What the notation means
In a baker's formula, flour is 100% and every other ingredient is written as a percentage of the flour weight. Not of the total — of the flour. So a formula reading flour 100%, water 70%, salt 2%, yeast 1% sums to 173%, and that is correct. With 500 g of flour it becomes 500 g flour, 350 g water, 10 g salt, 5 g yeast, and 865 g of dough.
The point of writing it this way is that the formula is now independent of batch size. Want three times as much? Multiply the flour by three and everything follows. Want to compare two bread recipes that came in different quantities? Convert both to percentages and the difference is immediately visible: this one is wetter, that one has twice the yeast. It is the reason every bakery formula and every serious bread book is written in percentages, and it only works because everything is measured by weight.
The ranges worth knowing
| Bread | Water | Salt | Yeast (instant) | Sugar | Fat |
|---|---|---|---|---|---|
| Baguette, lean bread | 68–75% | 2% | 0.3–1% | — | — |
| Sandwich loaf | 62–68% | 2% | 1–1.5% | 5–8% | butter 5–10% |
| Pizza dough, Neapolitan style | 58–65% | 2.5–3% | 0.1–0.5% | — | oil 0–3% |
| Ciabatta, focaccia | 75–85% | 2% | 0.4–0.8% | — | oil 0–5% |
| Bagel | 55–60% | 2% | 1% | 3–5% | — |
| Brioche | eggs 40–50%, milk 10–20% | 2% | 1.5–2% | 10–15% | butter 40–60% |
These are the working bands, not rules. Two things inside them are close to fixed. Salt sits at 1.8 to 2.2% almost universally, because below that fermentation runs away and the bread tastes of nothing, and above it the yeast slows measurably. And yeast trades directly against time: 1% instant yeast gives you a bulk ferment of an hour or two at room temperature, while 0.2% gives you an overnight one in the fridge and better flavour for the wait.
Hydration is not comparable across flours
70% in one kitchen is not 70% in another. Bread flour at 12–13% protein absorbs meaningfully more water than all-purpose at 10–11%, and whole wheat absorbs more still because the bran takes up water slowly over the first half hour. The same 70% formula can feel manageable with one flour and like batter with another.
The practical response is to hold back the last 5% of the water, mix, let it rest twenty minutes, and then decide. Adding water to a stiff dough is trivial. Getting water back out of a slack one means adding flour, which changes every other percentage in the formula and is how a carefully calculated bread turns into an approximate one.
Things that carry their own flour and water
A sourdough starter or a poolish is part flour and part water, and both parts belong in the totals. A 100% hydration levain is half flour and half water by weight, so 200 g of it contributes 100 g of flour and 100 g of water. Add those to the respective totals before working out the hydration, or the number you calculate will be lower than the dough you are actually holding.
The same applies to anything wet that is not called water. Milk is about 88% water, so 100 g of milk contributes roughly 88 g toward hydration. Eggs are about 75% water. Butter is about 16%. Formulas that use a lot of these — brioche, enriched sandwich breads — quote hydration in a way that is genuinely ambiguous unless the author says which convention they used, and the honest answer is to follow the recipe's own weights and not try to reverse-engineer a hydration figure from them.
Working backward from a dough weight
If you know what you want to end up with — say four 250 g pizza balls, so 1,000 g of dough plus a little for losses — divide the target dough weight by the sum of all the percentages expressed as a decimal. At 100% flour, 62% water, 2.5% salt and 0.3% yeast the sum is 164.8%, so 1,050 g of dough needs 1,050 ÷ 1.648, about 637 g of flour. Put that in the flour field and the rest of the formula falls out. Add 2% for what stays on the bowl and your hands; it is more than you think.
Questions people ask
Why do the percentages add up to more than 100?
Because flour is the reference, not the total. Setting flour to 100% and measuring everything against it is a deliberate choice: it makes the formula scale by a single multiplication and makes two recipes directly comparable no matter what quantities they were written in. A dough at 100% flour, 70% water, 2% salt and 1% yeast sums to 173%, and 173% is a perfectly meaningful number — it tells you the total dough weighs 1.73 times the flour weight, which is how you work backward from a target batch size.
What does 70% hydration actually mean?
Water weighing 70% of the flour weight. With 500 g of flour that is 350 g of water, giving 850 g before salt and yeast. It does not mean the dough is 70% water — by that measure it would be about 41%. And it is a weight ratio, not a volume one, which is why bread formulas are useless without a scale. 350 g of water is 350 mL, so the volume happens to be easy, but the flour side of it is exactly where cup measurement falls apart.
How much salt should bread have?
1.8 to 2.2% of the flour weight, which for 500 g of flour is 9 to 11 g. There is very little reason to leave that band. Salt does three jobs at once: it seasons, it tightens the gluten so the dough holds its shape, and it slows the yeast to a rate you can schedule around. Leave it out and the dough ferments fast, spreads, and tastes hollow. Go past about 2.5% and fermentation drags noticeably. Note that this is salt by weight, so the kosher salt brand question does not arise — weigh it and the crystal size stops mattering.
How do I convert between instant, active dry and fresh yeast?
Instant dry is the reference. Active dry is about 1.25 times the instant weight and wants dissolving in warm liquid first, though modern active dry generally works mixed straight in. Fresh or cake yeast is about three times the instant weight. So 5 g instant is about 6.25 g active dry or 15 g fresh. These are working conversions, not precise ones, and the tolerance is wide — yeast quantity trades against fermentation time, so being 20% off changes when the dough is ready rather than whether it works.
Can I put a sourdough starter into this?
Split it first. A starter at 100% hydration is half flour and half water by weight, so 200 g of starter is 100 g flour and 100 g water. Add those to the flour and water figures you enter here, and the hydration that comes out will be the true one for the dough. If your starter runs stiffer or wetter than 100%, split it by its own ratio instead. Skipping this step is the usual reason a calculated hydration reads lower than the dough feels.