Baker's Percentage, Explained

Baker’s percentage is a way of writing a recipe where every ingredient is expressed relative to the total flour, which is always 100%. Water, salt, starter, and any add-ins are each given as a percentage of that flour weight. Once a formula is written this way, you can scale it to any batch size and instantly compare it to other recipes.

The one rule

Flour is the baseline. Everything else is measured against it:

ingredient % = (ingredient weight ÷ total flour weight) × 100

A typical lean sourdough might read: flour 100%, water 75%, starter 20%, salt 2%. Those numbers describe the bread regardless of whether you’re making one loaf or twenty. (Note that percentages add up to more than 100% — that’s expected, because each one is relative to flour, not to the whole dough.)

Scaling a formula

Say you want a dough using 800 g of flour with the formula above:

• Water: 800 × 0.75 = 600 g
• Starter: 800 × 0.20 = 160 g
• Salt: 800 × 0.02 = 16 g

Want a bigger bake? Change only the flour weight and recompute. Nothing about the bread’s character changes — just the yield. This is why professionals share formulas in percentages instead of fixed gram amounts.

Why it’s worth learning

• Repeatability — the same percentages give the same bread at any size.
• Comparison — you can line up two recipes and see, at a glance, that one is wetter or saltier than the other.
• Troubleshooting — when a bake goes sideways, percentages tell you which lever to pull.

Baker’s percentage pairs directly with dough hydration — hydration is simply the water percentage. If you’d rather not run the arithmetic by hand each time, Sourdough Journal keeps baker’s percentage, hydration, scaling, and levain calculations tied to the formula you’re actually baking, and saves the result alongside your starter and bake notes.