Sourdough Calculator
Free Sourdough Calculator for desserts & baking recipes. Enter amounts to convert, scale, or adjust ingredients precisely.
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Total flour weight is derived by dividing the desired total dough weight by the sum of all baker's percentages (1 for flour + hydration decimal + salt decimal). The starter's flour and water contributions are then subtracted from the totals to determine added flour and added water amounts. Starter flour fraction = 1/(1 + starter hydration).
Last reviewed: December 2025
Worked Examples
Example 1: Standard Sourdough Loaf (1 kg dough)
Example 2: High-Hydration Ciabatta Sourdough
Background & Theory
The Sourdough Calculator applies the following established principles and formulas. Cooking and food preparation involve a surprisingly rich set of mathematical relationships that govern texture, flavour, nutrition, and safety. Recipe scaling is perhaps the most immediately practical: to adjust a recipe serving 4 to serve 10, every ingredient quantity is multiplied by the ratio 10/4 = 2.5. This works straightforwardly for most ingredients, but leavening agents, salt, and strong spices often need more conservative scaling because their effects are not strictly linear at larger volumes. Baker's percentage is a professional notation system in which every ingredient is expressed as a percentage of total flour weight. If a dough uses 1000 g flour and 650 g water, the hydration is 65%. This system makes formulas portable across batch sizes and allows bakers to adjust hydration, enrichment, or fermentation characteristics with precision. Temperature conversion between Fahrenheit and Celsius (°C = (°F − 32) × 5/9) is essential when following recipes written for a different regional audience. The Maillard reaction, responsible for browning and the development of complex flavour compounds in bread crusts, roasted meats, and caramelised vegetables, occurs most rapidly above approximately 140°C (285°F) and accelerates with temperature. Yeast activity is highly temperature-sensitive: active dry yeast proofs optimally between 38°C and 43°C (100°F–110°F), and temperatures above 60°C are lethal to yeast cells. Volume-to-weight conversions in cooking rely on ingredient density, which varies significantly: a cup of all-purpose flour weighs approximately 120–130 g, while a cup of honey weighs around 340 g. Relying on volume for dense or variable-density ingredients introduces meaningful measurement error. The pH of a batter determines how leavening agents behave: baking soda (sodium bicarbonate) requires an acid such as buttermilk or vinegar to activate, while baking powder contains its own acidic component and works in neutral batters. Nutritional density calculations, expressed as kilocalories per 100 g, allow comparison of foods on a consistent basis, supporting dietary planning and labelling compliance.
History
The history behind the Sourdough Calculator traces back through the following developments. The culinary arts have ancient roots spanning every human civilisation, but the formalisation of cooking as a measurable, teachable discipline emerged gradually over centuries. Ancient Egyptian, Greek, and Roman texts contain references to food preparation, and medieval European monasteries developed sophisticated brewing and baking traditions that implicitly encoded ratios and techniques passed through apprenticeship. The most transformative figure in modern professional cooking was Auguste Escoffier, whose systematisation of classical French cuisine in the late 19th and early 20th centuries created a codified brigade system and a catalogue of standardised preparations that became the foundation of professional culinary training worldwide. His work, particularly Le Guide Culinaire published in 1903, treated cooking as a discipline with repeatable, transmissible formulas rather than purely intuitive craft. Home economics emerged as a formal academic discipline in the 19th century, partly in response to industrialisation and urbanisation. Figures such as Catharine Beecher and later Ellen Richards in the United States worked to apply scientific principles to domestic cooking and nutrition, eventually institutionalising the subject in schools and universities. Standardised recipe development became central to the food industry in the 20th century as mass food manufacturing required consistent, scalable formulas. The USDA introduced its first food pyramid in 1992 as a public health tool to communicate recommended nutritional ratios to a general audience, though the model has been revised multiple times since. MyPlate replaced the pyramid in 2011 with a simpler visual. Molecular gastronomy, pioneered in the 1990s by chefs such as Ferran Adria at elBulli and Heston Blumenthal at The Fat Duck, brought laboratory techniques and rigorous scientific analysis to high-end cooking, exploring the chemistry of gels, foams, emulsifications, and temperature-controlled preparations. Food calorie labelling laws, mandated on packaged foods in the United States since 1990 under the Nutrition Labeling and Education Act, formalised the expectation that consumers would engage with nutritional arithmetic as part of daily food choices.
Frequently Asked Questions
Formula
Flour = Total Dough / (1 + Hydration + Salt%)
Total flour weight is derived by dividing the desired total dough weight by the sum of all baker's percentages (1 for flour + hydration decimal + salt decimal). The starter's flour and water contributions are then subtracted from the totals to determine added flour and added water amounts. Starter flour fraction = 1/(1 + starter hydration).
