Baker's Percentage Explained: Why Flour Is Always 100%
August 19, 2026
You’ve found a bread formula that looks like this: flour 100%, water 65%, salt 2%, yeast 1%. Add it up and you get 168% — which, if percentages worked the way they did in school, would be impossible. There’s no ingredient list, no cup measurements, and apparently no way to know how much of anything to weigh out.
That table isn’t broken. It’s baker’s percentage — the notation professional bakeries have used for a century — and once you know the one rule behind it, it becomes the fastest way to read, compare, and scale any bread recipe on earth. Here’s how it works, why the total is supposed to blow past 100%, and the one question about it that reputable bakers still answer differently.
The one rule: everything is measured against the flour
In baker’s percentage, an ingredient’s number isn’t its share of the whole recipe. It’s its weight relative to the flour, and the flour is always, by definition, 100%. King Arthur Baking’s professional reference states it plainly: each ingredient is expressed as a percentage of the flour weight, and you get it by dividing the ingredient’s weight by the flour’s weight and multiplying by 100.
ingredient % = (ingredient weight ÷ flour weight) × 100
So “65% water” means: whatever your flour weighs, the water weighs 65% of that. With 500 g of flour, that’s 325 g of water. With 1,000 g, it’s 650 g. The percentage never changes; only the flour weight does.
And that’s why the total exceeds 100%. Flour alone already accounts for the full 100%, so everything added to it stacks on top — Wikipedia’s worked example is 10 lb of flour (100%) plus 5 lb of water (50%) totalling 150%. A formula summing to 168% isn’t an error; it’s a dough that weighs 1.68× its flour.
A worked example — the same numbers our calculator uses
Take the default formula in our baker’s percentage calculator: 500 g flour, 65% water, 2% salt, 1% yeast.
| Ingredient | Baker’s % | Weight |
|---|---|---|
| Flour | 100% | 500 g |
| Water | 65% | 325 g |
| Salt | 2% | 10 g |
| Yeast (instant) | 1% | 5 g |
| Total dough | 168% | 840 g |
Each row is just flour weight × percentage ÷ 100. That’s the entire
arithmetic — the calculator does it
live as you drag the sliders, in US or metric units, so you can watch 65%
water become 325 g without touching a calculator app.
Those defaults aren’t arbitrary. They sit inside the ranges the standard references publish: Wikipedia’s typical bread formula runs about 60% water, 2% salt and 1% yeast; Jeffrey Hamelman’s formulas in Bread use 2% salt as the standard; and Maurizio Leo of The Perfect Loaf gives 1.8–2.3% as the working salt range. Salt is the number to respect most — at 2% it’s only 10 g in an 840 g dough, but doubling it makes bread most people find inedible, and halving it makes fermentation race and flavour fall flat.
Why bakers bother: scaling becomes one number
The everyday payoff is scaling. Because every ingredient is chained to the flour, resizing a recipe means changing one number — the flour weight — and recomputing. No ratios to preserve by hand, no “1.5× of ¾ teaspoon” gymnastics.
Want the 840 g dough above as a 1,200 g dough for two loaves? Divide the target by the total percentage: 1,200 ÷ 1.68 = 714 g flour. Type that into the baker’s percentage calculator and every other weight follows: 464 g water, 14 g salt, 7 g yeast. For scaling a regular ingredient-list recipe (a stew, a cake) rather than a percentage formula, the recipe scaler is the better tool — but for bread, percentages are cleaner.
The second payoff is reading recipes at a glance. “65% hydration” tells an experienced baker how the dough will feel before touching it — hydration is simply the water percentage. King Arthur’s hydration guide calls their 63% Easiest Loaf a firm, “stiff” dough and their 100%-hydration Pan de Cristal “slack”; between those poles, standard sandwich loaves and pizza sit around 60–65%, most sourdoughs around 68–75%, and wet, open-crumbed styles like ciabatta from the high 70s up. Two recipes with wildly different yields become directly comparable the moment they’re written as percentages.
The part bakers disagree on: does starter flour count?
Here’s where it gets genuinely contentious. A sourdough starter (or any preferment — poolish, biga, levain) is itself made of flour and water. So when you compute your percentages, does that flour count toward the 100%?
The strict answer — the one Hamelman uses in Bread with his “overall formula” — is yes: all flour in the recipe is the 100% base, including what’s hidden inside the preferment. The pragmatic answer, which The Perfect Loaf often uses for small amounts of starter, is to treat the starter as a single ingredient and leave its flour and water out of the base for simplicity.
This isn’t a rounding quibble. Take a dough with 500 g flour, 10 g salt, and 100 g of 100%-hydration starter (50 g flour + 50 g water):
- Counting only the added flour: salt is 10 ÷ 500 = 2.0%
- Counting all flour, starter included: salt is 10 ÷ 550 = 1.8%
Same recipe, two different published numbers — and it’s exactly why you’ll see one source’s “2% salt” match another’s “1.8%”. The discrepancy grows with the amount of preferment: prefermented flour can run anywhere from a few percent to half the flour in the formula, and at the high end the two conventions describe noticeably different doughs. When you compare formulas from different authors, check which convention they’re using first.
Our baker’s percentage calculator takes the simple convention: the flour weight you enter is the 100% base. If you’re working with a levain, our sourdough calculator is built for exactly that case — it accounts for the flour and water inside the starter at whatever hydration you keep it.
Percentages need a scale, not cups
One caveat: baker’s percentage only works by weight. A cup of flour can weigh anywhere from about 120 g to 150 g depending on how it’s scooped, which would silently swing your “65% hydration” by several points. If your recipe is in cups, convert it to grams first — the cups to grams converter uses USDA and King Arthur densities per ingredient — and then work in percentages from there.
The one-line version
Flour is 100%, everything else is a fraction of the flour’s weight, and the total is supposed to exceed 100% — that’s the whole system. Master it and any bread formula becomes three numbers you can scale to any size with the baker’s percentage calculator.
From there, the specialised tools apply the same maths to specific doughs: the pizza dough calculator sizes dough balls by count and hydration, the sourdough calculator handles the starter question properly, and the yeast converter rescales that 1% when you’re swapping instant for active dry or fresh.