Sourdough Starter Feeding Ratio Calculator

How Sourdough Feeding Ratios Work

A sourdough feeding ratio describes the proportion of starter to fresh flour to water you add at each feeding, written as starter:flour:water — 1:1:1 means equal parts of all three by weight, while 1:5:5 means five times as much fresh flour and water as starter. A lower ratio like 1:1:1 keeps the culture more active and sour, feeding quickly; a higher ratio like 1:5:5 or 1:10:10 stretches out the time between feedings and produces a milder flavor, since there's proportionally less mature starter (and its acids) diluting the fresh flour.

Which ratio to use depends on your schedule and how you like your bread to taste — bakers often use a low-maintenance ratio for storage and a higher, more frequent ratio in the days before a bake to build a strong, active culture.

How to Use This Calculator

Enter how much starter you're feeding (in grams) and your ratio — 1:1:1 is a common default, but adjust the three numbers to match your recipe. The calculator gives you the exact grams of flour and water to add, plus your total starter weight after feeding.

How We Calculate It

Flour needed = starter amount × (flour ratio ÷ starter ratio). Water needed uses the same formula with the water ratio. This scales any ratio to the exact amount of starter you're working with, so the proportions stay correct no matter how much you're feeding.

A Few Notes

This calculator assumes flour and water are measured by weight (grams), not volume — a kitchen scale gives far more consistent results than cups or tablespoons for sourdough. It also assumes you're using your existing starter as the base for the ratio, not throwing any away first; if your recipe calls for discarding starter before feeding, do that first and use the remaining amount as your starting figure here.