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Sourdough starter feeding calculator

A 1:5:5 feed means one part starter to five of flour and five of water. Bigger ratios ferment slower and taste milder.

Starter you want at the end

Flour parts

Water parts

Starter you currently have

Flour to add

136.4g

= Exact Sourdough starter feeding Show in

Water to add: 136.4
Starter to keep as the seed: 27.3
Starter to discard or bake with: 122.7
Resulting starter hydration: 100.0 %
Most you could make from what you have: 1650

Show the working

Starter you want at the end = 300
Flour parts = 5
Water parts = 5
Starter you currently have = 150
parts = 1 + 5 + 5 = 11
Starter to keep as the seed = 300 / 11 = 27.2727
Flour to add = 27.2727 * 5 = 136.364
Water to add = 27.2727 * 5 = 136.364
Starter to discard or bake with = max(150 - 27.2727, 0) = 122.727
Resulting starter hydration = 5 > 0 ? 5 / 5 * 100 : 0 = 100
Most you could make from what you have = 150 * 11 = 1650

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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The formula

total parts = 1 + flour parts + water parts
seed = target weight / total parts

A larger feed ratio takes longer to peak, which is how bakers time a levain to be ready when they are.

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