Sourdough Starter Feeding Calculator

Work out sourdough starter feeding instantly with clear inputs, formula shown and shareable results.

About Sourdough Starter Feeding Calculator

A feed is expressed as starter : flour : water parts, so the flour and water added are the kept starter weight multiplied by their respective ratios, assuming the kept starter is itself at 100% hydration. Feeding by ratio rather than by eye keeps the acidity and rise time predictable, which is what makes a starter reliable enough to schedule a bake around.

Formulas

Feed quantities

flour = starter x flour parts; water = starter x water parts

Resulting hydration

hydration % = total water / total flour x 100

Worked example

With the default values below, Sourdough Starter Feeding Calculator returns Flour to add of 50.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Starter you are keepingminimum 1 g: 50 g
Flour parts per part of starterminimum 0.1: 1
Water parts per part of starterminimum 0.1: 1

Results

Flour to add: 50.0 g
Water to add: 50.0 g
Starter weight after feeding: 150.0 g
Resulting hydration: 100.0%

Step by step

1Values used
2Feed quantities
3Resulting hydration
4Flour to add= 50.0 g
5Water to add= 50.0 g
6Starter weight after feeding= 150.0 g
7Resulting hydration= 100.0

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Sourdough Starter Feeding figure worked out?

flour = starter x flour parts; water = starter x water parts. A feed is expressed as starter : flour : water parts, so the flour and water added are the kept starter weight multiplied by their respective ratios, assuming the kept starter is itself at 100% hydration.

Why does this matter?

Feeding by ratio rather than by eye keeps the acidity and rise time predictable, which is what makes a starter reliable enough to schedule a bake around.

What do I need to enter?

Enter starter you are keeping, flour parts per part of starter, water parts per part of starter. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.