Start with the dough you actually have
Write down the added flour, added water, starter weight and starter hydration before changing anything. If a recipe says “500 g flour plus 100 g starter,” the 500 g is added flour. It is not the final flour total. Our default example uses 500 g added flour, 350 g added water and 100 g of 100% starter. The resulting totals are 550 g flour and 400 g water: 72.73% hydration.
Use a target to make a small adjustment
For that same flour and starter, a 75% target requires 412.5 g total water. The starter already supplies 50 g, so you add 362.5 g water. That is 12.5 g more than the starting example. This calculation tells you a quantity; it does not guarantee a particular crumb or fermentation time.
Understand what the starter percentage describes
Starter hydration is its water-to-flour ratio. It is different from how much starter a recipe uses. A feeding ratio also includes seed starter, whose composition matters. Do not enter a feeding ratio such as 1:2:2 into the hydration field; use the resulting starter’s hydration percentage.
Keep your experiments comparable
Record the flour brand and blend, ingredient weights, room conditions, handling and the result. Change a small amount of water while keeping the rest of your process as consistent as practical. If the dough feels different after changing flour, do not assume the calculator is wrong: the formula describes composition, not absorption or strength.
Scale everything together
The scaling mode multiplies each ingredient by the same factor. If your original dough weighs 960 g and you want 1,920 g, every weight doubles. The hydration and salt percentage stay the same. The new weight is mixed dough, not a prediction of baked loaf weight; baking removes moisture.
Make rounding a conscious choice
The calculator keeps precision internally and shows ingredient weights to one decimal place. If your scale reads whole grams, round the displayed ingredients when weighing. Small rounding changes can slightly alter the final percentages. Keep the unrounded calculation in your copied notes when comparing larger batches.