Introduction: Why Bakers Count in Percentages
Professional bakers never write "2 cups of flour and 1 cup of water." They write formulas where every ingredient is a percentage of the total flour weight, which is always 100%.
This system - baker's percentage, or baker's math - makes recipes infinitely scalable and instantly comparable. A "70% hydration dough" tells a baker everything about how the dough will feel, behave, and bake, regardless of batch size.
This guide explains how the system works, how to read and write a formula, and how to scale any recipe up or down without the guesswork. Use the cooking guide for related kitchen conversions.
The One Rule: Flour Is Always 100%
In baker's math, the total weight of flour is set to 100%, and every other ingredient is expressed as a percentage of that flour weight.
So a basic white bread formula might read: flour 100%, water 65%, salt 2%, yeast 1%. If you use 1,000 g of flour, you need 650 g of water, 20 g of salt, and 10 g of yeast.
The percentages are ratios, not parts of 100 that must sum to a fixed number. A formula can add up to 168% or 175% - that is normal and expected. The flour is always the fixed reference point.
Hydration: The Number That Defines the Dough
Hydration is simply the water weight expressed as a percentage of flour weight: hydration = (water / flour) x 100.
A 60% hydration dough is stiff and easy to handle, typical for bagels and some sandwich loaves. At 70-75% you get a soft, extensible dough that makes beautiful open-crumb artisan loaves but is sticky to shape. At 80% and above you are in high-hydration territory that requires strong technique or a sourdough starter.
The same percentage works at any scale: a 70% hydration dough behaves the same whether it is 500 g of flour or 50 kg. That predictability is why professionals communicate in hydration numbers.
How to Scale Any Recipe
To scale a formula to a target total dough weight, first decide the flour weight, then multiply every percentage by it.
Given a formula whose percentages add up to 170% (100% flour + 65% water + 2% salt + 1% yeast + 2% oil), and a target batch of 1,700 g: divide 1,700 by 1.70 to get 1,000 g of flour, then water is 650 g, salt 20 g, yeast 10 g, oil 20 g.
If you only know the total from an old recipe in volume measures, convert everything to weight first - flour in particular varies wildly by cup because of packing. Weighing is the foundation of baker's math.
Reading a Professional Formula
Real bakery formulas often include a second flour: for example, "bread flour 85%, whole wheat 15%, water 68%, salt 2%, yeast 1%." Here the two flours together total 100%, and water is 68% of the combined flour weight.
Sourdough formulas express the starter separately: a "levain" or starter might be listed at 20%, and because the starter contains its own flour and water, it affects the final hydration calculation. Serious bakers track flour, water, and salt totals from both the dough and the starter to find true hydration.
Once you can read a formula, you can also compare recipes at a glance: a recipe with 72% hydration and 2.2% salt will handle and taste distinctly different from one at 62% hydration and 1.8% salt - no need to bake both to know.
Common Beginner Mistakes
The most common error is treating percentages as parts that must add to 100, then "fixing" the formula. Baker's percentages routinely exceed 100% - that is not a mistake.
A second error is ignoring the water in a starter or preferment when calculating hydration. If a formula calls for a 100% hydration starter, that starter is adding both flour and water that count toward the totals.
Finally, do not mix weight and volume. Baker's math only works when every ingredient is weighed, in the same units.
Frequently Asked Questions
- Q: Why is flour always 100%? A: Because every other ingredient ratio is defined relative to flour, making formulas scale-independent and comparable between bakers.
- Q: What is a good hydration for a beginner? A: Start at 62-65% - stiff enough to shape easily, wet enough to bake a soft crumb. Work up to 70%+ as your technique improves.
- Q: Does baker's percentage work for pastry? A: Yes. Formulas for brioche, croissants, and cookies all use the same principle, with butter and sugar expressed as percentages of flour.
- Q: How do I scale a recipe from 2 loaves to 10? A: Multiply the flour weight by 5 and every ingredient percentage by that new flour weight. The ratios stay identical.
Conclusion: Master the Ratio, Master the Bake
Baker's percentages turn baking from a recipe-following activity into an engineering one. Once the ratio is right, scaling is arithmetic, troubleshooting is obvious, and consistent results follow.
Write your next formula in percentages, weigh everything, and you will never guess at a recipe again.
Frequently Asked Questions
What does 70% hydration mean in baking?
It means the water weighs 70% of the flour weight. A 1,000 g flour dough at 70% hydration uses 700 g of water.
How do I convert a volume recipe to baker's percentages?
Weigh every ingredient first, then divide each weight by the flour weight and multiply by 100. Flour weight becomes 100% and everything else is a percentage of it.
Is a higher hydration always better?
No. Higher hydration gives a more open, moist crumb but makes dough sticky and harder to shape. Lower hydration is easier to handle and suits bagels, sandwich loaves, and some pastries.
Do eggs and butter count in baker's percentages?
Yes - every ingredient is a percentage of flour. In enriched doughs like brioche, butter and eggs can each be 20-60% of flour weight.