one I’ve seen so far. (I’ve also added a link to this video on my website –

        One little issue I had with the starter was whenever I shook it up, it would froth up and start fizzing out of the container when I released the lid (I used a loosely fitted lid instead of foil and just tightened it when shaking). This was especially the case once fermentation was starting to kick in. So after that I left it alone without any more shaking. Do you keep shaking it up after fermentation starts?

        • Billy Broas says:

          I do keep shaking it after fermentation starts. It’s actually more of a swirl so I don’t spill. Sometimes it foams over but if it does I don’t really worry about it. It’s more of a mess than a cause for concern. One thing I started doing was making slightly less than a 2L starter because once I added the yeast it would get pretty close to the top. Thanks for the link btw!

  12. Jim says:

    Can’t I simply use the flask and skip the pot? An erlenmeyer flask can be heated directly on the stove (I have a gas stove) and then moved to an ice bath, no? Any reason NOT to do this?

    • Billy Broas says:

      You can boil in the flask and plenty of people do, but I don’t do it because 1) It’s near impossible to stir and break up all the DME chunks and 2) There is very little headspace so a boilover is very likely. I like the extra room a pot provides for when the foam rises.

  13. chris says:

    great vid! if I am making a starter from slurry, mr malty tells me how much yeast I need but not the size of the starter. Tips?

    • Billy Broas says:

      Hey Chris, good question. The slurry calculator doesn’t really care if you make a starter or not, only if you have enough yeast. Instead of tell you a starter size, it tells you how much of your slurry will give you enough cells for your beer. So if you have enough cells in your slurry then you don’t need a starter. I still like to make a starter though, so we you could do is use that calculator to figure out how much of your slurry (in milliliters) would give you 100 billion cells, the same as a white labs vial. Then you would use the starter calculator like usual, pretending that you had a vial of yeast. Hope that makes sense – I haven’t slept much recently. Also check out the comments in the post where we talk about this:


  14. Ed says:

    Hey Billy,

    Thanks for the video. I have one question though: since co2 is heavier than air, wouldn’t it displace any oxygen in the headspace that was getting in under the tinfoil whether you had an airlock or not? I don’t understand why the tinfoil is better than the airlock. Can you explain?

    • Billy Broas says:

      Hey Ed, great question. In the first few hours after you pitch the yeast, there is no CO2 produced as they are in the lag phase, acclimating to their environment and taking up minerals, O2, and amino acids. So during that time there is plenty of opportunity for O2 in the air to get in. The air getting in is just one step though. The important part is agitation on the surface of the liquid which allows the O2 to enter, which is why stirring/shaking is important.

      Once fermentation begins and C02 is being produced it gets a little trickier. Disclaimer – I’m no rocket surgeon, but I THINK what happens is that the vortex created by swirling the flask or using a stirplate forces C02 out and sucks air in. This isn’t possible with an airlock because it is essentially a one-way valve, allowing CO2 out but nothing in.

      If you didn’t agitate the starter I don’t think you’d get as much air entering it, but you’d probably still get some diffusion of air because of the partial pressure gradient between the inside of the starter and the atmosphere. But that’s about the limit of what I know and I’m sure if I said more I’d just put my foot in my mouth lol.

  15. Robyn Moody says:

    Thanks to your video I’ve got a starter 25 hours underway and it’s behaving fine. What signs should I look for to know it’s finished fermenting?

    • Billy Broas says:

      Awesome Robyn. The bulk of your cell growth is already done so I would go ahead and brew if you’re ready. The only way to really know is to take gravity readings, but that’s really not practical or necessary with a starter. Pitch away!

  16. AJ says:

    Thanks for this! Best instructional on creating a yeast starter I have found. Looking forward to getting my starter underway today!

