Baker's Percentage Explained

What Are Baker's Percentages?

Baker's percentage is a standardized way of expressing bread recipes where every ingredient is measured relative to the total weight of flour. Flour is always 100%, and every other ingredient is a percentage of that flour weight. Water, salt, starter, seeds, oil — each has its own percentage that describes its proportion to the flour.

This system may seem counterintuitive at first. In conventional cooking, recipes are lists of fixed amounts: 500 grams of flour, 350 grams of water, 10 grams of salt. In baker's percentages, the same recipe becomes 100% flour, 70% water, 2% salt. The advantage is immediate: you can see the dough's character at a glance. A recipe at 65% water is firm; one at 85% is slack. A recipe with 20% starter ferments faster than one with 10%.

Professional bakers use percentages because they are universal. A formula written in baker's percentages can be scaled to any size — from a single home loaf to a commercial batch of two hundred — without any conversion math beyond multiplication. It also makes substitutions and experiments trivial. If you want to try 3% salt instead of 2%, you change one number and every other ingredient adjusts proportionally.

How to Calculate Baker's Percentages

The math is simple. Divide the weight of any ingredient by the total weight of flour, then multiply by 100. That gives you the baker's percentage for that ingredient.

Let us walk through an example. Suppose you have a recipe with 500 grams of bread flour, 375 grams of water, 10 grams of salt, and 100 grams of starter. The flour is 100% by definition. The water is (375 ÷ 500) × 100 = 75%. The salt is (10 ÷ 500) × 100 = 2%. The starter is (100 ÷ 500) × 100 = 20%. Written as a formula, this becomes:

Note that starter is usually counted at full weight in the formula, even though it is itself a mixture of flour and water. Some advanced bakers separate starter into its flour and water components for precise hydration calculations, but for everyday baking, counting starter as a standalone ingredient at its given percentage is standard practice and works perfectly well.

Common Sourdough Recipes by Percentage

Once you internalize a few reference formulas, you can improvise endlessly. Here are the baker's percentages for several classic sourdough styles. Each assumes 100% flour, with the other ingredients expressed as percentages of that flour.

Notice how salt stays remarkably consistent at 2% across almost every style. This is because salt strengthens gluten, controls fermentation speed, and enhances flavor. Deviating far from 2% produces noticeable effects: below 1.5%, dough ferments too quickly and tastes bland; above 2.5%, yeast activity slows dramatically and the bread can taste unpleasantly salty.

Scaling Recipes Using Percentages

Scaling is where baker's percentages truly shine. If you know your percentages and you know how much flour you want to use, every other ingredient is one multiplication away.

Suppose you want to bake two loaves and your formula is 100% flour, 75% water, 2% salt, 20% starter. You estimate 500 grams of flour per loaf, so you need 1000 grams total. The math becomes:

What if you want to work backward from total dough weight? This is common when you have a specific target, such as a 900-gram loaf to fit your banneton. First, add all the percentages in your formula. For 100% flour + 75% water + 2% salt + 20% starter, the total is 197%. Then divide your target dough weight by this total and multiply by 100 to find the flour weight.

This backward calculation is exactly what our sourdough calculator does when you switch to "Total Dough Weight" mode. Enter your target weight, set your percentages, and the tool instantly computes every ingredient. No algebra required.

Why Professionals Never Use Volume Measurements

A cup of flour can weigh anywhere from 120 grams to 150 grams depending on how it is scooped, sifted, or packed. That is a 25% variance — enough to turn a 70% hydration dough into a 55% hydration brick or an 85% hydration soup. Water is slightly more consistent, but still imprecise. Starter, with its bubbles and variable density, is the worst offender of all when measured by volume.

Weight is absolute. A gram is a gram. When you share a recipe in baker's percentages, any baker in the world can reproduce it exactly with a digital scale. When you share a recipe in cups and tablespoons, you are sharing an approximation. Serious baking demands precision, and baker's percentages paired with a scale deliver it effortlessly.

If you are just starting out, buy a digital scale that measures in grams with 1-gram resolution. It is the single best investment you can make in your baking journey, and it costs less than a bag of good bread flour.