Bread hydration calculator: find your dough's ideal water level

How It Works

How bread hydration actually scales

Hydration in bread and pizza dough is always calculated as a percentage of the flour weight, not the total dough weight. This is the baker's percentage system, and it's what lets you scale any recipe up or down while keeping the exact same ratios intact. If a recipe reads 75% hydration, that means 75g of water for every 100g of flour, whether you're making a single 500g test loaf or a 5kg batch for a Saturday market stall. The sourdough hydration calculator on this page runs that same formula: enter your flour weight and your current or target hydration, and it works out the water weight either way, then tells you exactly how much to add or take away to move from one to the other.

What that percentage actually feels like in your hands depends on more than the number on the screen, though. Flour protein content sets how much water the gluten network can hold onto: strong bread flour at 13 to 14% protein will happily take on 75 to 85% hydration and still form a workable dough, while a softer all-purpose flour at 10 to 11% protein starts turning to soup well before that point. Flour age and ambient humidity shift things too, since flour that's been sitting out in a warm kitchen absorbs less water than fresh flour from a cool pantry, so the same 75% can feel noticeably wetter on a humid summer afternoon than it did in the depths of winter. And if you're feeding a sourdough starter into the mix, it's not just flavour and lift it's bringing: the starter is itself a flour-and-water mixture, and its own hydration counts towards your dough's final total. A 100%-hydration starter added at 20% of total flour weight adds a meaningful chunk of extra water that's easy to miss when you're totting up your final percentage by hand.

It's worth being clear about what hydration percentage does and doesn't tell you. Two doughs at exactly 75% hydration, one made with a soft all-purpose flour and one made with a strong Canadian bread flour, will feel completely different in the bowl even though the maths behind them is identical. The percentage describes a ratio, not a texture. That's precisely why the calculator asks for flour type alongside your flour weight rather than just returning a single generic water figure: the target range it suggests already accounts for how that particular flour is likely to absorb water, so you're not left guessing whether 75% is ambitious or conservative for what's actually in your bag.

How hydration changes fermentation and proofing time

Hydration doesn't just change how dough feels in your hands, it changes how fast it ferments. Wetter doughs give enzymes and yeast more room to move, so chemical reactions happen faster and gas bubbles expand more freely through the looser gluten structure. Push hydration from 65% to 80% on the same recipe, same flour, same starter or yeast quantity, same room temperature, and you'll typically see bulk fermentation finish sooner, not because there's more yeast activity but because the dough itself offers less resistance to the gas being produced. This is one of the reasons a recipe copied exactly from someone else's blog can behave differently in your kitchen: if your hydration ends up even a few percent different from theirs, whether through a different flour's absorption rate or a slightly generous cup measurement, your fermentation timeline will drift too.

The practical takeaway is to treat hydration and fermentation time as linked variables rather than separate ones. If you push your hydration up from a recipe's stated percentage, expect bulk fermentation to run somewhat faster and keep a closer eye on the dough rather than the clock. If you're baking in a notably warmer or cooler kitchen than the recipe was written in, the interaction between hydration and temperature compounds further, since both independently speed up or slow down fermentation. The fermentation calculator and the dough temperature calculator both work alongside this one; hydration sets your target water weight, temperature and fermentation timing tell you how long to leave it once mixed.

How the hydration calculator handles different flour types

Not all flour absorbs water the same way, which is why the calculator on this page asks for your flour type rather than just a single flour weight. White bread flour, wholemeal, rye, spelt and einkorn each have a different absorption profile driven by protein content, bran percentage, and starch structure, and the calculator's suggested hydration range shifts accordingly. Wholemeal and rye in particular need more water than white flour to reach the same dough consistency, because bran fragments soak up moisture that would otherwise be available to hydrate the gluten-forming proteins. Miss this adjustment and a straight wholemeal substitution into a white-flour recipe, using the white flour's hydration percentage unchanged, produces a noticeably drier, tighter dough than intended.

Blended flours split the difference. If your recipe calls for 80% white flour and 20% wholemeal, the calculator's guidance sits closer to the white flour end of the range but nudges upward slightly to account for the wholegrain portion, roughly in line with the "+5% per 20% wholegrain" rule of thumb used throughout this page. The same logic applies to rye, though rye behaves a little differently again because its lower gluten content means the extra water goes more towards workability and crumb texture than towards classic gluten development.

Common hydration mistakes

Hydration by bread type: a reference table

There's no single "correct" hydration for bread. What's correct depends entirely on what you're making. A bagel and a ciabatta are both wheat dough, flour, water, yeast or leaven, salt, yet they sit at almost opposite ends of the hydration scale because they're built to do completely different jobs. A bagel needs to be dense and chewy enough to hold its shape through boiling and baking. A ciabatta needs to be slack and wet enough to collapse into big, irregular holes. Use the table below as a starting point for whatever you're baking, then fine-tune with the calculator once you know your flour's absorption.

Ranges assume a strong bread flour (12–13% protein). Softer flours will sit at the lower end of each range or need less water overall.

Preferments and hydration: poolish, biga and sourdough starter compared

A preferment is a small portion of a recipe's flour and water, fermented ahead of the main mix, and every preferment carries its own hydration that has to be folded into your final dough calculation. Poolish, biga and sourdough starter are the three you'll meet most often, and they behave differently because they're built at different hydrations for different reasons. Miss this step and your "70% hydration" recipe can quietly turn into something wetter or drier than you intended, depending on which preferment you're using and how much of it goes in.

Whichever preferment you use, add its flour and water into your recipe's totals before calculating overall hydration, the same rule that applies to a sourdough starter.

Hidden water in enriched doughs: eggs, milk and butter

Lean bread doughs (flour, water, salt, yeast or starter) are straightforward to calculate because water is the only source of hydration. Enriched doughs, brioche, milk buns, panettone, are a different story. Eggs, milk and butter all contain a meaningful proportion of water, and that water counts towards your dough's total hydration whether you account for it or not. Ignore it and two recipes that look similar on paper, one lean, one enriched, can behave very differently in your hands because the enriched one is actually wetter than its written percentage suggests.

These are approximate averages for standard UK dairy and egg products. Use them to estimate hidden water when converting a lean formula to an enriched one, or when comparing two enriched recipes.

Cups to grams: a working conversion table

Hydration only means anything when it's measured by weight. A cup of flour can vary by 20 to 30g depending on how it's scooped, which is more than enough to shift a recipe from 70% to 75% hydration without anyone touching the water. If you're working from an American recipe written in cups, convert everything to grams first, then run the numbers.

For the full 50+ ingredient database with cups, tablespoons and ounces, use the ingredient converter calculator. Always weigh on a digital scale where possible; cup conversions are a fallback, not a first choice.