Bread Hydration Calculator

Hydration is water divided by flour, not by total weight

Bread hydration is one division: the weight of the water divided by the weight of the flour, written as a percentage. King Arthur Baking defines it the same way, as the total weight of water or water-bearing liquids divided by the total weight of flour. It is not the share of the dough that is water, and that mistake is the single most common reason a home baker's number does not match a recipe.

Take 500 g of flour and 350 g of water. The hydration is 350 / 500 = 70%, and the dough weighs 865 g once salt and yeast are added. If you divided 350 by 865 you would get 40.5%, which is the share of the dough that is water and tells you nothing about how the dough handles. Every recipe, every baker's formula and every calculator on this page uses flour as the base, because flour is the ingredient everything else is measured against.

The reason is practical. Flour is the thing you buy in a bag and build a recipe around, and water is the thing you adjust. When a dough feels tight, you add water in small amounts and watch the percentage climb. When it feels like soup, you add flour, and the percentage drops. A base of total dough weight would change every time you added either ingredient, which makes it useless as a reference point.

Liquids other than water count too. Milk, buttermilk, beer, tea, juice and even eggs are mostly water, and a recipe that uses them belongs in the numerator. This calculator adds water and other liquids together before dividing, which is why a dough made with 300 g of water and 50 g of milk sits at 70%, not 60%.

Worked example: 500 g flour and 350 g water

A country loaf: 500 g bread flour, 350 g water, 10 g salt, 5 g instant yeast. In baker's percentage, flour is always 100%, and everything else is measured against it.

The hydration is 70%, the salt is 2% of the flour, and the total is 173% of the flour weight. Those percentages are the whole recipe, and they scale: double every weight and the percentages do not move.

Now suppose you want 75% instead. The water needed is 500 x 0.75 = 375 g, so you add 25 g more than the recipe calls for. The dough becomes 890 g and the salt stays at 2%, because salt is measured against flour and the flour did not change. This is the part that trips people up when they adjust a recipe by feel: adding water raises hydration, adding flour lowers it, and adding either one changes the dough weight without touching the salt percentage.

Run the same math on a bigger batch. At 1,000 g of flour and 80% hydration, the water is 1,000 x 0.8 = 800 g and the dough is 1,800 g before salt. Same dough, twice the size, identical percentages. That is the entire value of baker's math: one set of percentages describes every batch size.

A wetter dough is not automatically a better one. King Arthur's own reference loaf sits at 63% and their pan de cristal sits at 100%, and both are correct for what they are trying to be. The number describes the dough, it does not rank it.

Reading baker's percentage

Baker's percentage is a ratio system, not a nutrition label. Flour is fixed at 100%, and every other ingredient is a percentage of the flour weight. Once you can read it, a recipe becomes a set of proportions you can scale, compare and adjust without opening a calculator.

• 100% is always the flour, or the total of the flours in a blend.
• Water above 100% is possible. A 110% dough has more water by weight than flour.
• Salt usually sits between 1.8% and 2.2%. Below 1.5% the bread tastes flat, above 2.5% it tastes salty and fermentation slows.
• Yeast runs from 0.2% for a slow cold ferment to 2% for a fast white loaf. Sourdough starter is usually 15% to 25% of the flour weight.
• Fat at 3% to 10% of flour weight softens the crumb, and it also counts as a liquid if it is butter or milk.

The total line is the sum of everything, and it tells you the dough weight before you mix. A 173% total on 500 g of flour is 865 g of dough, which fits a standard 9 by 5 inch loaf pan with a little room to rise. That is how professional bakers plan batch sizes: pick the dough weight the pan needs, then work backwards through the percentages.

One caution: a percentage is only as good as the scale. Volume measurements for flour vary by 10% or more depending on how the cup is filled, so a "70% hydration" dough made with cups can land anywhere from 64% to 78%. Weigh the flour and the water and the percentages become real. King Arthur's own baker's percentage reference makes the same point about weighing.

Why the same 70% behaves differently

Two bakers can mix 70% doughs and get completely different results, because flour absorbs water at different rates. Bread flour with 12% to 13% protein drinks more water than a soft southern all-purpose flour at 9% to 10%, so a 70% dough made with bread flour feels firm while the same 70% made with pastry flour feels sticky. The percentage is a ratio, not a promise.

Whole wheat makes it worse. Bran particles absorb water slowly and cut through gluten, so a 70% whole wheat dough behaves like a 60% white dough at first and like a 75% dough an hour later. Most whole wheat recipes add 5% to 10% extra water for that reason.

Typical ranges for common breads, which are conventions rather than rules:

King Arthur puts the firm end at 55% to 65% and the slack end at 75% to 85%, which matches the table. If your 72% dough feels like their 82% description, the flour is the difference, not your technique.

