Sourdough Bread Calculator — Perfect Ratios Every Time
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How Sourdough Bread Calculation Works
Sourdough bread calculation uses baker's percentages -- a universal system where every ingredient is expressed as a percentage of total flour weight, with flour always representing 100%. According to the Bread Bakers Guild of America, baker's percentages are the professional standard used in bakeries worldwide because they allow any recipe to be scaled up or down while maintaining consistent ratios. This calculator determines the exact amounts of flour, water, sourdough starter, and salt needed for your target loaf weight, hydration level, and starter percentage.
The critical distinction in sourdough calculation is that the starter itself contains flour and water. A typical sourdough starter maintained at 100% hydration is equal parts flour and water by weight. When you add 200g of starter to a recipe, you are actually adding 100g of flour and 100g of water. This calculator accounts for these contributions, ensuring your final dough reaches the intended hydration level. Without this adjustment, a recipe calling for 75% hydration would actually be wetter than intended. The Tartine Bakery method, popularized by Chad Robertson, uses 20% starter at 75% hydration -- a benchmark that produces reliably excellent bread with an open crumb. Our spice conversion calculator can help with herb additions to flavored loaves.
The Baker's Percentage Formula
The formula starts with total dough weight and works backward: Total Flour = Total Dough Weight / (1 + Hydration% + Starter% + Salt%). Then: Water = Flour x Hydration%, Starter = Flour x Starter%, Salt = Flour x Salt%.
Worked example: One 800g loaf, 75% hydration, 20% starter, 2% salt. Total flour = 800 / (1 + 0.75 + 0.20 + 0.02) = 800 / 1.97 = 406g flour. Water = 406 x 0.75 = 305g. Starter = 406 x 0.20 = 81g. Salt = 406 x 0.02 = 8g. Total = 406 + 305 + 81 + 8 = 800g.
Key Terms
Hydration: The ratio of water to flour by weight. At 65% hydration, 1000g flour requires 650g water. Higher hydration produces more open crumb structure but is harder to handle. Typical range: 65-85%.
Sourdough Starter: A culture of wild yeast and lactic acid bacteria maintained by regular feedings of flour and water. A mature, active starter roughly doubles in volume 4-8 hours after feeding. Most starters are maintained at 100% hydration (equal parts flour and water).
Bulk Fermentation: The first rise after mixing, typically 4-12 hours depending on temperature and starter percentage. During bulk fermentation, the dough develops flavor, strength, and gas structure through a series of stretch-and-folds.
Autolyse: A rest period (20-60 minutes) after mixing flour and water but before adding starter and salt. This allows flour to fully hydrate and gluten to begin forming, resulting in a more extensible dough with less kneading required.
Sourdough Hydration Reference Table
| Hydration | Dough Character | Best For | Skill Level |
|---|---|---|---|
| 60-65% | Stiff, easy to shape | Bagels, pretzels, sandwich loaves | Beginner |
| 68-72% | Moderate, manageable | Classic country loaf, pan bread | Beginner |
| 73-77% | Slightly sticky, good crumb | Artisan round loaves, batards | Intermediate |
| 78-82% | Very sticky, open crumb | Ciabatta, focaccia, open crumb boules | Advanced |
| 83-90% | Extremely wet, large holes | Ciabatta, pan-baked focaccia | Expert |
Practical Examples
Example 1 -- Beginner's first loaf (70% hydration): One 750g loaf, 20% starter, 2% salt. Flour = 750 / 1.92 = 391g. Water = 274g. Starter = 78g. Salt = 8g. This produces a manageable dough that is easy to shape. Use bread flour (12-13% protein) for best results. Bulk ferment 6-8 hours at room temperature (72-76F).
Example 2 -- Tartine-style open crumb (78% hydration): One 900g loaf, 20% starter, 2% salt. Flour = 900 / 2.00 = 450g. Water = 351g. Starter = 90g. Salt = 9g. Use a blend of 90% bread flour and 10% whole wheat for flavor. Perform 4-6 stretch-and-folds during the first 2 hours of bulk fermentation, then let it rise undisturbed for 3-4 more hours.
Example 3 -- Batch baking (4 loaves): Four 800g loaves, 75% hydration, 15% starter, 2% salt. Total dough = 3200g. Flour = 3200 / 1.92 = 1667g. Water = 1250g. Starter = 250g. Salt = 33g. A longer, cooler fermentation (10-14 hours at 65F) with lower starter percentage develops more complex sour flavor. Use our meal prep calculator for batch planning.
