Sourdough Starter Feeding Calculator

How the feeding ratio works

A sourdough feeding ratio is written as three numbers — starter : flour : water. A 1:5:5 feed means for every 1 part of old starter you keep, you add 5 parts fresh flour and 5 parts water by weight. So 50 g of kept starter becomes 50 g starter + 250 g flour + 250 g water = 550 g total. This calculator does that arithmetic instantly for any ratio and any amount you decide to keep.

The bigger the flour and water numbers, the more fresh food the yeast and bacteria have to work through, so the starter rises and peaks more slowly. Low ratios like 1:1:1 peak in a few hours and suit same-day baking; high ratios like 1:10:10 stretch the timeline for overnight or cool-kitchen feeds.

How to use it

1. Weigh how much starter you want to keep and type that into the grams box (discard or bake with the rest).
2. Set your feeding ratio in the three boxes, or tap a preset like 1:5:5.
3. Read off the exact grams of flour and water to stir in, plus the total weight after feeding.
4. Adjust the ratio to hit a faster or slower rise, then mix and mark your peak time.

FAQ

What ratio should I feed at?

1:1:1 for a quick same-day boost, 1:2:2 to 1:5:5 for everyday maintenance, and 1:10:10 when you want it to last overnight or between fridge feeds. Warmer kitchens favor higher ratios.

What hydration does this give?

When the flour and water parts are equal (like 1:5:5) the feed is 100% hydration. The note under the results shows the hydration for whatever ratio you enter.

Do I have to keep a fixed amount of starter?

No — keep whatever you like. Keeping less means less flour used per feed. The math scales to any starting weight you type in.

Is this only for wheat flour?

The weights work for any flour, but rye and whole-grain absorb more water and ferment faster, so you may want a higher ratio or a touch more water. Results are estimates — trust your starter's rise and smell.