  17. Jason B. says:

    Hi Billy! Great tutorial. Your site is always full of useful information. I’m not new to home brewing but new to using starters having only done it once. I’m having a hard time finding information about this and wanted to get our input. There is not much talk about what temperature to maintain your starter. I was once told that the starter should be maintained at the same temperature you plan to ferment. Do you think this is correct and wise? For instance, I am preparing to brew a Kolsch and will be using Wyeast 2565. This is a hybrid yeast and it’s optimum fermentation temperature is 56 to 64 degrees. My thought was to first cool my starter wort to this temp range, pitch my yeast, and then place the starter in my fermentation chamber which will already be cooled to this range. Do you think this is ideal and will provide the ideal environment for proper cell growth? With a hybrid yeast like this, I would be worried about hurting it or possibly it mutating in some manner if the starter were fermented up at the 72 degree mark. I just don’t know enough about yeast and starters to know what to do here. Can you explain more on starter temperatures and specifically the hybrid style yeasts such as Kolsch and Cali Common? Thanks!

    • Billy Broas says:

      Hey Jason, glad the site has helped you. For your starter, I would still do it at room temperature. The starter is all about cell growth and the yeast are more active at warmer temperatures. You’re not looking to get any of the fermentation characters you would get from fermenting a batch of beer – just growth. 72F is still relatively cool for the yeast. They can handle much warmer temperatures.


  18. Aaron H says:

    I did not see much activity, if any, activity after pitching the yeast. I am making a 1L starter for a Belgian using WhiteLabs Saisson WLP565. This is the first time making a starter. Yeast has flocculated to them bottom, but I expected to see more foam/krausen develop. Is this due to the tin foil letting gases come and go as opposed to be locked in? Just curious if this worked for me before I brew and potentially ruin a batch. Is there a way to test?

    • Billy Broas says:

      Sometimes there is very little activity – just a few bubbles rising to the surface. If you really don’t see anything then you could have a bad vial of yeast, which is one of the reasons to make the starter. Also check the date on the vial to see if it’s old.

  19. Sgt.shultz says:

    I boil my wort in the flask. This cuts back on contact and chance of infection. I also use a stir plate to keep things oxygenated.

    Thanks for the info. I always forget how much DME I need.

  20. Sean says:

    Hi Billy, thanks for the great video and instructions! I’m newer to brewing and going to try a starter for the first time for my next brew. I’m planning on a 10gal batch split over two carboys. I have bought one flask… What would you suggest? Should I brew up one starter, split it into a second flask or jar, let that brew and pitch separately? Or, should I just do the one starter and split evenly on brew day? Thanks in advance for this help and for the continued pointers I get from your site!

    Cheers, Sean.

  21. Joe says:

    Thanks for the info. This is my first time making a starter. I followed your instructions for the DME/water ratio since I don’t have a scale. I noticed that I had significant boil off. I started with 2L and by the time I put in my flask is was down to 1.5L. Should I top it off to 2L with sanitized water? I was thinking that I should since I took a gravity reading and it seemed on the high side ~1.049.


    • Billy Broas says:

      It’s not a huge deal but I would top off it off. If you were off by 100ml that’d be one thing but 500ml is a bit more than I’d be comfortable with. Good luck!

  22. FedoraDave says:

    I appreciate the video very much. I’ve read about yeast starters, and have made them for a couple of batches, but with mixed success (my yeast on one may have been old/defunct). But reading about a procedure and seeing it done are two different things, and I find seeing how a process is done helps me more. This was very informative, and I’ll be referring to it this evening when I make a starter for the IPA I’m brewing Sunday.

  23. ROW says:

    Hey Bill, thanks a pant-load for your vids. Great references- I watch this and step-up a couple times a year just to check my stats. Q: How about using LME??? I have ~~3lbs of Sorghum LME and would love to use it for a starter. Can’t see it being an issue, but don’t know ratios, etc. Any advice??? Thanks again for your great work!

  24. Tony M says:

    Great information. I had a question about secondary storage in the fridge until brew day. Should this be done only with the tinfoil on top or should it be air sealed?

