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Baker's Percentage: Flour = 100%, Scale Any Recipe
Baker's percentage (also called baker's math) is the professional system for expressing bread recipe ratios. Every ingredient is shown as a percentage of the total flour weight—and flour is always 100%. Our sourdough starter calculator uses baker's percentage under the hood.
The Core Concept
In baker's percentage, flour is always 100%. Every other ingredient is expressed as a percentage of that flour weight. So if a recipe says 72% hydration, it means 72g water per 100g flour. Salt at 2% means 2g salt per 100g flour. Levain at 20% means the flour in your starter equals 20% of total flour.
This system has one huge advantage: scaling. Want to double a recipe? Double the flour—and every percentage stays the same. Want 1.5 loaves? Multiply flour by 1.5, and all other ingredients scale proportionally.
How Baker's Percentage Works in Sourdough
Sourdough adds complexity because your levain (starter) contains both flour and water. So "total flour" = main dough flour + flour from starter. "Total water" = main dough water + water from starter. The levain percentage is (flour in starter ÷ total flour) × 100.
Our sourdough calculator handles this automatically. See our hydration calculation guide for the manual approach.
Standard Baker's Percentages for Sourdough
- Hydration: 65-85% (70-75% for beginners)
- Salt: 1.5-3% (2.1% is common)
- Levain: 10-30% (20% is typical)
These aren't rules—they're starting points. Our calculator lets you tweak any percentage and see results instantly.
Converting Recipes to Baker's Percentage
Divide each ingredient by total flour weight, multiply by 100. Example: 500g flour, 350g water, 10g salt. Hydration = (350÷500)×100 = 70%. Salt = (10÷500)×100 = 2%. Now you can scale to any batch size.
Why Professionals Use It
Baker's percentage is the industry standard. Our sourdough starter calculator speaks this language. For more on ratios, see our starter ratio guide.
Frequently Asked Questions
Flour is the primary ingredient. Expressing everything relative to it makes scaling and comparison easy.
Divide each ingredient by total flour, multiply by 100. (350g water ÷ 500g flour) × 100 = 70% hydration.
Typically 1.5-3%. 2.1% is a common default—good flavor and fermentation control.
Yes. Total flour and water include what's in your levain. Levain % = flour from starter ÷ total flour × 100.
Disclaimer: Baking results vary based on flour type, ambient temperature, starter health, and technique. Use this guide and our sourdough hydration calculator as a starting point, then adjust to your conditions.