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. Steve

    I have a few questions:
    I spent a week building a starter but I only fed it once a day instead of twice a day. It turned out sour and bubbly, but I never saw it blow up to the super ripe levels. Is this starter ok, or did I screw it up?

    Second, my goal is to have a fridge starter that I only have to feed on the weekends when I bake. My understanding is I should take the starter out on a Saturday night and feed it, leaving it out on the counter. 8-12 hours later I take the “fed” starter I need for my recipes, then replenish my starter and place it back in the fridge until next weekend. Is this correct?

    Lastly: I love the NYT “no-knead” recipe that calls for 12-18 hours of letting the dough ferment before shaping it. If I wanted to use sour dough starter in this recipe, should it be fed or unfed, considering the long time the dough sits?

    1. The Baker's Hotline

      Hi Steve, it sounds like your starter is fine, but may need a little extra TLC in order to get it working optimally when it comes to offering flavor and rise to your sourdough breads (particularly ones that don’t contain added yeast). I would recommend two or three days of twice a day feedings at room temperature to get it more firmly established before you refrigerate it again. After it has been refrigerated for a week, I would try to give it at least two feedings at room temperature before adding it to a recipe. Here’s one possible routine you could follow for your weekend baking: take your starter out of the refrigerator on Friday night and feed it, feed it again Saturday morning, and then Saturday night will be your final feeding before you bake with it on Sunday morning. You could cut out the Friday night feeding, but keep in mind that the more room temperature feedings you can give it, the more lively and active it will be when it comes time to bake your bread.

      You’re absolutely correct that after you remove the portion of fed starter for your recipe, you’ll want to feed 4 ounces of your remaining starter with 4 ounces of flour and 4 ounces of water, and then allow it to sit out for about an hour or two before returning it to the refrigerator.

      I haven’t tried this type of no knead recipe with sourdough starter, but I would say that the risk is that the dough will become too acidic when left out for that long of a time. When the fermentation goes on too long and the acidity builds, this can cause the proteins in the dough to breakdown. It may work with a very small amount of sourdough starter, but I would probably use fed starter as opposed to unfed starter in this case. Barb@KAF

  2. liz

    NEVER Throw the it away.. before using pour 1 cup into a clean jar with a lid in frig..
    I use the sour dough :
    the dough is very forgiving & smells wonderful as it’s fermenting.
    makes beautiful loaves.

  3. Lu

    I am new to sourdough baking, I fed my first batch this morning. I have read several blog posts. This is exciting, because I have not made a loaf of bread for about 10 years. I am wondering if anyone has used sourdough in cake mixes, or cookie recipes? My mom made the best oatmeal cookies when I was a kid. I do not have her recipe, they were cakey. Your input is appreciated.

  4. John M

    I am new to baking bread and trying to make a sourdough starter into day 9 and it just doesn’t seem to be as active as I would expect. Also should I weigh my ingredients on my scale using fluid oz. or just weight. I have been using fluid oz. 4 of starter 4 of water and 4 of flour twice a day

    1. The Baker's Hotline

      John, frequent feedings are the best way to grow your starter, so stick with it! You can also try using some whole wheat flour for a few feedings to give it a bit more vitamins and minerals to enhance activity. We always recommend measuring your ingredients by weight if you have a scale–use regular ounces by weight rather than fluid ounces. Happy baking! Kye@KAF

  5. Karen west

    When I received my sour dough starter I was out of KA All Purpose flour. I only had All Purpose Bleached and KA Whole Wheat so I fed it the whole wheat. Is that okay or did I ruin my starter?

    1. The Baker's Hotline

      You didn’t ruin your starter Karen, but we’re guessing it’s super active at this point! The extra vitamins and minerals in whole wheat flour often make the starter ferment faster than it otherwise would. We recommend switching to feeding it regularly with our all-purpose flour as soon as you can; you can always use your whole wheat flour in the final dough. (Here’s a great recipe for Whole Wheat Sourdough Bread!) Happy baking! Kye@KAF

  6. Fran

    What would be the difference between using ‘discard’ from an active starter (after it’s been kept at room temperature and fed twice a day for 4 days, so it’s very bubbly and active after 12 hours) and using some of it 8 hours after it’s been fed? I’m confused. Someone told me that using what I discard as I feed would qualify as ‘unfed’ starter, but I made some fantastic bread with it… and I can’t see why 4 hours would make any difference between a ‘fed’ and ‘unfed’ starter.

    1. The Baker's Hotline

      Fran, we generally consider a starter “fed” when it has been fed within the last 4-12 hours. Anything outside of that time frame (in either direction) would be considered “unfed”. If you’re using “fed” starter alongside other leaveners (like commercial yeast, baking powder and/or baking soda), the exact timing matters less, but when you’re using it as the sole leavener in a recipe, catching it at its peak activity level, or when it’s fully ripe, is important (and four hours can make a big difference). Finding your starter’s peak activity level can be tricky, and we hope this post helps to shed a little light. For additional questions and/or clarification, feel free to give our Baker’s Hotline a call at 855-371-BAKE. Mollie@KAF

  7. Susan

    I’ve been playing with sourdough and starter for about 2 weeks now, but I’ve not yet been able to get my starter to be quite that airy, and I’m wondering if elevation might have anything to do with it. Im at around 6,000 ft. It’s stayed out on the counter, but I’ve only been doing once daily feedings. Will increasing the feedings increase the bubbles?

    1. The Baker's Hotline

      Hi Susan, while altitude may speed up the fermentation process a bit, we suspect that the bigger culprit is the frequency of feeding. Once fully developed, one feeding per day should be sufficient, but while building the starter, we recommend feeding every 12 hours. While there are many different ways to build and maintain a sourdough starter, it may help to take a read through our guide. Even if you don’t choose to adopt the method itself, you might pick up some helpful hints. Mollie@KAF

  8. John

    I’m interested in starting a sour dough bread starter that uses flour. I’ve been using one that I started but it uses water sugar potato flakes and yeast. Any guidance on doing this ?

  9. Marty m

    Ok I have been lurking around the site, trying to learn all I could about sourdough before I jumped in. Finally took the plunge and ordered some starter and a crock. Fed it a few times and then made my first batch of bread.
    OMG! It’s great. Now my wife won’t let me out of the kitchen. Thanks for all the great advise. Can’t wait to try more recipes

  10. Mary

    My starter was rising ( day three) until I started feeding it twice a day now it doesn’t, what am I doing wrong ( on day four )

    1. The Baker's Hotline

      Mary, not to worry, you may be doing nothing wrong at all. It’s normal to see ebbs and flows in the activity of your starter as you’re building it, and it may simply take a few more days of twice a day feedings to get to a more active state. It is important to take care to either measure your flour by weight or by using our fluff, sprinkle and level method (as seen here: if measuring by volume. This helps ensure that your starter doesn’t become heavier or “stiffer” than intended. You may also want to try peeking at your starter every couple of hours — while it only needs feeding twice a day, it will more than likely have passed its peak by the time you go to feed it every 12 hrs, so you may simply be missing it when it’s most active. Bottom line, it’s a process that takes a lot of patience, so we hope you’ll stick with it and give our Baker’s Hotline a call at 855-371-BAKE if you don’t see more activity in a few more days. We’ll cross our fingers for you in the meantime. Mollie@KAF

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