Baker's percentage:
write a recipe once, scale it to any batch

Why flour is always 100% in a baker's formula

Open a bakery recipe and the percentages add up to more than 100. That is not a mistake. In a baker's percentage the flour weight is the anchor, written as 100%, and every other ingredient is stated as a share of that flour. Water at 70% means 70 g of water for every 100 g of flour, however much dough you are making.

The system exists because bread is a ratio problem. A dough that is too wet or too salty behaves badly whether you mix 500 g or 50 kg, so the useful thing to record is the relationship between ingredients, not the quantities. Once you think this way, two recipes become easy to compare in a glance, and a failed batch can be diagnosed by looking at a handful of numbers.

Baker's percentages are not the same as the share of the finished dough. If water is 70% in the formula, it is about 40% of the dough by weight, because the dough also contains the flour itself. Mixing up those two readings is the most common source of confusion when people first read a professional recipe.

This page is about writing and scaling a whole recipe in this way. If you only want the water-to-flour figure for one dough, a dough hydration calculator does that single step; the baker's percentage approach extends it to salt, yeast, sugar, fat and everything else.

The formula: percentage from weights and weights from percentages

There are two directions to work in. To turn a recipe in grams into a formula, divide each ingredient by the total flour weight. To build a recipe from a formula, multiply each percentage by the flour weight, or work backwards from the dough weight you want.

Hydration is simply the water line of the same formula: water weight divided by flour weight. A 70% hydration dough has 70 g of water for 100 g of flour. Any liquid that is mostly water, such as milk, counts partly towards hydration, which is covered further down.

Worked example: scaling a basic loaf to 1,200 g of dough

Take a straight yeasted loaf with flour at 100%, water 70%, salt 2% and instant yeast 0.6%. The percentages sum to 172.6. You want 1,200 g of finished dough, enough for two sandwich tins.

Check the total before mixing: 695 + 487 + 14 + 4 = 1,200 g. If you want a smaller trial, change only the target. For 600 g of dough the flour is 348 g, and every other weight halves with it. Nothing about the formula changes, which is the whole point.

Salt and yeast quantities are tiny, so weigh them on a scale that reads to 0.1 g or use a pinch-and-taste approach for salt. A gram of error on 4 g of yeast is a 25% error in the rate, which will change your proving time noticeably.

Typical percentages for common doughs

The figures below are common starting points from bakery practice, not rules. Flours absorb different amounts of water, and your climate and kneading method matter, so use them as a sanity check rather than a target.

Salt at roughly 2% of flour weight is the one number that stays remarkably steady across bread styles. Too little and the loaf tastes flat and rises fast and sloppy; too much slows the yeast. If a recipe you find online is far outside these bands, work out its percentages before you trust it.

Starters, soakers and flour blends in the same formula

When the recipe uses more than one flour, the 100% is the sum of all of them. A formula of 80% white and 20% whole wheat still totals 100% flour, with each flour written as its own line.

A sourdough starter or poolish needs a little extra care because it carries both flour and water. A 100 g starter fed at equal weights of flour and water holds 50 g flour and 50 g water. If the final mix adds 450 g flour and 300 g water, the true totals are 500 g flour and 350 g water, so the real hydration is 350 ÷ 500 = 70%, not 300 ÷ 450 = 67%.

Bakers usually write the pre-ferment as its own column, then a total formula column. Keeping both lets you see the true hydration and also reproduce the dough step by step.

Mistakes that skew the numbers, and where percentages stop helping

• Using the dough weight instead of the flour weight as the base. Water at 350 g in a 863 g dough is 70% of the flour, not 40%.
• Counting a starter's water but not its flour, which overstates hydration.
• Treating milk, eggs or honey as dry. Milk is roughly 87% water, so 100 g of milk adds about 87 g to hydration.
• Measuring by cups for the original and by grams for the scaled version. Cup measures of flour vary by 20% or more depending on how you scoop.
• Forgetting add-ins such as seeds, nuts or raisins, which are usually listed as a percentage of flour but are not part of hydration.

Percentages also say little about process: fermentation time, temperature and folding technique change the loaf as much as the ratios do. Two bakers with the same formula can still get different bread.