How Much Sourdough Starter to Use (Calculator by Flour Weight)
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Sourdough recipes usually give the starter as a percentage of the flour weight, in baker's percentages. Multiply your flour by that percentage and you have the grams of starter to use.
The formula
starter (g) = flour (g) × starter % ÷ 100
A starter at h% hydration splits into flour = starter × 100 ÷ (100 + h) and water = starter × h ÷ (100 + h).
Examples for 500 g of flour
| Starter % | Starter | Flour in it (100% starter) | Water in it |
|---|---|---|---|
| 10% | 50 g | 25 g | 25 g |
| 15% | 75 g | 37.5 g | 37.5 g |
| 20% | 100 g | 50 g | 50 g |
| 25% | 125 g | 62.5 g | 62.5 g |
These percentages are examples to show the arithmetic. Use the percentage your recipe gives.
Making exactly that much starter
Once you know the grams you need, the feeding ratio calculator tells you how much starter, flour and water to mix at your usual ratio, with a little extra to keep back for the next feed.
Changing the amount of starter
Changing the starter percentage changes more than the starter line:
- Hydration. More starter adds more water and flour. Check the true hydration with the hydration calculator.
- Timing. The schedule your dough follows comes from your own bakes. If you change the starter amount, time a bake with the new amount at a known temperature and enter that in the schedule calculator, rather than reusing old times.
Sources
- Baker's percentage arithmetic. All numbers above are computed with it.