Tips and Strategies
- Feed your starter 4-12 hours before baking. The starter should be at peak activity (doubled in size, domed on top, passing the float test) when you mix your dough for the best rise and flavor.
- Use weight, not volume. Baking is chemistry -- accurate measurements matter. A $15-$25 kitchen scale accurate to 1g is the single most important sourdough tool.
- Control temperature. Fermentation speed doubles with every 15F (8C) increase. At 72F, bulk fermentation takes 6-8 hours. At 82F, it may only take 3-4 hours. At 65F, expect 10-14 hours.
- Start with lower hydration. Master 70% hydration before increasing. Each 5% increase in hydration requires significantly more skill in handling, shaping, and timing.
- Cold retard for flavor. After shaping, place the dough in the refrigerator (38-42F) for 12-48 hours. This slows yeast activity while lactic acid bacteria continue producing sour flavor, resulting in a more complex taste and better oven spring.
Frequently Asked Questions
What hydration should I use for sourdough bread?
For beginners, 65-70% hydration produces a stiffer dough that is easy to handle and shape, yielding a tight, uniform crumb suitable for sandwiches. A 75% hydration is the most popular all-around choice, producing a moderately open crumb with good flavor and manageable handling. At 80-85%, the dough becomes very sticky and difficult to shape without experience, but yields the large, irregular holes prized in artisan bakeries. Start at 70-72% and increase by 2-3% per bake as your skills improve. The flour type also matters -- high-protein bread flour (12-14% protein) handles higher hydration better than all-purpose flour (10-12%).
How much sourdough starter should I use?
The standard range is 15-25% of total flour weight. Using less starter (10-15%) results in a longer fermentation time (8-14 hours at room temperature) which develops more complex sour flavors and better dough strength through extended gluten development. Using more starter (25-35%) accelerates fermentation (3-5 hours) but may reduce sourness and oven spring because the dough becomes fully fermented before developing optimal structure. The Tartine method popularized 20% starter as a versatile default. Adjust based on your schedule -- less starter for overnight ferments, more starter when you need bread quickly.
What is baker's percentage and why does it matter?
Baker's percentage is a formula notation system where every ingredient is expressed as a percentage of total flour weight, with flour always defined as 100%. For example, a recipe with 1000g flour, 750g water, 200g starter, and 20g salt is written as 100% flour, 75% hydration, 20% starter, 2% salt. This system makes scaling recipes effortless -- whether you are making one loaf or one hundred, the ratios stay the same. It also allows bakers to instantly compare recipes: a 75% hydration recipe from one source is directly comparable to a 75% hydration recipe from another, regardless of the total dough weight.
How do I know when bulk fermentation is done?
Bulk fermentation is complete when the dough has increased in volume by 50-75% (not doubled), feels airy and jiggly when you move the container, shows visible bubbles on the surface and sides, and holds a dome shape when a portion is scooped with a wet hand. Over-fermenting (more than doubling) produces a slack dough that deflates during shaping and yields a flat, dense loaf. Under-fermenting produces a tight crumb with poor oven spring. At 72-76F (22-24C), bulk fermentation typically takes 6-8 hours with 20% starter. Using a clear container with volume markings makes tracking expansion much easier.
Why does my sourdough taste too sour or not sour enough?
Sourness is controlled by fermentation time, temperature, and starter management. For more sour bread: use a longer, cooler bulk fermentation (12-16 hours at 65F), retard shaped loaves in the fridge for 24-48 hours, use whole grain flour (whole wheat or rye feed the acid-producing bacteria), and use a stiff starter (60% hydration). For milder flavor: use shorter fermentation times (4-6 hours at 78F), minimal cold retard, white flour only, and a liquid starter (100%+ hydration). The type of acid matters too -- acetic acid (vinegar-like) develops in cooler, drier conditions, while lactic acid (yogurt-like mildness) dominates in warmer, wetter conditions.
Can I use this calculator for sourdough discard recipes?
This calculator is designed for active, fed starter in bread recipes where leavening is expected. Sourdough discard recipes (pancakes, waffles, crackers, pizza dough) use unfed starter primarily for flavor rather than leavening, and often include commercial yeast or baking soda as the rising agent. For discard recipes, the starter amount is less precise and does not need to be calculated as a percentage of flour. A typical discard recipe uses 100-200g of discard and adjusts flour and liquid to achieve the desired consistency. The calorie calculator can help track the nutritional content of your sourdough bakes.