Note: Don’t let sourdough versus commercial yeast stop you from trying a recipe. As long as you’re willing to pay attention to the dough and ignore the recipe’s rising-time recommendations, you can make a yeast recipe with sourdough starter and vice versa.

I’m going to use the term “starter” throughout these instructions to refer to mature levain/starter.

Please read all the way to the end if your dough is enriched, meaning it contains butter or oil, sweetener e.g. sugar, honey, and/or eggs.

To convert a recipe and retain the same hydration, you just need to figure out how much flour and water are in the starter, and move that flour and water into different ingredient categories. Unless otherwise indicated, most starter is half flour and half water by weight, but if the starter is dryer or wetter, you would simply divide the starter differently.

Of course, this is just a basic approach to get you going. Once you mix up a dough, you might decide you want to add more flour or water. I believe the safest course of action is to make a recipe at least once as it’s written to get a sense of dough-feel at different stages, but you can dive right into a converted recipe if you prefer.

Sourdough -> Yeast: Divide the starter grams in half, and add those amounts to the flour and water weights.

Here’s an example of this conversion using our Savory Babka recipe:

Sourdough

275g flour

200g sourdough starter

125g milk

75g plain yogurt

5g salt

Yeast Conversion

200g sourdough starter divided in half is 100g flour and 100g water

375g flour (275g original flour + 100g flour from the starter)

100g water (+ 100g water from the starter)

200g sourdough starter

125g milk

75g plain yogurt

5g salt

yeast amount is up to you*

*Use as little as ¼ tsp yeast to get a long rise similar to using sourdough. This will create more complex flavors and give you some hands-off gluten development. Or use 1 to 2 ¼ tsp yeast for the dough to double in 1 to 3 hours. (2 ¼ tsp yeast is equal to one packet.)

Yeast -> Sourdough: Decide how many grams of starter you want to use. 10-20% of the total flour weight is fairly typical. Then divide that starter amount in half, into flour and water weights, and subtract those amounts from the flour and water listed in the recipe.

Here’s an example of this conversion using our Bagel recipe:

Yeast

838g flour

486g water

17g salt

5g instant yeast

5g diastatic barley malt powder

Sourdough Conversion

I’m choosing 30% starter because this is a dry dough and I want a lot of leavening power:

838g flour x 0.30 = 250g starter

250 / 2 = 125g flour and 125g water

713g flour (= 838 – 125)

361g water (= 486 – 125)

250g sourdough starter

17g salt

5g (~1 ½ tsp) instant yeast

5g (~1 ½ tsp) diastatic barley malt powder

If you don’t have a scale, make the recipe conversions in grams until you have your final ingredient list to avoid confusion, and then convert the grams to volume. Using the savory babka as an example again:

Divide the flour grams by 130 to get cups. 1 cup flour = 130g

375/130 = 2.88 cups flour

Divide the water and milk grams by 237 to get the cups. 1 cup water/milk = 237g

100/237 = 0.42 cups water

125/237 = 0.53 cups milk

You can find more weight-to-volume ingredient conversions online.

Enriched Dough

When converting between yeast and sourdough in a dough that contains extra fat, protein, and sugar aka an enriched dough like brioche or cinnamon rolls, you should be working with a special, sweet stiff sourdough starter build. Enriched dough rises better, tastes less sour, and turns a nice golden color when baked (Maillard reaction) if the sourdough starter has been fed flour and sugar and less water. The adding and subtracting described above applies here too, only you’ll also account for sugar, and the water and flour amounts won’t be the same. To learn more about the whys and hows of sweet stiff starter, check out this article: Sourdough Starter and Maillard Reaction in Enriched Doughs.