Sourdough starter feeding calculator
A feeding ratio is starter to flour to water by weight. Pick a ratio, say how much starter you keep or how much fed starter you need, and see the grams of each, plus the hydration of the mix.
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How to use it
- Choose the feeding ratio.
- Enter either the weight of starter you keep, or the total weight you need after feeding.
- Weigh out the starter, flour and water. Mix, cover loosely and leave at room temperature until it peaks.
How it works
A ratio of 1 : n : n means flour and water are each n times the starter weight, so the total is starter × (1 + 2n). For a given total, starter = total ÷ (1 + 2n). Hydration after feeding = (starter water + added water) ÷ (starter flour + added flour), where the starter holds s ÷ (1 + h) of flour for hydration h.
Worked example
1:5:5 with 20 g of 100% starter: flour 20 × 5 = 100 g, water 100 g, total 220 g. The 20 g starter holds 10 g flour and 10 g water, so the mix is (10 + 100) ÷ (10 + 100) = 100% hydration.
Tips
- Discard before feeding; keeping a small amount of starter is what makes a high ratio economical.
- Feed at the same time each day to learn how long your starter takes to peak.
- Use the ripe starter in the bread hydration calculator to see the true dough hydration.
Frequently asked questions
What does a 1:5:5 ratio mean?
One part starter to five parts flour to five parts water, by weight. With 20 g of starter you add 100 g of flour and 100 g of water, for 220 g in total. Equal flour and water parts keep the starter at the same hydration, around 100% for a typical starter.
Which ratio should I use?
It is a matter of timing. A larger ratio such as 1:5:5 dilutes the starter, so it takes longer to peak; 1:1:1 peaks sooner. Warm kitchens and strong starters peak faster than cool ones, so judge by when yours rises and domes rather than by a fixed number of hours.
Why use weight and not cups?
A cup of flour weighs different amounts depending on how it is packed and which flour it is, so ratios by volume are inconsistent. A kitchen scale makes the feeding exact.
What if my starter is not 100% hydration?
Enter its hydration. The calculator then reports the hydration of the mix after feeding. A stiff starter at 50% fed with equal parts flour and water becomes wetter, around 80% in the 1:1:1 example.
How do I get the amount of starter for a recipe?
Choose Total I need, enter the weight you want after feeding, and the tool works backwards. For 300 g at 1:2:2 you need 60 g of starter, 120 g flour and 120 g water.