High hydration is not the same as soft

Social media made hydration a scoreboard, and the implication is that more water means better bread. It does not mean softer bread. Water changes the crumb structure, and structure is only one part of tenderness.

What high hydration does is open the crumb. More water, combined with good gluten development and a strong ferment, produces larger holes and a thinner crust. King Arthur's own write-up on whether wetter is better points out that the open crumb is the goal people are chasing, and that a medium hydration dough holds moisture well enough to stay soft for days.

Softness comes from three other things:

• Fat. Butter, oil, milk and eggs coat the starch and slow staling. A 60% milk bread with 8% butter is far softer than an 80% lean sourdough.
• Starch and gluten. A lower protein flour gives a finer, more tender crumb, which is why cake flour exists.
• Baking and storage. A loaf baked to 205 F and cooled before slicing keeps more moisture than one pulled early or cut hot.

There is also a cost to chasing water. Every 5% of hydration makes shaping harder, and a dough you cannot shape will not hold the gas that makes it light. A 75% dough shaped well beats an 85% dough shaped badly, every time. Pick the hydration your flour and your hands can handle, then work on fermentation.

Scaling a recipe with percentages

Once the recipe is in percentages, scaling is one multiplication. Decide the flour weight, multiply every percentage by it, and weigh. The table below gives water weights for the four hydrations most home bakers use.

Read it in both directions. If a recipe calls for 700 g of water and you want to bake 500 g of flour, the column tells you that is 70%. If you want a 75% dough from 1,000 g of flour, the row tells you 750 g of water.

Salt scales with flour, not with water. At 2% salt, 500 g of flour takes 10 g and 2,000 g takes 40 g, no matter the hydration. Yeast is the one ingredient that does not scale linearly with batch size in practice, because a bigger batch ferments faster from its own mass, so a 4 kg batch often needs slightly less yeast per kilo than a 500 g batch.

The most useful trick in the table is the middle column. Once you know your flour takes 70% comfortably, you can write your own recipes: pick 500 g of flour, add 350 g of water, 10 g of salt, 5 g of yeast, and you have a loaf. Everything else is a variation on that ratio.

Fixing a dough that is too wet or too dry

The calculator is most useful when a dough has already gone wrong. If the dough is sticky and spreading, you can add flour, but every gram of flour changes the ratio for everything else, so do the math before you pour.

Suppose you mixed 500 g of flour with 400 g of water, aiming for 75% but landing at 80%. To bring it back to 75% you need more flour: solve for the flour weight F where 400 / F = 0.75, which gives F = 533 g. You add 33 g of flour and the dough returns to 75%, but the salt percentage is now low, because the salt was measured against the original 500 g. At 2%, 500 g of flour took 10 g of salt; 533 g wants 10.7 g, so add 0.7 g of salt to keep the ratio.

The other direction is easier. A dough at 65% that you wanted at 70% needs water: 500 g of flour at 70% is 350 g of water, so if you started with 325 g you add 25 g. Add it in 10 g increments and mix between additions, because flour hydrates over 20 to 30 minutes and a dough that feels dry now may feel right after a rest.

Two habits prevent most of this. Hold back 5% of the water at the start and add it after the flour is fully wet, and write down the actual weights you used, not the ones in the recipe. A baking log with flour weight, water weight and room temperature is worth more than any hydration chart, because it records what your flour did in your kitchen.

What the percentage cannot tell you

Hydration is one number about one ratio, and a loaf depends on several things it does not measure.

• Flour absorption. Protein level, growing season and milling all change how much water a flour takes. The same brand can vary bag to bag.
• Fermentation. A 70% dough fermented for 18 hours in a cold kitchen behaves nothing like the same dough fermented for 3 hours warm.
• Technique. Folds, shaping tension and steam decide whether the water you added turns into an open crumb or a flat loaf.
• Environment. A dry winter kitchen pulls water from the surface of the dough, and high altitude changes how much liquid a dough needs.

The useful move is to treat the percentage as a starting point and your hands as the instrument. Mix to the number, then adjust by feel in small amounts, and record what you did. After three bakes you will know that your flour wants 72%, not 70%, and that is a better answer than any table can give you.

Sources for this page were checked on October 17, 2026. King Arthur Baking's hydration article and baker's percentage reference supplied the definitions and the 55% to 65% and 75% to 85% feel ranges, and their published recipes supplied the 63% and 100% examples. Flour protein and moisture figures vary by brand, so check the bag or the miller's spec sheet for the flour you use, and look up a specific flour in USDA FoodData Central if you want its published moisture and protein values.