How to Convert Any Bread Recipe to Sourdough

Here is a scenario I hear about almost every week: someone has a bread recipe they love — maybe it is a family recipe for dinner rolls, a cookbook focaccia, or a sandwich bread they have been making for years — and they want to make it with sourdough instead of commercial yeast. The question is always the same: "Can I just swap in starter for the yeast?"

The short answer is yes. The longer answer is that you need to do a little math and adjust your expectations about timing. But the conversion itself is straightforward, and once you understand the formula, you can convert virtually any yeasted bread recipe to sourdough.

The Basic Conversion Formula

A standard sourdough starter is roughly 50% flour and 50% water by weight (a 100% hydration starter). When you add starter to a recipe, you are adding both flour and water. So you need to reduce the flour and water in the original recipe to compensate.

How Much Starter to Use

A good starting point is to use starter equal to about 20 to 30 percent of the total flour weight. For a recipe that calls for 500g of flour, that means 100 to 150g of starter. More starter means faster fermentation. Less starter means slower fermentation with more flavor development.

Step-by-Step Example

Let us say you have a sandwich bread recipe that calls for:

• 500g all-purpose flour
• 325g water
• 10g salt
• 7g instant yeast
• 30g butter
• 20g sugar

Step 1: Remove the yeast entirely. You will not need it.

Step 2: Decide on your starter amount. Let us use 125g (25% of the flour weight).

Step 3: Subtract from flour and water. 125g of starter contains roughly 62.5g flour and 62.5g water. So your adjusted recipe becomes:

• 437.5g all-purpose flour (500 minus 62.5)
• 262.5g water (325 minus 62.5)
• 125g active sourdough starter
• 10g salt
• 30g butter
• 20g sugar

Everything else — salt, butter, sugar, any other additions — stays the same.

Adjusting the Timeline

The biggest change when converting to sourdough is time. Commercial yeast works fast — most yeasted breads are mixed, risen, and baked within 3 to 4 hours. Sourdough is slower, but that slow fermentation is exactly what gives it better flavor and texture.

Bulk fermentation: Instead of 1 to 2 hours, expect 4 to 8 hours at room temperature, or 8 to 16 hours in the fridge. The dough is ready when it has increased in volume by about 50 to 75 percent and feels airy and jiggly.

Proofing: Final proof will also take longer — typically 2 to 4 hours at room temperature or overnight in the fridge. Use the poke test: press a floured finger about half an inch into the dough. If it springs back slowly and leaves a slight indent, it is ready.

Special Considerations for Enriched Doughs

Recipes with butter, eggs, sugar, or milk need extra attention. Fats and sugars slow down fermentation, so enriched sourdough doughs take longer than lean ones. Here is what to keep in mind:

• Use more starter. For enriched doughs, go closer to 30% of the flour weight to compensate for the slower fermentation.
• Be patient with rising. A sourdough brioche or cinnamon roll dough might take twice as long to proof as its yeasted version. This is normal.
• Cold fermentation is your friend. Enriched doughs benefit enormously from an overnight fridge rest. The cold firms up the butter, making the dough easier to handle, while the slow fermentation builds incredible flavor.

What About the Sour Flavor?

Not every bread needs to taste sour. If you want a mild flavor (better for sandwich bread, dinner rolls, or sweet breads), use your starter at its peak activity — right when it is bubbly and just starting to dome. A young, active starter produces more mild lactic acid rather than sharp acetic acid.

If you want more tang (great for crusty loaves and pizza dough), let the bulk fermentation go longer, or do an extended cold ferment in the fridge. Time and temperature are your flavor controls.

Start with a recipe you know well so you can feel the differences. Once you have done it once or twice, the conversion becomes second nature. And then every bread recipe you find becomes a sourdough recipe waiting to happen.