Bread Hydration Calculator
Turn a baker's percentage formula into weights: water, salt and leaven for any quantity of flour, with sourdough starter accounted for.
What you need
300g
Water to weigh out — Already reduced by the water your starter brings, where that applies.
- Flour to weigh out
- 450 g
- Salt
- 10 g
- Leaven
- 100 g
- Leaven in ounces
- 3.53 oz
- Total water in the dough
- 350 g
- Finished dough weight
- 860 g
What the hydration percentage refers to, starter included.
Guide figures. Ingredient weights, pan sizes and cooking times all vary — see the assumptions below for the ones used.
Shop this project
Working in percentages needs a scale; the rest is what handles a wet dough. Quantities come straight from your calculation above — check them against your supplier's pack sizes before ordering.
Your shopping list
- Bread flour
- 450 g
Materials
Bread flour
Higher protein absorbs more water, so the same hydration percentage feels stiffer than with all-purpose.
Instant yeast
Keeps for years in the freezer, which is cheaper than buying packets.
Tools & equipment
Digital kitchen scale
Weighing removes the cup-packing variable entirely, which is the single biggest accuracy win in baking.
Dutch oven
Traps the dough's own steam for the first half of the bake, which is what gives a home oven an open crumb.
Proofing basket
Supports a wet dough through its final rise instead of letting it spread.
Bench scraper
The tool that makes a high-hydration dough manageable by hand.
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How to use the bread hydration calculator
Bakers describe a dough as percentages of the flour weight — 70% hydration means 700 g of water to 1000 g of flour. Enter your flour weight and the percentages and this gives you the weights to put on the scale. If you are using a sourdough starter it carries its own flour and water, and that is subtracted properly rather than ignored.
Why bakers work in percentages
Because it makes a formula portable. A recipe in cups and spoons only works at the size it was written; the same dough in baker's percentages can be scaled to one loaf or fifty without a single recalculation, and two formulas can be compared at a glance to see which is wetter or saltier.
It also isolates the variable you are actually changing. If you want a more open crumb you raise hydration and leave everything else alone. In a cup-based recipe that same change is invisible, which is why troubleshooting bread from volume measurements is so frustrating.
Flour changes what a percentage feels like
Hydration describes the water, not the dough's handling. Whole wheat flour has bran that absorbs water slowly and greedily, so a 75% whole wheat dough feels stiffer than a 70% white one and keeps tightening as it rests. High-protein bread flour behaves similarly.
The practical approach is to hold back some of the water, mix, wait 20 minutes, and then decide whether to add the rest. The number tells you where you are aiming; the dough tells you whether that number was right for this particular bag of flour.
What this calculator assumes
Every estimate depends on figures that vary by supplier and conditions. These are the ones used here, so you can sanity-check the result against your own quote.
- Percentages are baker's percentages: every ingredient is expressed against total flour weight, and flour is therefore always 100%. This is why the numbers can exceed 100 in total.
- A sourdough starter is assumed to be 100% hydration — equal weights of flour and water, the standard for a stiff-ish white starter fed 1:1:1. Its flour and water are counted in the totals and deducted from what you add.
- If your starter is not 100% hydration the deduction will be slightly off. A wetter starter contributes more water and less flour; adjust the added water down accordingly.
- Hydration is a description, not a target to maximise. What a given percentage feels like depends heavily on the flour — whole wheat and high-protein bread flour absorb considerably more water than a soft all-purpose flour at the same number.
- Salt is calculated on flour weight, not on total dough weight. Recipes that quote salt against total weight will read about 40% lower for the same amount of salt.
- Finished dough weight excludes water lost to evaporation during baking, which is typically 10 to 15 percent for a free-standing loaf.
Frequently asked questions
What is baker's percentage?
A way of writing a dough formula where flour is always 100% and every other ingredient is a percentage of the flour weight. A 1000 g flour dough at 70% hydration and 2% salt needs 700 g water and 20 g salt. The advantage is that it scales to any batch size without recalculating anything, and lets two recipes be compared directly.
How much water do I need for 500g of flour?
It depends on the hydration you want. At 65% that is 325 g, at 70% it is 350 g, and at 75% it is 375 g. For a first sourdough, 70% is a sensible place to start — wet enough for an open crumb, dry enough to shape without a fight.
Does my sourdough starter count as flour and water?
Yes, and forgetting it is the most common error in sourdough maths. A 100 g starter at 100% hydration is 50 g flour and 50 g water. If you add your full flour and water on top of it, your dough is wetter and bigger than the formula intended. This calculator subtracts both halves for you.
What hydration should I use?
65 to 68% for sandwich loaves and anything you want to shape neatly. 70 to 75% for a typical open-crumb sourdough. 80% and above for ciabatta and focaccia, which are poured rather than shaped. Higher is not better — it is just a different bread, and a harder one to handle.
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