Pick your loaf size, hydration, and starter amount and get exact gram measurements. The flour and water already inside your starter are subtracted from what you add — the detail most recipes silently get wrong.
72–78%: the common artisan open-crumb range.
A 100%-hydration starter is half flour, half water by weight. Add 200 g of it to a recipe and you've added 100 g of flour and 100 g of water. Recipes that quote a hydration percentage without counting this drift several points from their stated hydration — enough to change how the dough handles. This calculator solves the full system so the stated hydration is the real one.
65–70% gives an easy-handling dough and tighter crumb, right for beginners and sandwich loaves. 72–78% is the artisan sweet spot. Above 80% the crumb opens dramatically but the dough demands confident handling and strong flour. Whole wheat and rye absorb more water, so push hydration up 3–5 points per 20% whole grain.
Starter percentage is your throttle. 20% at a warm room temperature might bulk ferment in 4–5 hours; drop to 10% for a slow overnight bulk, or raise it in a cold kitchen. Stiff levains (65% hydration) ferment with milder acidity than liquid starters.
Flour absorption varies by brand, age, and humidity. Mixing with about 95% of the calculated water and adding the rest gradually (bassinage) lets you stop where the dough feels right rather than where the math says.