Ripe Sourdough Starter: What does "ready to use" look like?

Sift’s Spring issue goes into sourdough baking in depth, with articles on sourdough breads and the sweet side of sourdough. To complement those recipes, we’d like to share this Techniques column. How do you know when your sourdough starter is ready to bake with? Let’s take a look.
We’ve answered hundreds of questions on this topic, but in this case it seems some pictures could well be worth a few thousand words.
sourdough Starter

Wake up your sourdough starter

Your starter has been tucked safely in the refrigerator for… awhile. Ten days, maybe longer. It’s separated, with a few tiny bubbles in the bottom, and a layer of grayish-looking alcohol on top. This is the sight that generates a lot of phone calls to our hotline. Can this possibly be OK? Is it dead?

Despite its current uninspiring appearance, this starter is still capable of doing great things.

sourdough Starter

Your sourdough starter’s first meal

Stir everything back together (some people just pour off the top layer, which is OK, too), discard half, and feed the remainder with equal weights of flour (a scant 1 cup, 4 ounces) and water (1/2 cup, 4 ounces). Mix well, cover, and leave on the counter for 12 hours. Repeat the discard and feeding process every 12 hours, leaving the starter on the counter. After a few feedings, you’ll see the starter becoming more and more active, doubling in size in a shorter time.

Looking for ideas of what to do with that discarded starter? Visit this page to get a whole collection of recipe ideas.

sweet sourdough baking via@kingarthurflour

Get ready to bake

This is the same starter after a few days of the regular feedings described above. We stirred, discarded, and fed it with flour and water at 8 a.m. (2 hours ago). Now we’re going to watch its development. See the number and size of the bubbles increasing?sourdough starter via@kingarthurflour

Active, but not ripe, sourdough starter

The same starter at 1 p.m., 5 hours after feeding. It’s beginning to expand, and has many more bubbles. If you watch it for a minute, you can see the bubbles forming and coming to the surface in slow motion. This is an active starter, growing and expanding, producing bubbles of carbon dioxide. But it’s not yet ripe (at the top of its yeast and bacteria growth arc), nor at full strength for raising dough.sourdough starter via@kingarthurflour

Ripe and ready to go

The same starter at 4 p.m., 8 hours after feeding. It’s doubled in volume, and shows signs of just beginning to sag under its own weight. This is active starter that’s also ripe, ready to be added to bread dough to perform its sourdough magic. After mixing it into dough, then some rising and folding, the dough can be shaped and refrigerated overnight to be baked tomorrow.

sourdough Starter

The best way to measure sourdough starter

An important thing to note about measuring sourdough starter: The more bubbles in it, the less a cup of active, ripe starter weighs. Measuring by volume can mean you have more or less starter in your cup, depending on where it is on its growth curve. That’s not a deal breaker for your recipe, but having a different amount of starter than called for may change the rising times and finished size of your loaf. To be sure you have the lifting power you need, measuring ripe starter by weight is always a better choice.

Once you gain confidence that your starter is vigorous, you can move its “get ready” feeding to the evening, knowing your starter will be ripe next morning to mix into your dough.

Your sourdough baking adventures await. We have lots of ideas (more than 150 recipes) to help you navigate this tasty and rewarding style of baking. Be sure to visit our sourdough guide for more in-depth information about creating, maintaining, and baking with sourdough.

At Sift, we live and breathe baking, and hope you’ll join us. Baking together is always more fun.

Susan Reid

Chef Susan Reid grew up in New Jersey, graduated from Bates College and the Culinary Institute of America, and is presently the Food Editor of Sift magazine. She does demos, appearances, and answers food (and baking) questions from all quarters.


  1. Deborah Nicholson

    I forgot to save some of my sour dough for starter. Can I use some of my bread dough to make a new starter. It has whole wheat flour, fennel seed and quinoa in it as well as all purpose flour.

    1. The Baker's Hotline

      Hi Deborah, rather than using some of your bread dough, we think you’ll have better results if you use our recipe for Sourdough Starter and begin from scratch. While you might be be able to coax life into your bread dough, the results will be more unpredictable than if you use our tried and tested recipe. Good luck! Kye@KAF

  2. Bonnie Goller

    Like Jeffetx above, I live in a hot climate with no ac. 84 degrees in my kitchen right now, with the fans going. I’m on my second starter, the first one went great guns–on the third day it overflowed a 4-cup glass carafe and then it quit. I tried everything to revive it (fed it with wheat flour, etc.), but the most it would ever do is bubble a little bit–no expansion at all after that first rise. I think it overheated and killed most of the yeastie beasties. I’m now on day 3 of starter #2. It doubled this morning about 4 hours after the feeding, so I put it in the fridge. My question: should I bring it out of the fridge and “warm it up a bit” before I give it its nightime feeding? Thanks! Love this site!

    1. Susan Reid, post author

      Bonnie, you can feed it “cold” with room temperature water and flour; give it a couple of hours on the counter until it gets moving, then put it back in the fridge before it decides to take over your kitchen again!!! Susan

    2. The Baker's Hotline

      Hi Bonnie, the fridge always slows down the activity of your starter. If it’s still in the early stages, we recommend leaving it at room temperature (for at least five days) to ensure it builds up a healthy foundation of wild yeast and friendly bacteria. Once you pass this stage, you can store it in the fridge between feedings. You can take it out of the fridge, discard, add fresh flour and water, and then let it rest at room temperature for 4-6 hours (at least) if possible before putting it back in the fridge. This will help the starter “digest” its recent feeding before being put back to sleep. Kye@KAF

  3. Val in Cincinnati

    Under “ripe and ready to go” you say, “It’s doubled in volume, and shows signs of just beginning to sag under its own weight.” What signs tell us that it’s beginning to sag under its own weight?

