Final composition
Flour, water, and hydration after feeding
| Measure | Seed starter | Added | Final starter |
|---|---|---|---|
| Flour | 10 g | 40 g | 50 g |
| Water | 10 g | 40 g | 50 g |
| Hydration | 100% | 100% | 100% |
The seed composition assumes the retained starter consists only of flour and water at the hydration entered above.
Quick example
Build 180 g of starter at 1:2:2
A 1:2:2 feeding has five total ratio parts. Divide the desired 180 g by five to get 36 g per part. Use 36 g starter, 72 g flour, and 72 g water.
Reading the ratio
Starter comes first, then flour, then water
A ratio such as 1:2:2 means one part ripe starter, two parts fresh flour, and two parts water. All three parts are weights. The numbers describe proportions, so 10:20:20 and 25:50:50 are both 1:2:2 feedings.
1:1:1
Equal weights of starter, flour, and water. A common maintenance baseline.
1:2:2
Twice as much fresh flour and water as retained starter.
1:4:4
A larger meal relative to the seed starter, which generally takes longer to peak.
1:2:1
A stiffer feed with half as much added water as added flour.
Watch the starter, not the clock
A ratio cannot predict an exact peak time
Feeding ratio affects how much food the culture receives, but temperature, flour, starter strength, and maturity also affect fermentation speed. Use rise, bubbles, aroma, and the beginning of a fall as practical readiness cues. This calculator deliberately does not promise an exact fermentation time.
Method & source
Weight-based feeding math
King Arthur Baking's feeding-ratio guide defines the order as starter:flour:water and explains that the proportions are measured by weight. Its examples include 1:1:1, 1:2:2, and 1:4:4 feedings. The calculator uses that convention, then separates the seed starter into estimated flour and water to report the final hydration.
Common questions
Sourdough starter feeding FAQ
What does a 1:2:2 feeding ratio mean?
Use one part starter, two parts flour, and two parts water by weight.
How much starter makes 180 g at 1:2:2?
Use 36 g starter, 72 g flour, and 72 g water.
Do feeding ratios use weight or volume?
Weight. Flour and water do not have the same density, so equal volumes are not equal ratio parts.
Why enter the seed starter's hydration?
The seed already contains flour and water. Its hydration is needed to calculate the final starter's actual flour, water, and hydration.