🍞 Sourdough Starter Feeding Ratio Calculator
Enter your desired total starter amount and feeding ratio (starter:flour:water) to see exactly how much of each to combine.
Working backwards from the total
You choose how much starter you want to end up with, and the ratio decides how that weight is divided. The parts are added, the total split between them:
per part = desired total g / (starter + flour + water parts)
starter = per part × 1
flour = per part × flour parts
water = per part × water partsThe defaults are 300 g at 1:2:2, which is five parts of 60 g: keep 60 g of ripe starter, feed it 120 g of flour and 120 g of water. Everything above that 60 g is discard, or better, goes into pancakes.
Which ratio, and when
| Ratio | 300 g becomes | Time to peak at 75 °F |
|---|---|---|
| 1:1:1 | 100 g + 100 g + 100 g | 3-5 hours |
| 1:2:2 | 60 g + 120 g + 120 g | 5-7 hours |
| 1:3:3 | 43 g + 129 g + 129 g | 7-9 hours |
| 1:5:5 | 27 g + 136 g + 136 g | 10-12 hours |
A small ratio like 1:1:1 peaks fast and sours quickly, which suits a starter you are reviving or baking with the same afternoon. A large one like 1:5:5 feeds the culture more, stretches the rise overnight and keeps the flavour milder. Flour and water are always equal here, so the result is a 100% hydration starter; a stiff starter needs its own maths.
Frequently asked questions
What does a 1:2:2 sourdough ratio mean?
One part existing starter to two parts flour and two parts water, by weight. For a 300 g total that is 60 g, 120 g and 120 g.
How much flour and water do I feed 100 g of starter?
At 1:2:2, 200 g of each, for 500 g in total. If that is more starter than you want, set the desired total to 300 g and keep only 60 g of the old one.
Which ratio should I use before baking?
Feed at 1:3:3 or 1:5:5 the night before. The larger ratio times the peak to roughly when you want to mix dough, and a starter used at its peak lifts a loaf better than one that has already collapsed.