What Is Baker's Percentage?

Baker's percentage is the notation professional bakers use to write recipes. Instead of listing amounts, it lists each ingredient as a percentage of the flour weight, with flour always set to 100 percent. A formula written this way works at any batch size: the same numbers make one loaf or one hundred. Every calculator on this site, from the pizza dough calculator to the bread hydration calculator, is this one idea with a user interface on top.

The formula

For any ingredient:

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

That is the whole thing. Flour is the reference, so flour is always exactly 100 percent. Water at 68 percent means 68 grams of water for every 100 grams of flour; that particular ratio has its own name, hydration, because it matters more than any other. Salt at 2 percent means 2 grams per 100 grams of flour. Note two things that trip people up. First, the percentages are not shares of the total, so they do not add up to 100; a simple bread formula might read 100 plus 68 plus 2 plus 1, for a total of 171 percent. Second, everything is measured by weight, in grams. Cups and tablespoons vary too much for ratios this tight, which is why a scale is the first tool worth buying.

A worked example

Take a plain loaf built on 500 grams of flour:

Flour: 500 g, which is 100% by definition
Water: 340 g, so 340 / 500 = 68% hydration
Salt: 10 g, so 10 / 500 = 2%
Instant yeast: 5 g, so 5 / 500 = 1%

Total dough: 855 grams, and the formula reads 100 / 68 / 2 / 1. Now suppose you want that same bread, but exactly 1,200 grams of dough for two loaf pans. Working backwards is one division: the total equals flour times 1 plus the other percentages as decimals, here 1 + 0.68 + 0.02 + 0.01 = 1.71. So flour = 1,200 / 1.71, about 702 grams, and everything else follows by multiplication: about 477 grams of water, 14 of salt, 7 of yeast. Same bread, different size, no guesswork. The dough calculator runs both directions of that math for you, starting from either the flour you have or the total dough you need.

Why professionals write recipes this way

It scales perfectly. Ratios do not care about batch size. A formula proven at home works in a production bakery unchanged.
It makes recipes comparable. Told that one dough is 65 percent hydration and another is 80, you already know how each will feel in your hands before touching either. Gram amounts alone tell you nothing until you do the division.
It exposes mistakes. A recipe calling for 4 percent salt or 0.2 percent water is obviously wrong at a glance. Errors hide much more easily in raw weights.
It travels well. Bakers can trade formulas in a few numbers: a ciabatta might be written 100 / 80 / 2 / 0.3. That one line is the entire recipe.

Common mistakes

Expecting the percentages to total 100. They will not, and nothing is wrong. The total percentage (171 in our example) is actually useful: it is the number you divide by when scaling to a target dough weight.
Measuring by volume. A cup of flour can swing by 20 percent or more depending on how it is scooped. Baker's percentages assume weights; use grams.
Forgetting the flour and water inside a preferment. A sourdough starter or poolish is itself part flour, part water. Ignore that and your true hydration is off by several points. The sourdough hydration calculator splits the starter out automatically.
Comparing hydration across different flours. Whole wheat and high-protein flours absorb more water, so 70 percent in one flour does not feel like 70 percent in another. Treat published hydrations as starting points, not laws.
Chasing precision the dough cannot feel. Round to the gram for small ingredients and stop there. The math is exact; flour, humidity, and fermentation are not.

Where the system stretches

Two edge cases are worth knowing. Hydration can exceed 100 percent: batters and some very wet preferments carry more water than flour, and the notation handles that without complaint. And when a recipe uses several flours, they together make up the 100 percent, split however the formula says, for example 80 percent bread flour and 20 percent whole wheat. Everything else still keys off the combined flour weight.

Put it to work

The fastest way to internalize baker's percentage is to bake with it a few times. Start with the generic dough calculator to convert a favorite recipe into a formula, check your loaf's water content with the bread hydration calculator, or let the pizza dough calculator apply the system to dough balls and styles. For more on how these numbers play out in practice, see pizza dough hydration by style and the pizza dough ball weight guide.