Enter the total levain size you need, pick a feeding ratio, and get the exact starter, flour and water amounts to mix — in grams, kilograms, ounces or pounds.
A sourdough feeding ratio is written as starter : flour : water, by weight. The total parts (add the three numbers together) divide evenly into whatever total levain weight you need — for a 1:2:2 ratio, that's 5 parts, so a 200g levain needs 40g of each "part": 40g starter, 80g flour, 80g water.
The ratio controls how much existing microbial population is diluted into fresh food. A 1:1:1 ratio dilutes the least, so there's more starter relative to food and it ripens fastest — often in 4–8 hours at room temperature. A leaner ratio like 1:5:5 dilutes much further, giving the culture more food to work through, which takes longer (12 hours or more) but produces a milder-tasting, less acidic levain.
This calculator assumes a 100% hydration starter — equal weights of flour and water — which is the most common way home bakers maintain a culture, and why the flour and water amounts always come out equal for a given ratio.
The three numbers are parts of existing starter, flour and water by weight, in that order. A 1:5:5 ratio means for every 1g of starter you keep, you add 5g of flour and 5g of water. Higher numbers mean more dilution and a slower, longer fermentation before the starter is ready to use.
1:1:1 ripens fastest (roughly 4–8 hours at room temperature) and suits a same-day bake or a starter you feed twice a day. 1:2:2 is a common middle ground for once-a-day maintenance. 1:5:5 or leaner ferments slowest (12+ hours), giving a milder, less acidic levain — useful for an overnight build or a starter kept at cooler room temperature.
Yes — a 100% hydration starter, meaning equal parts flour and water by weight, which is the most common way to maintain a starter. If you keep a stiffer starter (a lower percentage of water to flour), you'll need to adjust the flour and water split yourself rather than using the calculator's equal split.
This calculator only tells you the amounts for the portion you're keeping and feeding, not what to do with any starter left over before a feed. Discard can be used directly in pancakes, crackers or flatbreads, or simply thrown away — it doesn't affect the ratio math for the starter you're carrying forward.
