Baker's Percentages: Bakery Math for Sourdough, Explained
By Maya Ellison · Updated August 18, 2026 · 6 min read
Quick answer
Bakery math sounds intimidating, but it’s the single most useful skill in sourdough baking: it’s how bakers compare recipes, predict dough behavior, and fix problems before they happen.
Baker’s percentage calculator
Enter the total flour weight and the percentages you want. Everything is computed in grams.
| Ingredient | Percentage | Weight |
|---|---|---|
| Bread flour | 100% | 500 g |
| Water | 75% | 375 g |
| Sourdough starter | 20% | 100 g |
| Salt | 2% | 10 g |
| Total dough | 985 g |
Note: this recipe uses an equal-flour starter (100% hydration). The starter’s own flour and water are not counted in the totals above.
How baker’s percentages work
Every ingredient is a percentage of the total flour weight, which is always 100%. Water, starter, and salt are all expressed relative to that. A classic sourdough formula looks like this:
| Ingredient | Percentage | Weight (500 g flour) |
|---|---|---|
| Bread flour | 100% | 500 g |
| Water | 75% | 375 g |
| Sourdough starter | 20% | 100 g |
| Salt | 2% | 10 g |
Why hydration is the number that matters
Hydration — the water percentage — predicts almost everything about your dough: 60% hydration makes a stiff, easy loaf; 75% is the classic open-crumb neighborhood; 85–90% is advanced territory. Once you know a recipe’s hydration, you know roughly what the dough will feel like before you ever touch it, which is why every recipe on this site states its hydration.
Common mistakes in bakery math
- Forgetting the starter’s flour and water. A 100% hydration starter is half flour, half water. Some formulas count it; this site’s recipes don’t — read each recipe’s assumption.
- Measuring hydration by volume. A “75%” dough must be weighed. Cups of flour vary by 20% depending on how they’re scooped.
- Scaling salt with the flour. Salt stays at about 2% of flour at any batch size — a common beginners’ scaling error.
- Ignoring the environment. Percentages fix ratios, not schedules. The same 75% dough rises faster in July than January.
How to use the calculator
Set your flour weight, then dial in hydration, starter, and salt. The table updates instantly in grams. Start at 75% hydration, 20% starter, 2% salt — that’s the classic balance behind most of the loaves on this site, including the main sourdough bread recipe.