Sourdough Calculator
Calculate flour, water, starter, and salt for any sourdough loaf using target weight and baker's percentages.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Enter your target dough weight and adjust the baker's percentages to match your recipe. The calculator breaks out both the total flour and water (including what is in the starter) and the amounts you add directly at mixing time. Here is how to use each field:
- Target dough weight. This is the total weight of all ingredients combined. A single standard loaf is typically 800-1000g of dough. For two loaves, use 1600-2000g. The calculator scales everything from this single number.
- Hydration. The ratio of total water to total flour. A 75% hydration dough is a good starting point for most sourdough beginners. Higher hydration (80-85%) creates a more open crumb but is significantly wetter and harder to shape. Lower hydration (65-70%) produces a denser crumb that is easier to handle.
- Starter percentage. How much starter to use as a percentage of total flour. The default 20% is a common amount for an 8-12 hour ambient temperature fermentation. Use 10% for a longer, slower fermentation (overnight). Use 25-30% for a faster rise, especially in cold kitchens.
- Salt percentage. 2% of flour weight is the standard for sourdough. Salt controls fermentation rate and develops gluten. Do not reduce below 1.5% or the dough will be bland and over-ferment quickly.
- Starter hydration. Most home bakers maintain a 100% hydration starter (equal weights of flour and water). If you maintain a stiffer starter (e.g., 80%) or a more liquid one (120%), change this number to get accurate added flour and water calculations.
About Sourdough Baker's Percentages
In sourdough, the starter contributes both flour and water to the final dough. This matters because at 100% hydration, a 180g starter contains 90g of flour and 90g of water. If you add this to your dough without accounting for it, your actual hydration will be different from your target. This calculator automatically subtracts the flour and water inside the starter from the amounts you add directly, so the "Added Flour" and "Added Water" fields tell you exactly what to weigh at mixing time.
Example: For a 900g loaf at 75% hydration with 20% starter (100% hydration), the total flour is approximately 468g, total water 351g, and starter 94g. The starter contains 47g flour and 47g water. So you add 421g flour, 304g water, 94g starter, and 9g salt directly. Total: 421 + 304 + 94 + 9 = 828g. The remaining ~72g comes from fermentation gas lost during baking.
Frequently Asked Questions
What hydration should I use for sourdough bread?
For beginners, 70-75% hydration is the recommended starting range. This produces a moderately open crumb that is workable without being extremely sticky. As you gain experience with shaping and folding, you can increase to 78-82% for a more open crumb. Hydration above 85% requires advanced technique and is best left until you are consistently happy with lower hydration loaves. Note that whole wheat and rye flours absorb more water, so recipes with these flours can often handle higher hydration.
How much starter should I use for sourdough?
The typical range is 10-25% of total flour weight. Use 10% for a long, slow room temperature fermentation (12-18 hours) or a cold overnight proof in the refrigerator. Use 20% for a standard same-day bake with a 4-6 hour bulk fermentation. Use 25-30% if your kitchen is cold or your starter is sluggish. More starter means faster fermentation and a milder flavor. Less starter means slower fermentation and more complex, tangy flavor.
What is starter hydration and does it matter?
Starter hydration is the ratio of water to flour in your starter. A 100% hydration starter is a liquid paste of equal weights of flour and water. Some bakers maintain a stiffer starter at 60-80% hydration, which is thicker and develops a different flavor profile. The hydration of your starter affects the hydration calculation for your final dough, which is why this calculator has a starter hydration field. If you are not sure what your starter hydration is, it is almost certainly 100%.
Why does my sourdough not weigh what the calculator predicts?
The total dough weight before baking should closely match the calculator's target. After baking, sourdough loses roughly 10-15% of its weight as water evaporates during the bake. A 900g pre-bake dough will yield an 750-810g finished loaf. Small discrepancies in pre-bake weight come from flour sticking to your hands or work surface during shaping, which is normal. Weigh your ingredients precisely on a kitchen scale for the most consistent results.