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. Rocky

    Hi Chef…
    I have noticed some sourdough sites are different in measuring ingredients,,,Some say if your starting with 100 grams of stater feed with 50 grams water and 50 grams of flour…While others say for 100 grams of starter feed 100 grams water and 100 grams flour…Which is correct…Thank you…Rock

    1. The Baker's Hotline

      Rocky, there are many successful ways to create and maintain a sourdough starter, so both ways are perfectly correct. In this case the starter that is fed a smaller amount of flour and water will likely ferment more quickly, because it has a smaller meal to consume. In both cases the starter is being fed equal parts flour and water, so the consistency will be about the same. Our starter calls for equal parts starter, water and flour. Barb@KAF

  2. Becky C

    I am about to make my first loaf. Kind of scary! I have a “spare” in the fridge, just in case.

    I have been contemplating it for over a year…now, to jump in. Practice, practice, right?

    Also, isn’t spelt flour gluten free, or lower in gluten?

    1. The Baker's Hotline

      Spelt is an ancient strain of wheat – it’s high in protein and has a nutty, complex flavor that’s sweeter and lighter than whole wheat. Substitute it for whole wheat flour in any recipe – its gluten is not as strong, so it’s best to combine with all-purpose or bread flour if you’re baking to give your breads enough structure. Happy Baking! Irene@KAF

  3. Sunnye Tiedemann

    I am really frustrated. My sourdough doesn’t taste sour. It’s just like plain, old regular bread. I want to make the kind of tangy sourdough I experienced in San Francisco. How can I get that?

    1. Susan Reid, post author

      Sunnye, the most common misconception about how to get sour tasting bread is that it has to do with the starter. It has more to do with allowing the finished dough produce more acid for more tang. The best way to do that is to give your finished dough a long, slow rise before baking. Try shaping your next loaf and putting it in the fridge overnight before baking the next morning. You’ll be surprised what a difference it makes. Susan

    1. Susan Reid, post author

      Yes, Paula, metal pans are fine. If you’re concerned you can always line them with some parchment. Susan

    1. Susan Reid, post author

      Gabby, the importance of discarding starter is twofold. You need to have equal amounts of old starter and new food, to keep the acid level consistent. If you add new food to twice as much old starter, the acid from the yeast and bacteria will be twice as high. The best thing to do is use the discard to make a recipe which doesn’t require ripe starter (we have a number of these on the website), or use your discard as the beginning of some pizza dough. If you want healthy, ripe starter that is capable of lifting your bread, it needs to be vigorous and active, with the best conditions for growth. Susan

  4. Deb


    I would like to see more recipes that exclude packaged yeast. The recipes on Kinf Arthur’s site seem to always include them. I’m making bread and pizza dough with my starter but would like more recipes. Thank you!!

    1. Susan Reid, post author

      Deb, you can make any recipe that calls for starter without yeast. If the starter is ripe, just leave the yeast out and allow more time for rising. Susan

    1. Susan Reid, post author

      Irene, that photo is meant to capture what many people who have neglected jars of starter in their refrigerators looks like. If you had a jar of starter sitting there for a month without feeding it, it would look pretty much the same. Many people believe that something that looks so (relatively) unappealing must either be a) dead or b) somehow beyond redemption. Neither are true. With regular care and feeding, that starter became the happy, bubbly one you see at the end of the post. Susan

  5. Jon

    How long will an inactive starter last if kept refrigerated? I’ve heard they can last quite a while, because the fermentation creates alcohol which helps preserve it? Can you just feed it and bring it back to life then?

    1. Susan Reid, post author

      Hi, Jon. I have sucessfully revived starter that has had no attention whatsoever for 4 months. There’s a good week of feeding and discarding involved to get it back in shape, but it can be done! Susan

  6. Darcy

    Oh you just saved my sourdough beginnings! I haven’t been able to figure out why my starter and loaves have been so thin! Of all the recipes I’ve read, I never realized it was equal WEIGHTS for the water and flour and have been doing equal volumes!!! Oi! THANK YOU!

    1. Susan Reid, post author

      Excellent, Darcy, we’ll keep coming at the subject from all angles, looking to provide those light bulb moments!

  7. grace kratovil

    Either I am too short on time, or just plain lazy. I’ve had a starter going for a little over a year. It is kept in the frig. When I bake bread, I take it out, pour about half in the mixing bowl, add the rest of the ingredients, plus some potatoes, seeds, mashed beans, etc, minus a little of the called for yeast, mix and bake. (Like my precise measurements?) Bread rises fast, not very sour-my husband’s preference. It is then fed only one time per week. Sourdough starter seems completely forgiving, right?

    1. Susan Reid, post author

      Grace, that is SO true! I have often done something very similar (particularly for pizza dough). Yet, I bet your bread stays fresher longer and doesn’t go moldy, either. Sourdough is great stuff. Susan

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