Sourdough baking is all about ratios — specifically the baker's percentage system where everything is measured relative to flour weight. A standard sourdough loaf uses 100% flour, 70-75% water (hydration), 20% starter, and 2% salt. Higher hydration creates a more open crumb with larger holes, while lower hydration produces a tighter, more sandwich-friendly texture. This calculator converts your desired loaf size and hydration level into exact ingredient weights in grams. Precision matters in sourdough — even 5% hydration difference dramatically changes how the dough handles and the final crumb structure.
Sourdough Bread Calculator
Sourdough Recipe
Sourdough Hydration Guide
How hydration affects dough handling and crumb structure.
| Hydration | Dough Feel | Crumb | Best For |
|---|---|---|---|
| 65-68% | Stiff, easy to shape | Tight, even crumb | Sandwich loaves, bagels |
| 70-73% | Moderate, manageable | Medium crumb, some holes | All-purpose loaves |
| 74-78% | Tacky, needs bench rest | Open crumb, good holes | Country loaves, batards |
| 79-83% | Wet, sticky, advanced | Very open, large holes | Ciabatta-style, high-hydration boules |
| 84-90% | Very wet, pour-like | Extremely open, irregular | Focaccia, ciabatta, pan breads |
How to Use This Calculator
- Enter your desired total dough weight — 900g makes a standard boule, 450g makes a small loaf
- Set your target hydration percentage — 65% for beginners, 70-75% for intermediate, 80%+ for advanced bakers
- Adjust starter percentage — 15-20% is standard, higher for faster fermentation in warm environments
- Set salt percentage — 2% is standard, range of 1.8-2.2% based on preference
- View exact weights for flour, water, starter, and salt in grams
How It Works
Sourdough recipes use baker's percentages, but the starter itself contains both flour and water. This calculator accounts for that, ensuring your final dough has the correct hydration.
The basic rule:
- Starter contributes flour and water — these are subtracted from totals
- A 100% hydration starter is 50% flour, 50% water by weight
- Final dough flour = total flour − flour in starter; final water = total water − water in starter
This calculator also includes a levain build section showing you how much starter, flour, and water to combine the night before your bake. Use a kitchen scale for accuracy — sourdough baking is all about precision.
Tips & Considerations
- Your starter's hydration affects the final dough hydration. A 100% hydration starter (equal parts flour and water) is assumed by most recipes. If yours differs, this calculator adjusts accordingly.
- Whole wheat and rye flours absorb more water than white bread flour. Add 5-10% more hydration when using whole grain flours.
- Temperature controls fermentation speed more than anything else. At 78°F, bulk fermentation takes 4-6 hours. At 65°F, it takes 8-12 hours. Cold retard in the fridge runs 12-48 hours.
- Weigh everything in grams, not cups. A cup of flour can vary from 120g to 160g depending on how it is scooped, which makes a 33% difference in your recipe.
Frequently Asked Questions
What does starter hydration mean?
Starter hydration is the ratio of water to flour in your starter, expressed as a percentage. A 100% hydration starter has equal parts flour and water by weight (e.g., 50g flour + 50g water = 100g of 100% hydration starter). Most sourdough starters are maintained at 100% hydration.
How much starter should I use?
Most recipes call for 15-25% starter relative to total flour. Using 20% is a good default. More starter (25-30%) means faster fermentation. Less starter (10-15%) means slower, longer fermentation with more complex flavor. Adjust based on your schedule and ambient temperature.
Why does the calculator subtract flour and water from the starter?
Your starter is a mixture of flour and water. If you add 200g of 100% hydration starter, you're adding 100g flour and 100g water. This flour and water count toward your total recipe amounts, so you need to subtract them from the flour and water you add separately.
What hydration should I use for sourdough bread?
For beginners, 70-75% hydration is manageable and produces great bread. Experienced bakers often use 78-85% for a more open crumb. Lower hydration (65-70%) is easier to shape and good for sandwich loaves. Higher hydration requires stronger shaping technique.
What is a levain build?
A levain (or leaven) is a portion of starter that you feed the night before baking to ensure it's at peak activity. You take a small amount of your starter, feed it with fresh flour and water, and let it ferment 8-12 hours. The calculator shows how much to build.
How do I know when my starter is ready to use?
Your starter is ready when it has doubled in size, has a domed top, and passes the float test (a small spoonful floats in water). This typically takes 4-8 hours after feeding at room temperature. The timing depends on your starter's strength and ambient temperature.