Baker's Percentages Explained: Hydration, Salt, and Yeast

Published 2026-05-19 · By the CalculatorHive editorial team

Open any professional bread book and the recipes look like spreadsheets: flour 100%, water 72%, salt 2%, starter 20%. That notation is baker's percentage, and once you can read it you can compare any two formulas at a glance, scale a recipe to any batch size, and diagnose a dough that came out wrong. This guide covers how the notation works, what the numbers mean for handling and crumb, how a starter or preferment complicates the arithmetic, and how to scale to an exact dough weight.

What is baker's percentage?

Every ingredient is expressed as a percentage of the total flour weight, which is always defined as 100%. If a formula uses 1,000 g of flour and 700 g of water, the hydration is 70%. If it uses 20 g of salt, that is 2%. If it uses 10 g of yeast, that is 1%.

Because flour is the denominator rather than the total, the percentages add up to more than 100 — 173% in that example. That is not an error; it is the whole point. The system is a ratio notation, not a share-of-total notation, and it means the numbers stay identical whether you are making one loaf or two hundred.

Two rules keep it consistent. First, work in weight, never volume — grams for anything under a few kilograms. Second, when a formula uses more than one flour, they still sum to 100% between them: 80% bread flour plus 20% whole wheat, not 100% plus 25%.

What hydration should I use?

Hydration is the single number that most determines how a dough behaves. Low-hydration doughs are stiff, easy to shape, and produce a tight, even crumb. High-hydration doughs are slack and sticky, hold more steam during the bake, and produce the open, irregular crumb people chase in artisan loaves — at the cost of being much harder to handle.

These ranges assume a strong white flour. Two things shift them. Whole grain flours absorb noticeably more water than white, so a 75% whole wheat dough handles more like a 65% white dough — recipes with significant whole grain usually need hydration pushed up, and benefit from an autolyse or soaker to let the bran hydrate before mixing. Protein content matters too: a 12.7% protein bread flour will take more water than a 10.5% all-purpose flour and still hold its shape.

If you are new to high hydration, do not jump straight from 65% to 80%. Move up in 3–5% steps and learn the handling at each level. The sourdough hydration calculator will convert between a target hydration and the actual water weight for your flour.

How does a sourdough starter change the maths?

This is where most home bakers' percentages quietly go wrong. A starter is not an ingredient in its own right — it is flour and water that have already been mixed. Both parts must be added to the totals before you compute hydration.

A starter maintained at 100% hydration (fed equal weights of flour and water) is exactly half flour, half water. So 200 g of that starter contributes 100 g of flour and 100 g of water. A stiff starter at 50% hydration is two parts flour to one part water: 150 g contributes 100 g flour and 50 g water.

Worked example. You want a loaf with 500 g total flour at 75% hydration, using 100 g of 100% hydration starter, salt at 2%.

1. Starter contributes 50 g flour and 50 g water.
2. Total water needed = 75% × 500 = 375 g. Water already present in the starter = 50 g, so add 325 g.
3. Flour to add = 500 − 50 = 450 g.
4. Salt = 2% × 500 = 10 g.
5. Total dough = 500 + 375 + 10 = 885 g.

Check the result: total water 375 ÷ total flour 500 = 0.75, so the dough really is at 75%. Had you ignored the starter and simply used 375 g of added water with 500 g of added flour plus the starter, you would have ended up at 425 g water against 550 g flour — 77.3% — and a wetter dough than intended. The error is small on one loaf and compounding on a large batch.

The same logic applies to any preferment: poolish (usually 100% hydration), biga (typically 50–60%), or pâte fermentée (a piece of yesterday's dough, carrying salt and yeast as well as flour and water, all of which should be counted).

How much salt and yeast?

Salt is remarkably consistent across bread formulas: 1.8–2.2% of flour weight, with 2% the default. It is not only for flavour — salt tightens the gluten network, slows fermentation, and improves crust colour. Below about 1.5% bread tastes noticeably flat and the dough ferments faster than expected; above about 2.5% it tastes salty and fermentation drags. Note that salt is measured by weight, so the type does not matter to the percentage even though a teaspoon of fine table salt weighs far more than a teaspoon of flaky salt. This is another argument for the scale.

Yeast varies with how long you want the fermentation to run. A same-day dough might use 1–2% instant yeast; a dough intended for an overnight cold retard might use 0.2–0.5%; a long, slow pizza dough can go below 0.1%. Less yeast and more time generally produces better flavour, because fermentation by-products accumulate over hours rather than minutes.

Active dry yeast has a proportion of dead cells acting as a protective coating, which is why more is needed; traditionally it is rehydrated in warm water first, though most modern brands tolerate being mixed straight in. Instant yeast has finer granules and goes directly into the flour. The yeast converter handles substitutions in either direction.

How do I scale a formula to a target dough weight?

This is the calculation that makes baker's percentage worth learning. You know how much dough you want — three 800 g loaves, or six 250 g pizza balls — and you need the ingredient weights.

Add up all the percentages to get a total, then divide your target dough weight by that total (as a decimal). The result is the flour weight; every other ingredient follows from its own percentage.

Worked example. Target 1,000 g of dough, formula at 100% flour / 70% water / 2% salt / 1% yeast = 173% total.

• Flour = 1,000 ÷ 1.73 = 578 g
• Water = 70% × 578 = 405 g
• Salt = 2% × 578 = 12 g
• Yeast = 1% × 578 = 6 g
• Total: 578 + 405 + 12 + 6 = 1,001 g (rounding)

For pizza, work backwards from the ball weight instead: six 250 g balls is 1,500 g of dough, so flour = 1,500 ÷ 1.73 = 867 g. Add 2–3% for what sticks to the bowl and your hands if you need the finished weights to be exact. The pizza dough calculator does this from ball count and ball weight directly, and the recipe scaler handles the more general case of multiplying any recipe up or down.

Common questions

Do eggs, milk, butter and oil count in the percentages?

They are all expressed as percentages of flour like anything else — butter at 10%, eggs at 20%, and so on. Whether they count toward hydration is a separate question and a matter of convention. Strictly, hydration means water, but many bakers count milk as roughly 87–90% water and eggs as roughly 75% water when working with enriched doughs, because those liquids really do hydrate the flour. The important thing is to be consistent so your own formulas remain comparable.

Why does my dough feel wetter than the same percentage did last time?

Flour is not standardised. Protein content, milling, and how much moisture the flour has absorbed from the air all change how much water it takes before the dough feels slack. The same 72% formula can feel entirely different with a new bag or in a humid month. Hold back 20–30 g of the water at mixing and add it once you have felt the dough — that is standard practice in bakeries, not a sign you are doing it wrong.

Can I convert a cup-based recipe into baker's percentages?

Yes, but not accurately from the cup measurements alone, because a cup of flour varies by 20% or more depending on how it was filled. Make the recipe once while weighing each ingredient as you add it, record the grams, then divide everything by the flour weight. From that point on you have a real formula you can scale reliably.

What total percentage should I expect for a normal bread formula?

Around 170–180% for a lean dough — 100 flour, 65–78 water, 2 salt, plus a little yeast. Enriched doughs with eggs, butter, sugar and milk climb to 200% or beyond. If your total is under about 155%, the dough is very stiff and probably a bagel, cracker, or pasta formula.