Sourdough Bread Calculator
Sourdough Bread Calculator
Sourdough bread baking is both an art and a science. Unlike bread made with commercial yeast, sourdough relies on a fermented starter — a living culture of naturally occurring yeasts and bacteria — to leaven the dough and develop its characteristic tangy flavor. This introduces an extra variable into the baker's formula: the starter itself contains both flour and water at a specific hydration ratio, and both must be accounted for when calculating the final ingredient quantities.
The Sourdough Bread Calculator handles this complexity automatically. You specify your desired loaf size, hydration percentage, salt percentage, inoculation rate (the amount of starter relative to total flour), and the hydration of your starter. The calculator then determines the exact amounts of flour and water to add, subtracting the contributions already present in the starter.
This approach is based on baker's percentages, the standard method professional bakers use to scale recipes. In baker's percentages, the total flour weight is always 100%, and all other ingredients are expressed as a percentage of that flour weight [foodgeek-bakers-pct]. A 75% hydration dough means the water weight is 75% of the flour weight. A 20% inoculation means the starter weight is 20% of the total flour weight.
The critical insight that many home bakers overlook is that the starter contributes both flour and water to the dough. A 100% hydration starter (liquid levain) is equal parts flour and water by weight. If you add 200g of this starter, you are adding 100g of flour and 100g of water. The calculator subtracts these from the total required, ensuring your final dough has exactly the hydration and ingredient ratios you intend.
Enter the number of loaves you want to bake and the desired dough weight per loaf. Adjust the target hydration (the water-to-flour ratio), salt percentage, and inoculation rate. Select your starter type — liquid levain (100% hydration), medium (80%), or stiff starter (60%). Choose your flour type for reference.
The calculator displays the total flour, total water, starter weight, flour and water contributed by the starter, added flour and water, salt, and total dough weight.
Example 1: Standard Country Loaf
You want one 900g loaf at 75% hydration with 20% liquid levain (100% hydration) and 2% salt.
- Number of loaves: 1
- Dough weight per loaf: 900 g
- Hydration: 75%
- Salt: 2%
- Inoculation: 20%
- Starter hydration: 100% (liquid levain)
Results:
- Total flour: 456.9 g
- Total water: 342.7 g
- Starter: 91.4 g (45.7 g flour + 45.7 g water)
- Added flour: 411.2 g
- Added water: 297.0 g
- Salt: 9.1 g
- Total dough: 900 g
Mix 411 g flour with 297 g water, add 91 g starter and 9 g salt. Bulk ferment for 4-5 hours at room temperature, shape, proof, and bake.
Example 2: High Hydration with Stiff Starter
You want a single 950g loaf at 80% hydration with 15% stiff starter (60% hydration) and 2.2% salt.
- Number of loaves: 1
- Dough weight per loaf: 950 g
- Hydration: 80%
- Salt: 2.2%
- Inoculation: 15%
- Starter hydration: 60%
The calculator accounts for the stiffer starter having less water per gram, requiring more added water to reach the target hydration. The result shows added flour and added water after subtracting starter contributions.
Example 3: Edge Cases
Very high hydration (100%): A ciabatta-style dough at 100% hydration requires very wet handling. The calculator handles this but the result will have high added water. Be aware that such doughs require stretch-and-fold techniques rather than kneading.
Low inoculation (5%): A very small amount of starter extends the bulk fermentation significantly — expect 12-18 hours at room temperature. The calculator shows the starter weight, which will seem small, but the fermentation can produce excellent flavor.
Whole wheat vs white flour: Whole wheat flour absorbs more water than white flour. If switching flour type, adjust hydration up by 5-10% to maintain the same dough consistency.
Sourdough ingredient calculations use baker's percentages, adjusted for starter contributions [perfect-loaf-bakers].
