🍞 Baking
Leaven & Baking Scaler
Resize any bread or baking formula to the dough weight you need, in baker's percentages, with or without a sourdough leaven. Then convert a leaven from one hydration to another. Press Calculate.
About the leaven and baking scaler
Baker's percentage measures everything against the flour, so the flour is always 100% and every other ingredient is a share of its weight. That is what makes a formula scalable: a 68% hydration dough is 68% hydrated whether you bake one loaf or twenty. Type your current formula, choose what you are aiming for, and the whole list rescales together.
The second half handles sourdough. A leaven is part flour and part water, so when a formula says "20% leaven at 100% hydration" it is really contributing 10% flour and 10% water to the dough. This tool splits the leaven out and shows the true total flour and total water, which is the only way to know what hydration you are really mixing.
How baker's percentage works
| Ingredient | Weight | Baker's % |
|---|---|---|
| Bread flour | 500 g | 100% |
| Water | 340 g | 68% |
| Salt | 10 g | 2% |
| Fresh yeast | 5 g | 1% |
| Total dough | 855 g | 171% |
Yeast versus leaven
- Fresh yeast is the baseline; instant dry yeast is about one third of the fresh weight, and active dry about 40%.
- Sourdough leaven at 20% of the flour weight, fermented for 12 to 18 hours, behaves like roughly 1% fresh yeast in a warm kitchen.
- Holding the leaven percentage and changing the temperature is the main way to control timing: warmer means faster.
- For a long cold retard, raise the leaven to 25% and drop the temperature to 4 °C overnight.
Levain build ratios and timing
| Build (starter : flour : water) | 26 °C | 21 °C | 16 °C | 4 °C |
|---|---|---|---|---|
| 1 : 1 : 1 | 3 – 4 h | 4 – 6 h | 6 – 9 h | 24 h+ |
| 1 : 2 : 2 | 5 – 6 h | 6 – 9 h | 9 – 12 h | — |
| 1 : 5 : 5 | 8 – 10 h | 10 – 12 h | 12 – 16 h | 24 – 36 h |
| 1 : 10 : 10 | 10 – 12 h | 12 – 16 h | 16 – 20 h | 36 – 48 h |
Worked examples
- Scaling a 500 g flour formula at 68% hydration to 1,000 g of dough needs a factor of 1000 ÷ 855 = 1.17, giving 585 g flour and 398 g water.
- 20% leaven at 100% hydration on 500 g flour is 100 g of leaven, made of 50 g flour and 50 g water.
- Total flour in that dough is 550 g and total water is 340 + 50 = 390 g, so the real hydration is 390 ÷ 550 = 70.9%.
- Taking 200 g of 100% leaven to 65% hydration means adding 53.8 g of flour, which yields 253.8 g of stiffer leaven.
Frequently asked questions
Common mistakes to avoid
- Adding the leaven on top of the flour but calling it hydration. Split it out, as this tool does.
- Scaling salt and yeast by eye. They are small numbers, and a 0.5% error in salt is a noticeable change in taste.
- Assuming a recipe doubles its time when doubled. Larger doughs ferment a little slower, because they hold their heat and take longer to cool.
- Using a scale that rounds to 5 g for a small batch. For anything under 100 g total, use 0.1 g resolution.