Free Online Calculators
A sourdough calculator helps you scale ingredients, calculate hydration percentages, and balance your starter ratios for consistent, bakery-quality bread at home. Simply enter your desired dough weight or flour amount, set your hydration level (typically 65–80%), and the calculator outputs exact measurements for flour, water, salt, and starter.
Standard loaf: 850-900g
Beginner: 70% | Advanced: 75-80%
Typical: 15-25%
Standard: 100% (equal flour & water)
Standard: 2%
A sourdough calculator is a baking tool available online and as a free resource that takes the guesswork out of sourdough bread making. Instead of doing baker's math by hand, you input your target dough weight, hydration percentage, starter percentage, and salt percentage. The calculator instantly gives you precise gram measurements for every ingredient.
Sourdough baking works on a system called baker's percentages, where every ingredient is expressed as a percentage of the total flour weight. This is different from regular recipe fractions. A sourdough bread calculator makes this system easy to use for beginners and experienced bakers alike.
For example, if your recipe calls for 75% hydration and 20% starter, and you want a 900g loaf, you do not need to calculate this manually. The calculator does it for you in seconds.
Hydration is the ratio of water to flour in your dough, expressed as a percentage. It controls the texture, crumb structure, crust, and difficulty of handling your bread.
A sourdough hydration calculator specifically helps you hit the exact water-to-flour ratio your recipe demands and adjust it for your flour type, climate, or personal preference.
Here is how hydration levels affect your bread:
Dough is firm and easy to shape. Great for beginners. Produces a tighter, chewier crumb. Ideal for sandwich loaves.
The sweet spot for most home bakers. Produces an open crumb with good structure. Still manageable without specialized equipment.
Produces the large, irregular holes you see in artisan-style bread. Sticky and challenging to handle. Requires strong flour with high protein content and good technique.
Reserved for experienced bakers. Extremely slack dough. Produces dramatic open crumb but demands precise fermentation control.
Understanding your hydration target is essential before you mix a single gram of flour. The sourdough hydration calculator removes the calculation burden so you can focus entirely on technique.
Baker's percentages are the language of professional baking. Every ingredient is measured as a percentage of the total flour weight, which is always set at 100%.
Here is a standard sourdough formula in baker's percentages:
If your flour weight is 500g, your formula becomes:
This scales perfectly up or down. If you want a larger batch say for two loaves you simply double the flour and every other ingredient scales automatically.
The challenge is that your starter also contains flour and water. A sourdough bread calculator accounts for this. If your starter is 100% hydration (equal parts flour and water by weight), then 100g of starter contributes 50g of flour and 50g of water to your dough. Your true flour and water amounts shift accordingly.
This is called the true hydration or effective hydration of your dough, and it is nearly impossible to track accurately by mental math across multiple batches. A free sourdough calculator handles this automatically.
Your starter is a living culture of wild yeast and lactic acid bacteria. It has its own hydration level separate from your bread dough and this affects how active it is, how sour your bread tastes, and how your final dough behaves.
A sourdough starter hydration calculator helps you maintain and adjust your starter's consistency.
This is the most common home baker starter. It has a thick pancake batter consistency. Easy to maintain, predictable, and works well in most recipes.
Used in traditional Italian panettone and some French baguette traditions. Less sour, more yeasty. Produces lighter, sweeter bread. Harder to mix but very powerful.
Very active, more sour flavor, pourable consistency. Spreads quickly through dough. Some bakers prefer this for whole wheat loaves.
When you change your starter's hydration, it changes the amount of flour and water it contributes to your final dough. The sourdough starter hydration calculator recalibrates your entire recipe around this shift automatically.
Using a free sourdough calculator is straightforward. Here is the exact process:
Decide how much dough you want to make. A standard 900g loaf needs roughly 850–880g of dough. You can enter either your total desired dough weight or your flour weight as the starting point.
Choose your target hydration. If you are a beginner, start with 70%. If you are working with strong bread flour, you can go up to 75–80%.
