How this instrument works
Baker's percentage — also called baker's math — is a notation where flour is always defined as exactly 100%, and every other ingredient in a formula is expressed as a percentage of that flour weight rather than of the total batch. A dough with 1,000 g of flour and 650 g of water is written as 65% hydration, regardless of whether the batch makes one loaf or fifty — the percentage describes the recipe's structure, not any particular batch size.
This differs from an ordinary recipe percentage, which usually means an ingredient's share of the total mixture. Because baker's percentages are all anchored to the same fixed flour figure, they don't have to add up to 100% — a lean bread dough might show flour 100%, water 65%, salt 2%, and yeast 1.2%, numbers that simply sit side by side rather than summing to a whole.
The payoff is scaling: multiply every ingredient's weight by the same factor and every percentage stays identical, so a baker can jump from a 1 kg test batch to a 50 kg production batch without recalculating ratios, and can compare two completely different-sized formulas — a home recipe and a commercial one — on equal footing just by reading their percentages side by side.
- Enter the ingredient's weight in Ingredient weight (g) — water, salt, yeast, sugar, or any other component of the formula.
- Enter Flour weight (g) — the total weight of all flour in the recipe, since every percentage is measured against this figure.
- Read Baker's percentage (%) — the ingredient's weight expressed relative to the flour, updated as either figure changes.
- Repeat for each ingredient to build a full breakdown; percentages don't need to sum to 100% since each is measured against flour, not the total.
Worked example — 650 g water against 1,000 g flour
A rustic bread formula calls for 1,000 g of flour and 650 g of water. Dividing 650 by 1,000 gives 0.65, and multiplying by 100 gives a baker's percentage of 65.0% — read directly as the dough's hydration.
That 65% figure describes the formula's structure regardless of batch size: doubling to 2,000 g flour and 1,300 g water, or scaling down to 500 g flour and 325 g water, both still show exactly 65.0% hydration, because the ratio between water and flour never changed.
Questions
Why is flour always set to exactly 100% instead of the whole batch?
Because flour is the one ingredient present in essentially every bread, cake, or pastry formula, using it as a fixed baseline lets every other ingredient's percentage describe the same relationship no matter how big or small the batch is. If percentages were instead measured against the total batch weight, they would shift every time you changed a single ingredient's amount, defeating the purpose of a stable, scalable notation.
Do all the percentages in a formula have to add up to 100%?
No, and this is the detail that trips up people new to baker's math. Because every percentage is measured against flour rather than against the total, a typical lean dough's percentages — flour 100%, water 65%, salt 2%, yeast 1.2% — sum to well over 100%. That total is meaningless on its own; what matters is each individual ingredient's ratio to the flour.
How do I handle a recipe with more than one type of flour?
Add every flour together first — whole wheat, rye, all-purpose, whatever the formula calls for — and that combined weight becomes the 100% baseline. Each individual flour then also gets its own baker's percentage against that same combined total, so a formula might read 80% bread flour, 20% whole wheat flour, alongside the usual water, salt and yeast percentages.
What's a typical hydration percentage for different bread styles?
Sandwich loaves and bagels commonly sit around 55-60% hydration, a standard rustic bread formula like the worked example runs roughly 65-70%, and high-hydration styles such as ciabatta or ultra-open-crumb sourdough can reach 80% or higher. Higher hydration generally produces a more open, irregular crumb and a stickier, harder-to-handle dough.
Can baker's percentage be used for cakes and cookies, not just bread?
It can, but it's less standard there — cake and cookie formulas are traditionally scaled using true batch percentages (each ingredient as a share of the total mix) rather than a flour-anchored baker's percentage, since bread's defining variable is hydration while cakes balance fat, sugar and liquid against each other. Bakeries that do use baker's math for enriched doughs and viennoiserie apply the exact same flour-as-100% convention shown here.