Worked Examples
Example 1: Standard Sourdough Loaf (1 kg dough)
Problem: Calculate ingredients for a 1000g dough at 75% hydration, 20% starter (100% hydration), and 2% salt.
Solution: Total flour = 1000 / (1 + 0.75 + 0.02) = 1000 / 1.77 = 564.97g\nStarter = 20% x 565.0 = 113.0g (56.5g flour + 56.5g water)\nAdded flour = 565.0 - 56.5 = 508.5g\nTotal water = 75% x 565.0 = 423.7g\nAdded water = 423.7 - 56.5 = 367.3g\nSalt = 2% x 565.0 = 11.3g\nTotal: 508.5 + 367.3 + 113.0 + 11.3 = 1000.0g
Result: Flour: 508.5g | Water: 367.3g | Starter: 113.0g | Salt: 11.3g
Example 2: High-Hydration Ciabatta Sourdough
Problem: Calculate ingredients for 750g dough at 85% hydration, 15% starter (100% hydration), 1.8% salt.
Solution: Total flour = 750 / (1 + 0.85 + 0.018) = 750 / 1.868 = 401.5g\nStarter = 15% x 401.5 = 60.2g (30.1g flour + 30.1g water)\nAdded flour = 401.5 - 30.1 = 371.4g\nTotal water = 85% x 401.5 = 341.3g\nAdded water = 341.3 - 30.1 = 311.2g\nSalt = 1.8% x 401.5 = 7.2g
Result: Flour: 371.4g | Water: 311.2g | Starter: 60.2g | Salt: 7.2g
Frequently Asked Questions
What is baker's percentage and why is it used for sourdough recipes?
Baker's percentage (also called baker's math) is a system where every ingredient is expressed as a percentage of the total flour weight, with flour always being 100%. For example, 75% hydration means the water weight is 75% of the flour weight, and 20% starter means the starter weighs 20% of the flour. This system is universally used in professional baking because it makes recipes infinitely scalable — you can make one loaf or one hundred using the same percentages. It also makes it easy to compare recipes and understand dough characteristics at a glance. A 65% hydration dough will be noticeably stiffer than an 80% hydration dough, regardless of total batch size. Baker's percentage accounts for the flour and water contributed by the sourdough starter itself.
How does hydration percentage affect sourdough bread?
Hydration dramatically affects the texture, crumb structure, and handling properties of sourdough bread. Lower hydration doughs (60-65%) produce tighter, more uniform crumbs suitable for sandwich bread and are easier to shape. Medium hydration (68-75%) creates a balance of open crumb and workability, ideal for most artisan loaves. High hydration (78-85%) yields the large, irregular holes characteristic of ciabatta and high-hydration country loaves but requires advanced shaping skills. Very high hydration (85%+) produces focaccia-style breads. Higher hydration also extends fermentation time slightly and increases oven spring. Beginners should start at 70-72% and gradually increase as they develop handling skills, since wet doughs are more challenging to shape and score.
What is the ideal sourdough starter percentage and how does it affect fermentation?
The starter percentage controls fermentation speed and flavor development. A lower percentage (10-15%) creates a longer, slower fermentation that develops more complex sour flavors through increased lactic and acetic acid production. A higher percentage (25-30%) speeds up fermentation significantly, producing a milder, sweeter bread. The standard range of 15-20% balances flavor development with practical timing, typically allowing a 4-6 hour bulk fermentation at room temperature. In cold weather, increasing to 25% compensates for slower yeast activity. In hot weather, reducing to 10-12% prevents over-fermentation. The starter should be used at its peak activity — typically 4-8 hours after feeding when it has doubled in volume and shows a domed top with bubbles throughout.
How much salt should I use in sourdough bread and does it affect fermentation?
The standard salt percentage for sourdough bread is 1.8-2.2% of total flour weight, with 2% being the most common recommendation. Salt serves multiple critical functions: it strengthens gluten structure, controls fermentation rate, enhances flavor, and improves crust color through better caramelization. Reducing salt below 1.5% produces bland bread that ferments too quickly and has a weaker crumb structure. Exceeding 2.5% can inhibit yeast activity excessively and make bread taste overly salty. Fine sea salt or kosher salt dissolves most easily into dough. Many bakers add salt during the autolyse or after initial mixing, as adding it too early can tighten the gluten prematurely and inhibit initial hydration. Salt should never be mixed directly with the starter, as high salt concentration can kill the wild yeast.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Does Sourdough Calculator work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy