Guide
Baker's Percentage Explained
Baker's percentage is the universal language of professional baking. Every ingredient is expressed as a percentage of total flour weight — flour is always 100%, water is usually 55-85%, salt is 1.8-2.5%, and levain is 15-25% for sourdough. This system scales recipes up or down cleanly and lets you compare different formulas at a glance.
What is baker's percentage?
Baker's percentage is a standardized formula notation where every ingredient is expressed as a percentage of total flour weight. Flour is always 100%, the reference. If a recipe calls for 1000g of flour, 750g of water is written as 75% hydration. 20g of salt is 2%. 200g of levain is 20%. The system originated in professional European bakeries and is now the default in every serious baking textbook (Hamelman, Reinhart, Suas) and the spine of modern recipe sharing online.
The value of the system is three-fold. First, scaling: to double a recipe, multiply every weight by 2 and the percentages stay identical. Second, comparison: looking at a 75% hydration country loaf vs a 82% ciabatta tells you immediately why one has tight crumb and the other has large open holes. Third, standardization: two bakers in different countries can share recipes without ambiguity about cup sizes or volumetric measurements.
The four core percentages every recipe has
Sourdough recipes revolve around four percentages. Flour is always 100% by convention — even when flour is not literally 100% of the dough weight. Hydration (water as % of flour) typically runs 55-85%, with 65-75% being the artisan hearth-loaf sweet spot. Salt is expressed as a percentage of flour weight, nearly always 1.8-2.5%, with 2.0% being the modern bakery default. Levain (sourdough pre-ferment) is also expressed as a percentage of the final dough's flour weight, typically 15-25% for a lean hearth loaf and up to 30% for enriched doughs.
Worked example 1: Scaling a recipe
Start with a country loaf at 500g flour: 75% hydration (375g water), 2% salt (10g), 20% levain (100g). To scale up for a larger boule, just multiply by 2: 1000g flour, 750g water, 20g salt, 200g levain. Every percentage is preserved. This linear scaling works because baker's percentage is proportional — no volumetric conversions, no guess-work.
Worked example 2: Comparing two recipes
Compare Tartine-style country loaf (75% hydration, 15% levain, 2% salt, 85/10/5 bread/whole-wheat/rye) to Hamelman pain de campagne (75% hydration, 15% levain, 2% salt, 75/15/10). Same hydration and salt — the difference is in the flour blend. Hamelman's version has more whole grain, predicting a slightly denser crumb with deeper flavor. The percentages tell you the structural intent before you bake a single loaf.
Worked example 3: Adjusting hydration
A 70% recipe giving you tight crumb? Push to 75%. On 500g flour: 350g water becomes 375g water — 25g more. Everything else stays the same. What changes in technique: higher hydration needs longer stretch-and-folds, wetter hands during handling, and probably a cold retard to make shaping manageable.
Worked example 4: Substituting flour types
Recipe calls for bread flour at 75% hydration, but you have only whole wheat. Whole wheat's absorption multiplier is 1.075× bread flour (it drinks ~7.5% more water). Your 75% bread-flour hydration becomes an effective 80.6% with whole wheat at the same water weight. To hit the original crumb target, either increase water to ~81% explicitly, or accept a slightly tighter crumb. Our absorption table on the flour pages handles this math for every flour type.
FAQ
Do I include sourdough starter weight in baker's percentage?
Yes, but in a specific way. The starter contains flour and water — count those contributions toward total flour and total water. This is called the starter discount, and our calculator does it automatically. See the starter discount guide for worked examples.
Why is flour always 100% even when it's not literally 100% of the dough?
Convention. The Swiss and French professional baking traditions that gave us baker's percentage chose flour as the anchor because it's the ingredient around which everything else is proportioned. 'Flour = 100%' is the mathematical reference point — the dough weight is always more than that because water, salt, and levain add on top.
How do I convert a volume recipe (cups) to baker's percentage?
Weigh everything first. One cup of flour varies from 120g (sifted) to 150g (scooped), so volumes are unreliable. Weigh the flour, divide every other weight by the flour weight, multiply by 100. That's the baker's percentage. Our reverse calculator does this automatically from weights.