Most recipes use 15–25% starter relative to flour. Higher starter percentages speed up fermentation. Lower percentages slow it down, which often deepens flavor.
Tell the calculator whether your starter is 100%, 75%, or another hydration. This allows it to account for the flour and water your starter contributes.
Standard sourdough uses 2% salt. Some bakers go up to 2.2% for a more pronounced flavor. Salt strengthens gluten and slows fermentation, so this is not a variable to guess.
The calculator outputs your exact ingredient weights: total flour, total water, starter, and salt. Some advanced calculators also break down the flour types if you are using a blend of bread flour and whole wheat.
One of the most practical uses of a sourdough bread calculator is scaling. A recipe you found online might make one small loaf. You want to make three large ones. Or you want to divide a restaurant-scale recipe down to a single home loaf.
Scaling by hand introduces errors. You might divide some ingredients correctly but forget that changing the salt ratio changes flavor, or that changing the starter percentage changes fermentation timing.
A sourdough bread calculator scales everything proportionally and simultaneously. You change one number the target dough weight and every ingredient adjusts.
This is especially useful when:
Many bakers also want to know the nutritional content of their bread. A sourdough bread nutrition calculator estimates calories, carbohydrates, protein, and fiber based on your ingredients and serving size.
Sourdough has genuine nutritional advantages over commercial yeast bread:
The long fermentation process breaks down some of the starch and creates organic acids. Studies show sourdough bread raises blood sugar more slowly than conventional bread made with commercial yeast.
Wild fermentation reduces phytic acid in the grain. Phytic acid normally blocks the absorption of minerals like iron, zinc, and magnesium. Sourdough fermentation makes these minerals more bioavailable.
The lactic acid bacteria in sourdough partially break down gluten proteins during fermentation. Many people with mild gluten sensitivity report tolerating sourdough better than other breads. (This is different from celiac disease, which requires strict gluten avoidance.)
While baking kills the live cultures in your starter, the fermentation byproducts organic acids, enzymes, and broken-down starches remain in the bread and support digestive health.
A nutrition calculator uses the gram weights you enter for each ingredient to calculate macros per slice. This is useful for bakers tracking their intake or baking for someone with specific dietary needs.
Water is the most impactful variable in sourdough. Adding water by feel rather than by weight is the number one cause of inconsistent results. A hydration calculator forces you to weigh your water precisely.
Many beginner recipes do not explain that your starter is not a neutral ingredient. If your recipe calls for 500g flour and 375g water, but you also add 100g of 100% hydration starter, your true hydration is higher than 75%. The calculator corrects for this automatically.
Salt is small in volume but critical in function. If you double a recipe but only eyeball the salt, you may end up with a bland loaf or one that ferments so fast it over-proofs. Keeping salt at exactly 2% through a calculator prevents this.
Whole wheat flour absorbs significantly more water than white bread flour. Rye absorbs even more. If you substitute flours without recalculating hydration, your dough will be either too stiff or impossibly wet. A calculator lets you adjust hydration for your actual flour blend.
Some advanced sourdough calculators include adjustments for high altitude or very dry environments, both of which change how your dough hydrates and ferments.
Not all flour behaves the same way. When you use a sourdough calculator, you need to choose your flour type thoughtfully.
The standard choice. High protein content builds strong gluten networks. Handles high hydration well.
Lower protein than bread flour. Works well at 70–72% hydration. Not ideal for very open crumb styles.
Contains the bran and germ. The bran cuts gluten strands and absorbs more water. If you substitute 20% whole wheat into a recipe, increase hydration by 2–4%.
Does not form gluten like wheat flour. Very thirsty. Even a 10% rye addition changes dough behavior significantly. Adds deep, earthy flavor and active fermentation.
Lower gluten strength and very high absorption. Require significantly reduced hydration and gentle handling.
A good sourdough hydration calculator lets you enter your flour blend percentages so it can adjust the water recommendation accordingly.