Adding sourdough to a recipe: when it works, how to do it

“I really hate throwing away some of my sourdough starter when I feed it. Isn’t there something else I can do with it, instead of just ditching it?”

Absolutely. Adding sourdough to a recipe is simpler than you might think – so long as you choose the right recipe, and understand how to do it.

First off, let’s get past the romance of sourdough starter – its history, the way it bubbles and grows, its “geographic” range of flavors – and get down to basics. Sourdough starter is equal parts (by weight) flour and water/alcohol, with a bit of organic acids, friendly bacteria, and yeast thrown in.

Why alcohol? Because as the starter ferments, yeast gives off tiny bits of alcohol (in addition to those flavorful organic acids).

Adding Sourdough to a Recipe via @kingarthurflour

Over the course of time, your starter will gradually become slightly more liquid, due to the addition of this alcohol. That dark liquid you see in the photo above is alcohol sitting atop a starter that hasn’t been fed in a couple of weeks.

However, despite this little bit of alcohol, you can continue to think of your starter as equal parts liquid/flour, by weight.

Adding Sourdough to a Recipe via @kingarthurflour

I’ve just fed my starter (left); on the right is my discard, which measures a scant 1 cup (7 ounces).

What can I do with discard starter?

First, you can use it in any of our online recipes calling for unfed starter.

Beyond that, think of recipes in your own repertoire using flour and water. Or flour and another liquid, like milk or coffee or juice.

And by liquid, I mean liquid that doesn’t contribute additional attributes to the baked good’s texture, e.g., vegetable oil, which is mainly fat; or honey, which is mainly sugar. Don’t substitute sourdough starter for liquid sweeteners or liquid fats.

Adding sourdough to a recipe for cake.

Let’s try this unfed starter in one of my favorite cake recipes, King Arthur Flour’s Original Cake Pan Cake – which happens to be our 225th anniversary Recipe of the Centuries.

Adding Sourdough to a Recipe via @kingarthurflour

The recipe calls for 6 1/4 ounces flour and 8 ounces cold water, so it’s a good recipe to use.

I have 7 ounces of “discard” starter (a scant 1 cup). That’s 3 1/2 ounces each water and flour.

So I’ll add that 7 ounces of starter to the recipe; and reduce the amount of flour and water in the recipe by 3 1/2 ounces each: meaning in addition to the starter, I’ll use 2 3/4 ounces flour and 4 1/2 ounces water.

Stay with me here; if you don’t regularly bake with a scale you might feel a little foggy right now, but this is simple arithmetic.

Adding Sourdough to a Recipe via @kingarthurflour

I mix everything together. See the discard starter plopped on top?

Adding Sourdough to a Recipe via @kingarthurflour


Adding Sourdough to a Recipe via @kingarthurflour

The edges of the cake are just barely pulling away from the sides of the pan – that means the cake is fully baked.

Adding Sourdough to a Recipe via @kingarthurflour

I pour a simple icing on top…

Adding Sourdough to a Recipe via @kingarthurflour

…and there you have it, Cake Pan Cake made with discarded sourdough starter.

Adding sourdough to a recipe for yeast bread.

Now let’s try this same process in one of my favorite bread recipes, English Muffin Toasting Bread. While you can substitute unfed starter in yeast bread, I like to give my bread a little extra oomph by subbing fed starter instead.

Adding Sourdough to a Recipe via @kingarthurflour

Here’s my fed starter, fully ripened and ready to go. (For you sourdough newbies, “ripened” means fed and bubbly.)

The English Muffin Toasting Bread recipe calls for 3 cups (12 3/4 ounces) flour, 1/4 cup (2 ounces) water, and 1 cup (8 ounces) milk.

I’m using 8 ounces of ripened sourdough starter. So that means I need to reduce the flour by 4 ounces (to 8 3/4 ounces); and reduce the liquid by 4 ounces by eliminating the water (2 ounces), as well as 2 ounces of the milk.

Adding Sourdough to a Recipe via @kingarthurflour

The batter looks the same as it usually does (left). It rises nicely (center). And bakes up beautifully (right).

Adding Sourdough to a Recipe via @kingarthurflour

The finished loaf slices nicely.

And the taste? It’s not sour, but rather seems richer compared to my usual toasting bread. It’s as though the starter simply enhances the bread’s natural wheat/milk/butter flavor.

Adding sourdough to all kinds of recipes.

Using sourdough starter, either fed or unfed, is possible in a wide range of recipes – so long as the recipe includes sufficient water/flour for you to substitute your starter.

A cookie recipe wouldn’t work well; cookie recipes generally don’t include significant amounts of water or milk. But muffins, biscuits, pancakes, scones… all of those usually include enough liquid for the substitution to work.

One thing to keep in mind: when you’re substituting sourdough starter in a recipe calling for milk, you’ll lose something: milk fat and milk solids, which add flavor and enhance texture. You may be willing to make the tradeoff, but it’s useful to manage your expectations ahead of time.

