Sourdough Starter Calculator
Calculate flour and water amounts to feed your sourdough starter at any ratio.
Total starter after feeding
Feeding breakdown
How Feeding Ratios Work
A feeding ratio is written as starter:flour:water. It tells you how much flour and water to add relative to the amount of existing starter you keep. With a 1:1:1 ratio you add the same weight of flour and water as the starter you keep, so 50 g of starter gets 50 g of flour and 50 g of water.
- 1:1:1 – a quick, strong feed that ripens fast. Good before baking or in a warm kitchen.
- 1:2:2 – a moderate feed that gives the starter more food and a longer rise.
- 1:3:3 – a larger feed for slower fermentation or warmer rooms.
- 1:5:5 – a big feed often used to slow things down or stretch the time between feedings.
The Math Behind the Numbers
This calculator splits the chosen ratio into its three parts – starter (s), flour (f) and water (w) – then scales the flour and water to the amount of starter you keep:
- flour to add = starter × (f / s)
- water to add = starter × (w / s)
- total after feeding = starter + flour to add + water to add
Note: Feeding ratios are a starting point, not a strict rule. Flour type, hydration, and room temperature all affect how your starter behaves. Adjust the ratio and timing to suit your kitchen and your baking schedule.