Baker's percentage writes every ingredient as a share of the flour, and the flour is always 100%. A dough of 1,000 g flour, 720 g water and 20 g salt is 100% flour, 72% water and 2% salt. The point is scaling: to make any amount of dough, divide the total weight you need by the sum of the percentages, and that's the flour; every other ingredient is the flour times its percentage. In the example below, 80 loaves of taro sourdough at 900 g each, plus 2% for loss, need 73.4 kg of dough; the percentages add up to 209%, so the flour is 35.1 kg and the water 25.3 kg. Counting the flour and water inside the levain, the dough's true hydration is 74.5%, not the 72% the formula shows, and the batch costs $117.02 in ingredients, $1.46 a loaf. Below is the formula, scaling, hydration with a levain, turning grams into percentages, the cost, and a free calculator.
The short version
- Flour is 100%; every other ingredient is its weight ÷ the flour's weight.
- Flour for a batch = total dough ÷ the sum of the percentages.
- Each ingredient = flour × its percentage.
- Hydration = water ÷ flour; count the levain's flour and water for the true figure.
- Add a little for loss in mixing and dividing, 2% in the example.
- Cost the dough from the grams and your prices per kilogram, then divide by the loaves.
- TaroStack keeps the recipe in grams, converts the units, and costs every batch from what you paid. More below.
The formula
| Ingredient | Grams in the recipe | Baker's % |
|---|---|---|
| Bread flour | 900 | 90% |
| Whole wheat flour | 100 | 10% |
| Water | 720 | 72% |
| Levain, 100% hydration | 200 | 20% |
| Salt | 20 | 2% |
| Cooked taro | 150 | 15% |
| Total | 2,090 | 209% |
The two flours add up to 1,000 g, so they're the 100%, split 90% and 10%. Every other ingredient is divided by 1,000. The total of 209% means the whole dough weighs 2.09 times the flour.
Scaling to any batch
Windward Roots, the made-up taro business I use in these examples, bakes 80 loaves of taro sourdough for its Saturday market:
| Step | Working | Result |
|---|---|---|
| Dough needed | 80 loaves × 900 g × 1.02 for loss | 73,440 g |
| Flour | 73,440 ÷ 2.09 | 35,139 g |
| Bread flour | 35,139 × 90% | 31,625 g |
| Whole wheat flour | 35,139 × 10% | 3,514 g |
| Water | 35,139 × 72% | 25,300 g |
| Levain | 35,139 × 20% | 7,028 g |
| Salt | 35,139 × 2% | 703 g |
| Cooked taro | 35,139 × 15% | 5,271 g |
One division and six multiplications, for any number of loaves. Doubling a home recipe by eye can't do that, because salt and levain don't scale by eye. How the whole bake day is planned around these numbers is in bakery production planning, and how to bring a cups-and-spoons recipe into grams first is in scaling recipes for production.
Hydration, with the levain counted
Hydration is water ÷ flour. On the formula, it's 72%. But the levain is half flour and half water at 100% hydration, so its 7,028 g holds 3,514 g of flour and 3,514 g of water that the formula's percentages don't show:
| Flour | Water | Hydration | |
|---|---|---|---|
| Formula, levain not counted | 35,139 g | 25,300 g | 72.0% |
| True, with the levain's flour and water | 38,653 g | 28,814 g | 74.5% |
The true figure is the one that tells you how the dough will handle, and it's the one to compare when two bakers' formulas don't feel the same. The cooked taro brings water of its own too, which is why a taro dough feels wetter again than 74.5% suggests.
What the dough costs
| Ingredient | Grams | Price per kg | Cost |
|---|---|---|---|
| Bread flour | 31,625 | $2.47 | $78.11 |
| Whole wheat flour | 3,514 | $3.40 | $11.95 |
| Water | 25,300 | $0.00 | $0.00 |
| Levain, half flour and half water | 7,028 | $1.24 | $8.68 |
| Salt | 703 | $2.00 | $1.41 |
| Cooked taro | 5,271 | $3.20 | $16.87 |
| Batch | 73,441 | $117.02 | |
| Per loaf (÷ 80) | $1.46 |
The levain is costed as the flour inside it. That's ingredients only; the bag, the label, the oven and your hours come on top. What a loaf costs in full, and what to charge, is in how to price sourdough bread.
Turning a recipe in grams into percentages
To convert a recipe you already make: add up the flours, then divide every ingredient by that total. 900 g of bread flour and 100 g of whole wheat make 1,000 g of flour; 720 g of water ÷ 1,000 = 72%. Once a recipe is in percentages, it scales to any batch with the formula above, and two recipes can be compared at a glance.
Get the calculator
Download the baker's percentage calculator. Type your formula in percentages, how many loaves, the dough per loaf and the extra for loss; it works out the flour and every other ingredient, the formula and true hydration with the levain counted, and the cost of the batch and a loaf. A second sheet turns a recipe in grams into percentages. It's an ordinary Excel file with no macros, and it works in Google Sheets, LibreOffice and Numbers.
Where this stops working
The calculator scales one dough. The bakery has six, sharing two flours, a levain and a walk-in, and the cost of a loaf depends on which bag of flour it came from: the one bought at $2.47 a kilogram or the one at $2.71 since the mill's price rise. Meanwhile 73 kg of dough a week comes out of stock that nobody takes off the books, so the flour on the shelf never matches the flour in the spreadsheet.
How TaroStack does it
TaroStack keeps each formula as a recipe, takes what it uses off stock, and costs every batch.
Formulas as recipes, in grams. Each dough is a recipe, with the levain as a sub-recipe of its own, and units convert: buy flour by the 50 lb bag, bake by the gram. Recipes have versions, so the formula you changed in March is a new version, and the batches before it keep the old one.
Every batch, off stock and costed. Recording a batch takes the flour, taro and salt off stock from the lots used, notes them automatically, and divides the cost, at what you paid for each lot, by the loaves that came out good. When the flour goes up, the next batch's cost shows it. Recipe truth checks, from your own batch history, whether a dough yields what its recipe claims.
And the flour on the shelf, right. Because every batch takes its flour off stock, the reorder list shows flour in days of cover against your supplier's lead time, and a count finds the difference, valued, before you post it.
| The job | Calculator | In TaroStack |
|---|---|---|
| Scale a formula | Type the loaves | A batch of any size, from the recipe |
| Cost per loaf | Last price you typed | Every batch, at what you paid |
| Flour used this week | Not recorded | Taken off stock by every batch |
| When to reorder flour | Look at the bags | Days of cover, against lead time |
Recipes with sub-recipes and versions, unit conversion, batches and true cost are on every plan, from $49 a month. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.