Sourdough Calculator

Bakers use percentages called Baker's Percentages, where total flour is always set to 100%, and all other ingredients are measured relative to that total weight. To find the starter weight, the calculator multiplies your main flour weight by your desired starter percentage divided by 100. Starter itself is a blend of flour and water; for example, a 100% hydration starter is split evenly by weight between flour and water. The tool breaks down your total flour (TFlour) by combining your main recipe flour with the flour contributed by your starter (SFlour). Similarly, total water (TWater) accounts for the hydration liquid you add plus the water already locked inside your active starter. Salt is typically calculated as 2% of the total flour weight, ensuring your crumb and crust develop optimal flavor and strength.

Let us walk through a practical batch using 500 grams of main recipe flour, a 20% inoculation (starter percentage), and a starter with 100% hydration. First, calculate the starter amount: 500 g × 0.20 = 100 grams of starter. Because your starter has 100% hydration, it is half flour and half water; therefore, it contributes 50 grams of flour (SFlour) and 50 grams of water (SWater) to your final dough. Your total flour (TFlour) becomes 500 g + 50 g = 550 grams. If you are targeting an overall dough hydration of 75%, your total water needed is based on your total flour, yielding roughly 412 grams of total water. Subtracting the 50 grams already coming from your starter means you will add 362 grams of fresh water (Water) to your mixing bowl. Finally, adding 2% salt based on total flour gives you 11 grams of salt, resulting in a cohesive, perfectly proportioned dough.

Always weigh your ingredients in grams using a digital kitchen scale rather than using volume measurements like cups, as flour density varies wildly. Keep track of your starter's hydration level—if it has been fed with equal parts flour and water by weight, its hydration is 100%. Adjust your water additions slightly depending on the protein content and absorption capacity of your specific brand of flour.