Sourdough Starter Ratio Calculator

About this calculator

A sourdough starter's feeding ratio is expressed as starter : flour : water by weight — a 1:1:1 ratio feeds it with flour and water each equal to the starter's own weight, while a 1:5:5 ratio dilutes it much further, both of which control how quickly the culture ferments and how sour the resulting bread tastes. A tighter ratio like 1:1:1 ferments faster and suits bakers feeding once or twice a day, while a looser ratio like 1:5:5 slows fermentation and works well for less frequent feeding or a milder sour flavor.

Home bakers adjust this ratio deliberately rather than always defaulting to 1:1:1, because the ratio is one of the main levers for controlling both fermentation speed and flavor development — a starter fed too infrequently at a tight ratio can become overly acidic and weaken, while one diluted too much between feeds can starve and lose leavening power.

This calculator takes your starter's current weight and your chosen feeding ratio and returns exactly how much flour and water to add, so every feeding is precise instead of eyeballed.