So, now that you understand the simple process of adding sourdough to a recipe – go forth and bake!

A special note to Madelene, Beth, and Nadine from California’s Bay Area, who recently sent me a lovely present. Ladies, THANK YOU! I’m so touched. Hope you don’t mind the “public display” here, but this is the only way I know to get in touch with you. Sending you all kinds of good baking karma…

PJ Hamel

PJ Hamel grew up in New England, graduated from Brown University, and was a Maine journalist before joining King Arthur Flour in 1990. PJ bakes and writes from her home on Cape Cod, where she enjoys beach-walking, her husband, two dogs, and really good food!


    1. The Baker's Hotline

      Ashley, if you’re using unfed starter, we’d leave the amount of yeast alone, as you won’t get much extra rise from starter that isn’t ripe, just the nice sourdough flavor. Happy baking! Kat@KAF

  1. Tanya

    Any suggestions when subbing in veggie purees for some liquid in sourdough baking? I keep seeing such gorgeous colors so loaves that use purple potatoes/carrots or sweet potato. I wonder about ratios?

    1. The Baker's Hotline

      Hi Tanya! This isn’t something we’ve played with, but we did find a recipe shared on The Fresh Loaf website for a purple potato sourdough bread recipe to give you some ideas. It also includes blue cornmeal so it’s bound to be pretty! Annabelle@KAF

  2. sylvie

    The English Muffin Toasting Bread recipe calls for 3 cups (12 3/4 ounces) flour, 1/4 cup (2 ounces) water, and 1 cup (8 ounces) milk.

    You say I’m using 8 ounces of ripened sourdough starter.
    I am wondering what made you choose to use 8 ounces of sourdough starter.

    I want to make a bread that asks for 15.75 ounces flour. I don’t know how much
    starter to use?

    1. The Baker's Hotline

      Hi there, Sylvie! We chose to use 8 ounces of starter because that is about 1 cup which is a good round number to work with. When first introducing starter to a recipe we’d suggest sticking with the 8 ounces (1 cup) and then working from there. If you’d like to try the recipe the recipe with a little more, you’ll want to keep in mind the amount of liquid called for — it should still be a sufficient amount so that your dough comes together nicely. Happy baking! Morgan@KAF

  3. M Bridgewater

    Hello, I’ve recently started my second ever sourdough starter and have questions. When extracting a measurement of starter, is a dry measuring cup used or liquid measuring cup? I never know and alternate between the two. Also, is starter supposed to be some what solid, or gooey? Mine seems like the equivalent of gravy, or cream of soup, and seems more liquidity after it is fed. Is it okay to feed the starter 1/2, or less than what is removed? I have about 2.5-3 cups of starter, which seems excessive, but, better to have more than run low. Just want to make sure I’m not adding more than is needed when feeding the starter. Thank you, ~m

    1. The Baker's Hotline

      Hi, M! To make everything about 100 times simpler, we recommend measuring everything with a scale. That way, you’ll know that you’re feeding your starter with an equal amount of water and flour by weight for that 1:1:1 ratio.
      The starter consistency you’re describing sounds right. It tends to wafer from thick pancake batter to a cold gravy.
      Sourdough starter is considered a liquid. When it’s time to feed it, you always want to feed one part of starter with one part water and one part flour, all equal by weight. If the starter is fed with portions of flour and water that are less than that of the starter, it won’t die, but it won’t be sour and it’ll have trouble rising.
      If you have any other questions, our free and friendly Baker’s Hotline is available at 855-371-BAKE (2253) or through chat and email on our website so always feel free to reach out. Annabelle@KAF

  4. Jeanie

    Oh No, what happened to my bread! I made Sourdough bread from my ripe starter this morning. I put it in my Kitchen Aid mixer with the dough hook and ran it for about 10 minutes, the dough had made a ball. I followed the recipe, let it rise in an oiled bowl until it was about 1 inch over the pan. The problem came when I uncovered the pan to bake…the dough started falling and spilled over the sides. I baked it, it spilled a little more all over the oven. I finished baking it for the time called for. When I took it out of the oven the top was nice and brown but the sides didn’t brown at all. Did I not knead it enough or have I missed something? Thank you

    1. The Baker's Hotline

      Hi Jeanie, it sounds like there might have been a mismatch between the pan size and the amount of dough the recipe called for. If you’re using a standard loaf pan (about 8 1/2″ by 4 1/2″), then the recipe should call for 3 to 4 cups of flour. If it’s more than that, you might consider scaling it back or using a bigger pan. The other possibility is that the dough fermented too quickly and was left to rise for too long, which happens often during the warm summer months. You can try using cool water when making your dough to help slow down how quickly it expands. This should result in a sturdier structure as well as more complex flavor: bonus! We hope this helps, and feel free to reach out to our Baker’s Hotline if you’d like to troubleshoot further: 855-371-BAKE(2253). Kye@KAF

  5. Sharon Gooch

    Hi! I REALLY want to make sourdough doughnuts- any thoughts? Should I use a yeast doughnut recipe & add my starter as above? A biga? I didn’t see any mention of excluding the yeast in a recipe you’re adding starter to. Do you have recipes for sour dough doughnuts?? Thank you for your help!

