How this calculator works
A starter is itself part flour and part water. At 100% hydration, a 100 g starter is 50 g flour and 50 g water. The calculator splits the starter by its hydration, adds those amounts to the dough’s flour and water, and divides total water by total flour.
Starter flour = Starter ÷ (1 + Starter hydration%/100)
Starter water = Starter − Starter flour
Hydration = (Water + Starter water) ÷ (Flour + Starter flour) × 100
Assumptions and tips
- Water from other ingredients (milk, eggs, honey) is not counted.
- Whole-grain flours absorb more water, so the same hydration feels stiffer.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Flour | 500 g |
| Water | 350 g |
| Starter / levain | 100 g |
| Starter hydration | 100 % |
| Salt | 10 g |
| Result | Value |
|---|---|
| True hydration | 72.7 % |
| Hydration ignoring starter | 70 % |
| Total flour | 550 g |
| Total water | 400 g |
| Starter (inoculation) | 20 % of flour |
| Salt | 1.82 % of total flour |
| Dough weight | 960 g |
Step by step:
- Starter flour = 100 ÷ 2 = 50 g; starter water = 50 g
- Total flour = 500 + 50 = 550 g
- Total water = 350 + 50 = 400 g
- Hydration = 400 ÷ 550 × 100 = 72.7%
How starter changes true hydration
500 g flour, 350 g water, 100% hydration starter.
| Starter | True hydration |
|---|---|
| 0 g | 70 % |
| 50 g | 71.4 % |
| 100 g | 72.7 % |
| 150 g | 73.9 % |
| 200 g | 75 % |
Common mistakes to avoid
- Ignoring the starter’s water, which can raise hydration by several points.
Frequently asked questions
What hydration is good for sourdough?
Many beginner loaves sit around 65–72%. Higher hydration gives a more open crumb but is stickier to shape.
How much salt for sourdough?
About 2% of the total flour weight is typical.