Let:
- W = Total dough weight
- h = Target hydration (%)
- s = Salt percentage (%)
- i = Inoculation percentage (%)
- s_h = Starter hydration (%)
For a 100% hydration starter (s_h = 100):
Manual Step-by-Step
Using Example 1 (900g loaf, 75% hydration, 20% inoculation, 2% salt, 100% starter):
Step 1: Find total flour: 900 ÷ (1 + 0.75 + 0.02 + 0.20) = 900 ÷ 1.97 = 456.9 g
Step 2: Starter weight: 456.9 × 0.20 = 91.4 g
Step 3: Flour from starter: 91.4 ÷ 2 = 45.7 g (at 100% hydration, starter is half flour, half water)
Step 4: Water from starter: 91.4 - 45.7 = 45.7 g
Step 5: Added flour: 456.9 - 45.7 = 411.2 g
Step 6: Target total water: 456.9 × 0.75 = 342.7 g. Added water: 342.7 - 45.7 = 297.0 g
Step 7: Salt: 456.9 × 0.02 = 9.1 g
Hydration and Crumb Characteristics
| Hydration | Dough Character | Crumb | Typical Breads |
|---|---|---|---|
| 50-55% | Stiff, dry | Dense, tight | Bagels, pretzels |
| 60-65% | Firm, easy to handle | Moderate crumb | Sandwich loaves |
| 70-75% | Slightly sticky, manageable | Open, airy | Country boule |
| 75-80% | Wet, needs folds | Large irregular holes | Artisan ciabatta |
| 80-85% | Very sticky, challenging | Very open | High-hydration sourdough |
| 85-100% | Batter-like, advanced technique | Extreme open | Pan de cristal |
Starter Hydration Reference
| Starter Type | Hydration | Consistency | Feed Ratio | Fermentation Speed |
|---|---|---|---|---|
| Liquid levain | 100% | Batter-like | 1:5:5 (1:2:2) | Fast (4-6 hr peak) |
| Medium | 80% | Thick batter | 1:3:3 | Moderate (6-8 hr peak) |
| Stiff starter | 60% | Dough-like | 1:2:2 | Slow (8-12 hr peak) |
Common Inoculation Rates and Fermentation Times
| Inoculation | Bulk Ferment (75°F) | Flavor Profile | Best For |
|---|---|---|---|
| 5-10% | 12-18 hours | Very tangy, complex | Cold retard preferment |
| 15-20% | 4-6 hours | Moderate tang | Standard sourdough |
| 25-30% | 2.5-4 hours | Mild, sweet | Quick weekday loaves |
| 35-50% | 1.5-2.5 hours | Very mild | Hybrid sourdough / commercial |
Account for flour type absorption. Whole wheat and rye flours absorb significantly more water than white flour — approximately 5-10% more. If substituting whole wheat for white, increase the target hydration by the same amount to maintain dough consistency. The flour type selector provides guidance but does not auto-adjust hydration.
Match starter inoculation to your schedule. A 20% inoculation with a 100% hydration starter at 75°F bulk ferments in about 4-5 hours (perfect for a same-day bake). Lower inoculation (10%) extends fermentation to 8-10 hours, which develops more complex acidity but requires planning. Higher inoculation (30%) produces a faster, milder rise.
Adjust water temperature for dough temperature. The final dough temperature should be 75-78°F for sourdough. Use warm water (80-90°F) in cold kitchens and cool water (65-70°F) in warm kitchens. A 5°F difference in dough temperature can change bulk fermentation time by 30-45 minutes.
The starter is not 100% active. Even a mature starter at peak ripeness is only about 50-70% leavening power by volume. The calculator assumes an active starter at peak. If using a refrigerated or underfed starter, expect longer fermentation times. Maintain your starter with regular feedings (1:5:5 ratio at 100% hydration) for reliable results.
Use the scrapings method to reduce waste. Instead of discarding excess starter, maintain a small mother culture (30-50g) and build it up only when baking. For a single loaf needing 91g of starter, feed 15g of mother culture with 45g flour and 45g water, wait 6-8 hours, and use the full amount.
When NOT to use this calculator: The calculator assumes a single-dough method with all starter added at the beginning. It does not cover levain builds (multi-stage builds that develop acidity separately), poolish or biga preferments, or recipes that add commercial yeast alongside sourdough.
The calculator provides exact theoretical quantities, but real-world results depend on variables outside the model. Flour absorption varies by brand, protein content, and even the season's harvest. A winter wheat flour from one mill may absorb 3-5% more water than a spring wheat from another.
The starter activity level is assumed to be at peak ripeness. An under-ripe starter (just fed, not yet bubbly) or over-ripe starter (fallen, vinegary) will behave differently. The calculator does not model fermentation activity or predict proofing times — those depend on temperature, starter health, and flour characteristics.
The calculator returns an empty result if the starter's flour or water contribution exceeds the total needed (added flour or water goes negative). This occurs when the inoculation rate is very high relative to the dough weight, or when the starter hydration is very different from the recipe hydration. If this happens, reduce the inoculation rate or adjust the target hydration.
Salt percentages assume fine sea salt or table salt. Coarse kosher salt weighs less per volume (approximately half by volume), but the calculator uses weight. Always weigh salt on a digital scale for accuracy. The standard 1.8-2.2% range is ideal for flavor and gluten structure.
- What is the difference between liquid levain and stiff starter?
- Liquid levain (100% hydration) is equal parts flour and water by weight, producing a batter-like consistency that ferments quickly — typically 4-6 hours to peak at room temperature. Stiff starter (60% hydration) is closer to a firm dough, ferments more slowly (8-12 hours), and produces a milder acidity with more lactic acid relative to acetic acid, resulting in a less tangy flavor.