  25. Mark says:

    I watched your video on yeast washing.That is something I am very interested in.I do have a question once your yeast is washed and in frig when you go to brew do you just dump the yeast into the primary or do you need to use a yeast starter as well using the reclaimed yeast.
    Thanks Mark

  26. Jose says:

    Is there an advantage to increasing the size of the starter with more wort AFTER the yeast has been pitched? Thanks for the great post.

    • Billy Broas says:

      Hmm I can’t think of why that would be better than adding it before. You’ll get diminishing returns on growth the more wort you add to given amount of yeast.

  27. Jose Ceja says:

    OK, thanks for the response and the great article.

    I’m going to attempt a lager and need to make a very large starter (4L). Any specific tips on making a starter that size?

  28. Norm says:

    Maybe I missed something even after watching twice. You add the starter but leave off the cake on the bottom. You refrigerate and mix then add it. What changed?
    What is the difference then adding it ALL the first time?

    • Billy Broas says:

      I’m not sure I follow your question. I dump most of the wort down the sink and then add the yeast cake and a little bit of wort to the beer.

  29. mark says:

    First time using a starter. Thanks for the clear, straightforward vid! Only question left is… “is there any need to add additional yeast after pitching starter into beer?”

    • Billy Broas says:

      Not if you properly calculate your yeast needs ahead of time, unless you are doing something special like adding brettanomyces.

  30. Nilzie says:

    Hey, thanks for a great article.

    I’m using a belgian ale yeast, that works on top of the wort. When it’s peaking (when I guess the most yeast bacteria will be alive and kicking), I guess all of the yeast that I want for my batch will stay on top of the wort. Do you think it will be ok to skim the active yeast from the top instead of waiting for the (dormant?) yeast to sink to the bottom?

    • Billy Broas says:

      All ale yeasts are top fermenting and create a foamy layer at the top of the wort. At the same time the yeast (ale or lager) is distributed throughout the fermenter during fermentation – it’s not all at the top. For starters, you have two options: 1) Pitch the entire thing into the fermenter, 2)Chill the starter so all the yeast sinks to the bottom, decant the wort, then pitch the yeast cake.

      Edit: Also, “yeast bacteria” is the wrong term. They are two separate organisms. You want yeast in your beer, but definitely not bacteria!

  31. Marios says:

    Hi Billy thank you for the very informative video.

    I am planning to make a 3.5L starter and I wanted to ask how long should I let it ferment before storing in the fridge?

    Thank you!

  32. Erik says:

    Hi! Its my first time attempting to grow yeast from harvested commercial yeast. My question is, everytime when im adding new wort, do i add the wort into the starter or decant the yeast and att that to a new starter? with starter i mean new wort with 1030 gravity…

    • Billy Broas says:

      Hey Erik, if the yeast is already in a starter vessel (e.g. you’re stepping up a starter) I would add the fresh wort directly on top of the yeast cake.

  33. Paul Johnson says:

    Thanks for the article! One question I have. I did a 1 Liter starter with 100 grams of DME (3/4), and afterwards did some research and everything I am reading shows that 3/4 cups is actually equivalent to 200 grams for a 2 liter starter. 200 grams comes out to (specifically) 0.84535 cups which is just over 3/4 cups. So, when you are saying 100 grams is 3/4 cups, is that just a typo? Shouldn’t it read 100 grams = .422 cups (or just under 1/2) and 200 grams = just over 3/4 cup DME? Or am I just reading it wrong?

  34. Paul Johnson says:

    Billy- sorry- please disregard my last post. Looks like I am just not understanding the weight and volume conversion. looks like all the calculators are using water which is not the same weight which affects the conversion of grams (weight) to cups. DME does seem to be at about 3/4 cup per 100 grams. Thanks for the calculations, and sorry for doubting you!

  35. Dustin Hubbard says:

    Great video and very informative. Could I use the technique you described with 1 wyeast pack for a 10 gallon batch? From my understanding this would take a 2 liter volume and double the DME. Hoping to save a little from buying 2 wyeast packs every brew day.

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