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. Laura

    Hi Susan,

    My mother gave me some of her starter which is fed weekly with potato flakes and sugar. It looks like it was originally called an Amish Friendship starter. Can I use this starter in the KAF sourdough recipes? If not, can I convert this starter by starting to feed it flour instead?


    1. Susan Reid, post author

      Hi, Laura. Your Amish starter is designed for sweet breads, and isn’t at all what we’re asking for when we write a sourdough bread recipe. You are much better served just mixing up some flour and water (see our Sourdough Baking Guide for more complete info). Susan

  2. Ted

    Um…what’s the weight of the remaining sourdough in the jar, after I’ve discarded half and before feeding with 4ounces (by weight) of each flour and water? Thank you!

    1. Susan Reid, post author

      Hi, Ted. You’re looking to have 4 ounces of starter to feed, and 4 more ounces each of flour and water for a total of 12 ounces when you’re done. Susan

  3. Vivian Kokkinos

    BTW I have been diagnosed with diabetes and I felt guilty making sourdough bread. So I researched on google if sourdough bread is good for you. To my delightful surprise, it turns out that research has shown that sourdough bread made in the traditional way without any commercial yeast and with a long rising method, not only does not give you a glucose spike but it also has a carry over effect keeping your glucose in check for your next meal as well. Have anyone else done any research on this?

  4. Jeffetx

    I swear I’m gonna get off my duff and try SD…, how about my wonnerful ol’ S. Texas home, lotsa doors and windows – no AC. Do I assume I am going to be doing some experimention, running back and forth from the fridg to counter top?
    (We have had several running days of what we call triple didget weather, no end in sight!!).
    I refuse to feel I am in an impossible situation for SD…..I can’t imagine Tx mother’s of old didn’t bake with it! (in fact many times in the summer I doubt they had any choice LOL)

    1. Susan Reid, post author

      No reason you can’t get sourdough to work, even in the Lone Star State. Just don’t count on 12 hour intervals between feedings, or if you need to stay on that schedule, leave the starter on the counter for 4 hours, or until you see it doubling in size. Then give it a time out in the refrigerator. Also, when feeding, start with cold water to keep things from running away on you. Susan

  5. Vivian Kokkinos

    I started baking sourdough about 20 years ago using Nancy Silverton’s book and actually made my own starter following her instructions. Her sourdough starter is much more liquid (or hydrated is how bakers put it). What is the advantage of using a stiffer starter if any? Actually, feeding the starter as per your instructions is easier as you use equal weight of all the ingredients for the feedings.

    1. The Baker's Hotline

      Hi Vivian,
      You ask a great question! The starter shown in this post here is considered a liquid starter. You may have used a starter in the past that was even more liquidy (more than 100% hydration), which tends to ferment more quickly. A starter that is made up of equal amounts water and flour by weight is easy to incorporate into recipes as well as feed. It ferments at just the right rate for us; it needs to be fed about once a week.

      A truly stiff starter has different benefits. To read more about the advantages of baking with a stiff starter, check out our blogger Barb’s post on Artisan Sourdough Bread. These kinds of starters tend to have more sourness and are more easily identified as ripe. I hope this helps. Happy sourdough baking! Kye@KAF

  6. Shirley Twining

    I have difficulty understanding why it is that we have to discard half when we are rejuvenating the sour dough. Why not just “do” the whole thing, adding more four and water? Seems to work for me!

    1. Susan Reid, post author

      Hi, Shirley. If you’re planning on making a lot of bread, there’s no reason not to feed the whole amount of starter. Say your stored amount is roughly 1 1/2 cups in volume, around 12 ounces. To keep the pH in balance, you’d need to feed that whole amount of starter with 12 ounces of water and 12 ounces of flour. Now you’re going to have, in total, between 4 1/2 and 5 cups of starter. That’s a LOT of starter. Which means in order not to waste it, you need to make a double batch of bread, 2 batches of waffles, and maybe some sourdough muffins. Susan

  7. Avis Barbera

    When a recipe calls for 2 cups of fed starter, that amount consumes all of my starter with none left over to feed and live again for another loaf. Am I supposed to double the amount of starter that I make by using the discard to work up another batch? If so, do I use the same ratio, i.e.: 8 oz starter, 8 oz water and 8 oz flour?

    1. The Baker's Hotline

      Avis, you’re on the right track! When you need to build your starter, it’s fine to retain more starter and feed it an equal amount of flour and water. Say you need two cups of starter (16 ounces) for a recipe, for the last feeding before using your starter in your recipe you could save 7 ounces of starter and feed it 7 ounces of water and 7 ounces of starter; this will give you 21 ounces of starter–enough to use 16 in your recipe and have 5 ounces left over to feed and maintain. By keeping the ratio of ingredients the same in your starter it will stay more consistent in its rising and falling, but it also works to simply double the amount of flour and water you normally feed your starter. In this case your starter will rise more slowly because it has more food to consume. Barb@KAF

  8. Erica S

    I’ve just read through all the comments and learned so much! I’m still new to starter, so after I finishing reviving it from its 3 week fast (shame), I think I’ll try resting the finished loaf overnight in the fridge. I really want to get that “San Francisco sour” tang. I work during the day–do you think I could rest the loaf for up to 20 hrs or so in the fridge before baking? (i.e. Overnight plus through the workday…)

    1. MaryJane Robbins

      HI Erica,
      You may not want to start with such a long rise right off the bat. Try an overnight rise on a weekend, and get used to the process. Then you can try other timetables as you gain experience. ~ MJ

  9. Robert Gottlieb

    This is a question. Can yeast from wild grapes be incorporated into an existing sourdough starter, e.g. by adding grapes when the starter is fed and then removing them?

    1. Susan Reid, post author

      Hi, Robert. What you’re describing is a cage match between the strains of yeast. There are hundreds of them, and depending on how well established the strain in your start is, inoculating the starter a second time may have no discernable effect or it may change the starter. It depends entirely on which strain of yeast wins out. Susan

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