    1. The Baker's Hotline

      A sourdough doughnut recipe, how interesting! This might be a little tricky, but you’re able to give it a shot. We’d recommend starting with this recipe for Yeast-Raised Doughnuts here. Add in 1 cup of fed sourdough starter and reduce the flour by 4 ounces and the milk by 4 ounces. (Use about 2 cups of flour and 1/2 cup of milk in the recipe.) You can try reducing the yeast or leaving it out all together if your starter is healthy and strong. You’ll need to extend both the first and second rise times notably in order to allow the wild yeast to proof the dough. We hope you’ll feel encouraged to share your results with us. Good luck! Kye@KAF

  6. Mary

    Hi! Are there any flavors that do not pair well with sourdough? I have seen mainly chocolate, coconut, carrot and spice cake pairing with sourdough. I would like to know your insights as to (when choosing a recipe to adapt to sourdough) what flavorings will work well with sourdough and which ones not.
    I don’t want to end up with lets say… lemon cake sourdough which is just not palatable because lemon and sourdough doesn’t go together.
    Thanks, Great post!!!!!

    1. The Baker's Hotline

      Hi Mary, we’re hesitant to say the sky’s the limit, but heck, we’ll say it: The sky’s the limit when it comes to adding sourdough to recipes! If you come up with a flavor combination that sounds good to your taste buds, it’s likely that you’ll like the final results given a few key points. Be sure to use discard that’s relatively fresh. If the discard has been sitting in the fridge for multiple weeks without being fed, it’ll probably have a “funky” taste that won’t pair well with anything. Also consider the quantity of discard you’re adding to a recipe. If you’re unsure if the flavors will jibe, like in the lemon cake example you gave, consider using 1/2 cup of starter instead of a full cup. We’ve come up with recipes that pair sourdough with figs and oranges, maple and walnuts, apricots and oats, dates and cranberries, and even pumpkin spice! Kye@KAF

  7. Nancy Martin

    Thank you so much for your response. I will definitely check out the guide you suggest. I love learning from the experts 🙂

  8. Nancy Martin

    I have wondered about using leftover starter also and appreciate this post. I do have a question, as I am have not used sourdough for long; however have baked bread for many years. As this says “unfed” sourdough, why is this, rather than feeding the “leftover” starter to make other items or putting it back in the fridge, fed? I am not familiar with the science of sourdough as far as fed or unfed. Since most recipes call for “fed”, i am a little confused. Thank you so much for this information! And thank you for all your amazing recipes and products, along with actually addressing questions or concerns.

    1. The Baker's Hotline

      Hi Nancy, the answer to many of your questions can be found in our Sourdough Baking Guide. In short, every time you’re ready to use your sourdough starter, it needs to be “fed” beforehand (a.k.a. fresh water and flour are added); when it’s straight from the fridge or has been on the counter inactive for a few days it’s considered “unfed.” Feeding your starter ensures that it will be active and ready to make the dough rise. Before the fresh water and flour can be added, part of the starter must be discarded or thrown out. This step is key to growing a successful sourdough starter; it helps keep the balance of the pH within a healthy level so that wild yeast and bacteria can thrive. It doesn’t have to be a wasteful step, either. You can give away the discard to a friend to start their own culture, or you can use it in recipes like these. To get a better idea of what a fed or “ripe” starter looks like, check out this article here. Between the article and the guide, we hope you’ll get a better understanding of how to feed your sourdough starter and why it’s so important. Kye@KAF

  9. H


    I have a very stiff starter (fed at 67% hydration) and I am having trouble calculating what I would use in a recipe. For example, lets say a recipe calls for 500g of flour, and I have 220 grams of my stiff excess starter I want to throw in. How exactly do I figure out how much flour and how much water is in that 220 grams of starter? Do I just multiply 220 by .67? I am so lost.

    1. The Baker's Hotline

      Hi H! In order to figure out the flour/water content of your 220 grams of starter at 67% hydration, you have to remember that the 67% relates to the weight of the flour, which is always considered 100%. This means that for each 100 units of flour in any given amount of your starter, there are 67 units of water. In order to figure out the weight of each ingredient you need to come up with the conversion factor, which is the total weight of the ingredients divided by the total of the percentages, or 220 divided by 167 = approximately 1.32 (always round up). If you then multiply this factor by the percentage of each ingredient, it will give you 132 grams of flour, and 88.44 grams of water = 220.44 grams (close enough). This is a bit complicated, I know. Now that you’ve figured out the weight of the flour and water in your starter, you can subtract this amount of flour and water from the recipe. Keep in mind, however, that you need to be a little careful about how much sourdough starter you add to a recipe because this can make a big difference in the acidity of the dough and how quickly it ferments. Barb@KAF

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