Sourdough Starter Ratio
Free Sourdough Starter Ratio calculator with clear step-by-step results.
About Sourdough Starter Ratio
A feeding ratio describes parts of existing starter to flour to water, so a 1:2:2 feed on 50 grams of starter means 100 grams of flour and 100 of water. The water figure is adjusted for starter hydration, and the surplus line tells you whether the feed produces enough levain for the bake plus what you keep back.
Formulas
Feed quantities
Flour = starter kept x flour parts; water = starter kept x water parts x hydration
Surplus
Surplus = total after feed - levain needed - starter kept back
Worked example
With the default values below, Sourdough Starter Ratio returns Flour to add of 100.0. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Starter you are keeping backminimum 1 g
- 50 g
- Feeding ratio (starter : flour : water)one of 1:1:1 - fast, ready in 4-6 h, 1:2:2 - standard, ready in 6-8 h, 1:5:5 - slow, ready in 10-12 h, 1:10:10 - very slow, overnight plus
- 1:2:2 - standard, ready in 6-8 h
- Starter hydrationaccepts 50–200 %
- 100 %
- Levain needed for the bakeminimum 0 g
- 200 g
Results
- Flour to add
- 100.0 g
- Water to add
- 100.0 g
- Total starter after feeding
- 250.0 g
- Surplus after the bake and next keep
- 0.0 g
Step by step
- 1Values used
- 2Feed quantities
- 3Surplus
- 4Flour to add= 100.0 g
- 5Water to add= 100.0 g
- 6Total starter after feeding= 250.0 g
- 7Surplus after the bake and next keep= 0.0 g
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax 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
Which ratio should I use?
Higher flour ratios take longer to peak, which suits a fridge-kept starter or an overnight build. A 1:1:1 feed peaks in a few hours and needs using promptly.
What if the surplus is negative?
The feed is too small to supply both the levain and the next generation. Either keep back more starter or feed at a larger ratio.