- Why does my dough not rise even when the calculator says it should?
- Several factors can cause poor rise: the starter may not be at peak ripeness (it should double in volume within 4-8 hours of feeding), the dough temperature may be too cold (below 70°F significantly slows fermentation), or the flour may have low protein content (below 11% protein produces weak gluten). Check starter activity first — a float test (drop a small spoonful of starter in water; if it floats, it is ready) is a reliable indicator.
- Can I use the calculator for whole wheat or rye sourdough?
- Yes, the flour type selector lets you choose the flour blend. However, whole wheat and rye absorb more water than white flour. For best results, increase the target hydration by 5-10% when using significant amounts of whole grain flour. Also note that whole wheat and rye doughs ferment faster due to higher mineral and enzyme content.
- What inoculation rate should I use for a beginner?
- 20% is the most forgiving inoculation rate for beginners. It provides a manageable bulk fermentation of 4-6 hours at room temperature, giving you enough time to perform stretch-and-folds without rushing. Lower rates (10%) require overnight schedules that are harder to monitor. Higher rates (30%+) speed up fermentation but can lead to over-proofing if not watched carefully.
- How do I adjust the recipe for cold proofing?
- For a cold retard (refrigerated final proof of 8-48 hours), reduce the inoculation rate to 10-15% so the bulk fermentation completes before the cold slows everything down. The calculator does not model cold proofing directly, but a lower inoculation rate compensates for the additional fermentation that occurs during the first few hours in the refrigerator before the dough fully cools.
- What does 'hydration' mean in sourdough baking?
- Hydration is the ratio of water to flour in the dough, expressed as a percentage. A 75% hydration dough has 75g of water for every 100g of flour. Higher hydration produces more open crumb and larger holes but makes the dough stickier and harder to handle. The calculator accounts for the water already present in your starter when calculating the total hydration.
- How do I know if my starter is ready to use?
- A mature starter at peak ripeness has doubled or tripled in volume, is domed on top (not collapsed), has a bubbly surface, smells pleasantly sour and yeasty (not like nail polish remover or cheese), and passes the float test. At 100% hydration and 75°F, this typically takes 4-8 hours after feeding, depending on the inoculation ratio used in the feed.
- Do I need to adjust for altitude?
- At high altitude (above 5,000 feet), sourdough fermentation accelerates due to lower atmospheric pressure. Reduce the inoculation rate by 5-10% and monitor bulk fermentation carefully — it may complete 20-30% faster than at sea level. The lower boiling point of water does not affect dough temperature, but the drier air may require a 2-3% increase in hydration.
- Should I use tap water or bottled water for sourdough?
- Chlorinated tap water can inhibit fermentation. If your tap water has a strong chlorine smell, let it sit out for 30-60 minutes before using (chlorine dissipates), or use filtered or bottled water. Avoid distilled water, which lacks the minerals yeast needs. Water with moderate hardness (50-100 ppm TDS) produces the best fermentation.
- What does the 'Starter Hydration' setting do?
- The starter hydration setting tells the calculator how much water is in your starter relative to flour. A 100% hydration starter is half flour, half water. A 60% hydration starter is about 62.5% flour and 37.5% water. The calculator subtracts the correct amounts from the total flour and water needed, ensuring your final dough has exactly the target hydration regardless of starter type.
- Can I freeze sourdough dough for later?
- Yes. Shape the dough after bulk fermentation, then freeze immediately without a warm proof. When ready to bake, thaw in the refrigerator overnight, then proof at room temperature until doubled (typically 3-5 hours). The calculator's quantities work for freeze-and-bake; no formula adjustment is needed, though expect slightly less oven spring.
- Why is there flour from the starter and added flour as separate numbers?
- The separation is important for mixing. You physically add the starter (which contains both flour and water) and then separately add additional flour and water. If you simply added 'total flour' to your mixing bowl, you would double-count the flour already in the starter. The added flour and added water numbers tell you exactly what to put in the bowl beyond the starter.
- [1]The Perfect Loaf. "Baker's Percentages and Sourdough Formula Explained."
- [2]FoodGeek. "Sourdough Starter Hydration and How It Affects Your Bread."
- [3]Bertinet, Richard. Dough: Simple Contemporary Bread. Kyle Books, 2008.
- [4]Forkish, Ken. Flour Water Salt Yeast: The Fundamentals of Artisan Bread and Pizza. Ten Speed Press, 2012.
- [5]Leo, Maurizio. "Sourdough Hydration and Baker's Percentages." The Perfect Loaf.
- [6]López-Alt, J. Kenji. "The Food Lab's Guide to Sourdough Starter." Serious Eats.
- [7]King Arthur Baking Company. "Sourdough Starter Maintenance Guide."
Last updated: June 15, 2026
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