Why flour gets to be 100
Baker's percentages look strange the first time: the percentages add up to more than 100. That is because they are not shares of the dough. They are shares of the flour, and flour is the one ingredient every bread formula is built around.
Write a dough as 100 : 70 : 2 : 1 and you have said something a list of grams cannot. You have said the hydration, the salt level and the yeast level in a form that survives scaling. The 500 g version and the 5 kg version of that formula are the same bread.
Cup measures cannot do this. Two bakers measuring "3 cups of flour" can differ by 15 percent, and every percentage built on top of that error moves with it. Weighing is what makes the system work, which is why the cups to grams page exists.
The formula
Each ingredient's percentage is its weight divided by the total flour weight, times 100. When a formula uses more than one flour, the flours are added together first and the sum is the 100.
| Quantity | Formula | 500 g flour example |
|---|---|---|
| Ingredient % | ingredient g / flour g x 100 | 350 / 500 x 100 = 70% |
| Scaling factor | target flour / formula flour | 1,000 / 500 = 2 |
| Scaled ingredient | formula grams x factor | 350 x 2 = 700 g |
The calculator above does both directions in practice: read the percentages off the table, or enter a target flour weight and multiply each line by the factor. There is no second formula to learn.
What the bands mean, and where hydration fits
Baker's percentage is the vocabulary the hydration bands are written in. A "70 percent dough" is a statement about the water line only, and it is only honest if the starter, if there is one, has been counted. That counting is exactly what the sourdough hydration calculator does, and the feeding side is handled by the starter feeding calculator.
| Line in the formula | Usual range | What moving it does |
|---|---|---|
| Water | 60 to 80 | Wetter doughs bake open crumb but fight back when shaping |
| Salt | 1.8 to 2.3 | Controls taste and tightens gluten; too much slows yeast |
| Yeast, instant | 0.5 to 1.5 | Long cold ferments use the low end |
| Sourdough starter | 10 to 50 | More starter ferments faster and tastes tangier sooner |
| Fat, oil and butter | 0 to 15 | Tenderises crumb and softens crust |
These ranges are conventions from published bread formulas rather than fixed rules, and the sources below state them as ranges for that reason.
Scaling a formula to any flour weight
The scaling factor is the target flour weight divided by the formula's flour weight. Multiply every line, not just the ones you remember.
| Ingredient | Formula, 500 g flour | x 2, 1,000 g flour |
|---|---|---|
| Flour | 500 g | 1,000 g |
| Water, 70% | 350 g | 700 g |
| Salt, 2% | 10 g | 20 g |
| Yeast, 1% | 5 g | 10 g |
| Total | 865 g | 1,730 g |
One caution: fermentation time does not scale. A doubled batch in the same bowl ferments at nearly the same speed, so do not double the clock. The general mechanics of rescaling any recipe, not just bread, are on the recipe scaling guide.
Questions bakers actually ask
- Why do my percentages add up to more than 100?
- Because they are measured against the flour, not against the whole dough. Flour is 100 by definition and everything else is relative to it. A 100 : 70 : 2 formula is 172 percent of dough weight and is written correctly.
- How do I use baker's percentage with a sourdough starter?
- Weigh the starter and put it on its own line, usually 10 to 50 percent of the flour. For the honest hydration figure, split the starter into its flour and water first, which the hydration calculator does for you.
- What if my formula uses two flours?
- Add them. A 400 g white and 100 g whole wheat formula has 500 g total flour, so both percentages are measured against 500. The calculator's add-ingredient rows handle this: enter each flour as its own row and the tool sums them as the denominator.
- Can I convert a volume recipe into percentages?
- Only after converting it to weight, because percentages of cups are meaningless. Convert each ingredient with the cups to grams tool, then enter the gram weights here.
- Is 2% salt mandatory?
- No. Published formulas sit between 1.8 and 2.3 percent, and long cold proofs often want the top of that range. The percentage system exists precisely so you can move the line and see what you did.
Where these numbers come from
The formulas are arithmetic and carry no measurement error. The working ranges are quoted from published bread references rather than averaged into a house opinion, and each is linked below.