    1. The Baker's Hotline

      Val, look for a slight dip in the top surface of the starter. You might even see residue on the sides of the container that shows it’s risen high and now is starting to sink. Kye@KAF

  4. Nanette

    Just received my KA starter and have fed it twice. The booklet does not mention anything about non-clorinated water being necessary. I’m hoping I haven’t killed it as MaryJane mentioned is possible in her Mar 23 posting re chlorinated water. Seemed fine after first feeding, will see how the second goes. If it is affected, will it just need more time to mature? For future reference, do you know if the use of a Brita filter will do the trick?

    Also how can you tell if your starter has been sitting too long and needs another feeding before you can use it to bake?


    1. The Baker's Hotline

      Congrats on your new arrival, Nanette! We don’t usually bring up the issue of chlorinated water unless there’s a problem growing your starter. If you suspect that your tap water may be highly chlorinated, then you may want to consider switching over to bottled water, but we wouldn’t worry too much about it if your starter seems to behaving as it should. Brita filters do claim to reduce the taste and odor of chlorine in waters, so you could give that a try as well, though really there’s no need to worry at this point. As to your second question, the exact amount of time your starter takes to become fully active will vary based on a number of factors, including the strength of the starter and the ambient temp and humidity, but often it takes around 4-8 hours. You’ll know it’s ready when, as Susan describes here, it has “doubled in volume, and shows signs of just beginning to sag under its own weight”. When it passes its peak level of activity, it will start to fall again, and you’ll often notice more bubbles just at the surface, rather than throughout the mixture. For an even more detailed, visual walk-through of the process of building up your starter, please visit our Sourdough Baking Guide and for more info on feeding and maintaining your starter, please visit this companion blog article. Hope this helps and happy baking! Mollie@KAF

  5. Sara

    I’ve been baking with sourdough for about twelve years, and I’ve never been totally satisfied with my results. Using additional yeast, I can get beautiful breads with tight crumb and satisfying flavor, but I’ve never been able to get that good old holey, chewy sourdough with the crackling crust. Until today. I’ve spent the last two weeks reading everything PJ and Susan have written here on sourdough, and last night, I brought it all together, did a little stress-relief in the form of kneading, and this morning, we had the single best pair of loaves ever baked by human hands. A couple keys: I did purchase a new KAF starter, and I did use it. It’s interesting how different it smells from the one that started as a KAF starter years ago but has moved with me all up and down the East coast and is, no doubt, very different now from where it started. I did also bake in my great-great-grandmother’s dutch oven (which is how I bake my hearth bread) at 520 to get that amazing crust. It worked, even in my very leaky, inconsistent oven. And I did an overnight bench rise in the fridge. But I think one of the biggest things is that I looked at the photos Susan posted of when a starter is really ripe and ready to use, and I didn’t rush it. Anyway, thank you PJ! Thank you, Susan! Yum!!!

    1. MaryJane Robbins

      Congratulations Sara! While we provided the inspiration and some helpful tips, you deserve all the credit for those stellar loaves. Huzzah for you! ~ MJ

  6. Trudy Haines

    How critical is the water source? Can tap water be used or does it have to be filtered? Is bottled water the equivalent to filtered?

    1. MaryJane Robbins

      The water can make a big difference in how well your starter thrives. If there is chlorine in the water, it will kill off your yeast (darn anti-bacterials!) Conversely, if you have minerals in the water it can be a boon to your starter. So, if you know your water is treated try using filtered or bottled water. No need for distilled, just a jug o’ water from the store. ~ MJ

    1. The Baker's Hotline

      Carlos, we ref to that liquid as the “hooch;” it’s the alcohol that’s formed as a by-product of fermentation. You can stir it back in to make your starter a bit more tangy. Kye@KAF

  7. Kira Zurick

    Hello! I was given some starter, and it sat in the fridge for about 5 weeks, unfed. I fed it last week, and it’s doing beautifully! Made 2 batches of bread already! Since I’m keeping it in the fridge, is the following recommended? Remove what I need from the starter jar (putting the rest back into the fridge), feed what I took out, allow it to rise, and use that for my recipe. All the while, keeping the rest in the fridge, feeding it once a week. That way, I decrease the amount of starter naturally, and by the end of the week, have 4oz left to feed, so that I don’t need to throw any out. Does that sound feasible long term? Also, after feeding and standing at room temp before refrigerating, is there a minimum amount of time that I should wait before using the refreshed starter? Overnight? 2 days? Thank you for your guidance on my new adventure!

  8. Craig

    I just received my sourdough starter and fed it the first time. The volume is about 1 1/2 cups water and 2 cups flour. I’ve waited 12 hours and the starter is very bubbly.

    The last sentence of Step 1 reads: “Stir the starter and measure out about 4 ounces (about 1/2 cup).”

    Step 2 reads “Mix in 1/2 cup water and 4 ounces (1 scant)n cup flour. Stir well….”

    My question: am I mixing the 1/2 cup water and 4 ounces of Step 2 into the remaining starter or into the 4 ounces that were measured out? I suspect it’s the latter but want to confirm. Thanks!

    1. The Baker's Hotline

      You’re correct, Craig, though at this point in time, 4 oz is probably just about half of your starter, so there would also be 4 oz remaining. Think of it this way, you want the weight of your seed starter to be equal to the weight of the flour and the weight of the water you feed it with–so 4 oz, 4 oz and 4 oz. Mollie@KAF

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