🍞 Sourdough Starter Calculator
Feed a sourdough starter at a ratio of starter : flour : water — so 30 g of starter at 1:2:2 needs 60 g flour and 60 g water.
Ratio is starter : flour : water = 1 : 2 : 2. Equal flour and water = 100% hydration.
60 g
Flour to add
60 g
Water to add
150 g
Total starter after feed
100%
Hydration
A feed ratio of 1:2:2 means for every 1 g of starter you keep, add 2 g flour and 2 g water — a common maintenance feed. Higher ratios (1:5:5, 1:10:10) dilute the starter more, so it takes longer to peak but can go longer between feeds; lower ratios peak faster. Discard the rest before feeding, or use it in discard recipes. 🔒 In your browser.
How the sourdough starter calculator works
Enter how much starter you're keeping and your feed ratio (parts flour and water per part starter). The calculator multiplies the starter weight by each ratio to give the flour and water to add, the total starter after feeding, and the hydration (water ÷ flour × 100). Equal flour and water gives a 100% hydration starter, the most common kind.
A higher feed ratio (like 1:5:5 or 1:10:10) dilutes the mature starter more, so it takes longer to rise and peak but can wait longer before it's hungry again — useful for feeding once a day or overnight. A lower ratio (1:1:1) peaks quickly, good when you need active starter fast. Discard the excess before feeding to keep the amount manageable, or save it for discard recipes. Weigh ingredients in grams for accuracy.
Frequently asked questions
How do I feed my sourdough starter?
Keep a little starter, then add flour and water in your chosen ratio. At 1:2:2, keep 30 g and add 60 g flour and 60 g water. The calculator gives the exact amounts for any starter weight and ratio.
What does a 1:2:2 ratio mean?
It's parts of starter : flour : water. For each part of starter you keep, you add two parts flour and two parts water. So 20 g starter becomes 20 g + 40 g flour + 40 g water = 100 g fed starter.
What ratio should I feed at?
For regular use, 1:1:1 peaks fast (a few hours); 1:2:2 to 1:5:5 rise more slowly and suit once-a-day feeding; 1:10:10 can stretch overnight or longer. Warmer kitchens ferment faster, so use a higher ratio in summer.
What hydration should my starter be?
100% (equal flour and water by weight) is the standard, giving a thick-batter consistency. Stiffer starters (lower hydration, like 50–60%) ferment more slowly and keep longer; this tool shows the hydration for whatever ratio you enter.