Sourdough Calculator
Sourdough baking is all about ratios. This calculator takes your desired flour weight and hydration level and works out exactly how much water, starter, and salt you need. It accounts for the flour and water already in your starter so your final dough hydration is accurate.
Baker's percentages express every ingredient as a percentage of the total flour weight. If you use 500 g of flour at 75% hydration, you need 375 g of total water. At 20% starter, you need 100 g of starter. But here is the catch: your starter already contains flour and water. A 100% hydration starter is half flour and half water by weight, so 100 g of starter adds 50 g of flour and 50 g of water to your dough.
This calculator subtracts the flour and water in the starter from the totals, so the amounts you see for "flour" and "water" are what you actually add to the mixing bowl alongside the starter. That way your true dough hydration matches your target.
Starter percentage controls fermentation speed. More starter (25-30%) means a faster rise, which is handy in cold kitchens. Less starter (10-15%) gives a slower, more flavorful ferment. Most recipes land around 20%. Salt is typically 1.8 to 2.2% of flour. It controls fermentation, strengthens gluten, and adds flavor. Going below 1.5% makes fermentation harder to control; going above 2.5% can taste noticeably salty.