Calcylator
Baking

Dough hydration:
water ÷ flour × 100

Turn a hydration target into grams of water, learn what high and low hydration do to a loaf, and avoid the usual weighing slips.

Calcylator Editorial Team

Updated · 5 min read

What dough hydration means

Dough hydration is the weight of water as a percentage of the weight of flour. If you mix 375 g of water with 500 g of flour, the hydration is 75%. Both weights are in grams, and the water is always compared with the flour, not with the whole dough.

Bakers use it because it describes the feel of a dough in one number. A higher figure means a wetter, stickier dough, and a lower figure means a stiffer one. Two recipes of completely different sizes can share the same hydration, so you can compare them at a glance.

The hydration formula and a worked example

Hydration =hydration % = water ÷ flour × 100
water:
weight of water in grams
flour:
total weight of flour in grams, which must be above zero
To find the water you need, rearrange it: water = flour × hydration ÷ 100.

  • Water

    375 g

  • Flour

    500 g

  • Division

    375 ÷ 500 × 100

Hydration

75%

The Calcylator dough hydration calculator shows one decimal place, so 75 appears as 75.0%.

How much water for a target hydration

Work backwards when a recipe gives you a percentage. For 600 g of flour at 70%, multiply 600 × 0.70 to get 420 g of water. Because 1 ml of water weighs about 1 g, you can measure 420 ml if you have no scale for liquids.

As a rough guide, many sandwich-style loaves sit in the low 60s, a lot of home sourdough loaves are made in the 70s, and very open, airy doughs such as ciabatta go higher. Treat these as starting points rather than rules, since recipes vary.

Water needed for 500 g of flour
HydrationWater
60%300 g
65%325 g
70%350 g
75%375 g
80%400 g

What changes when you add or remove water

Higher hydration generally gives a softer crumb with bigger holes, but the dough is harder to shape and tends to spread. Lower hydration is easier to knead and handle, and suits things like bagels and some flatbreads, but the crumb is tighter.

Flour matters as much as the number. Wholemeal flour usually soaks up more water than white flour, so 70% hydration can feel quite different from one bag of flour to another. If a dough is too slack, hold back a little water next time and adjust in small steps.

A starter adds both flour and water too. If you want an exact percentage, count the flour and water inside the starter in your totals, using the weights you actually put in.

Hydration in real kitchens

A home baker making a weekend loaf, a pizzeria preparing dough for the evening rush and a café baking sandwich bread all rely on the same arithmetic. The difference is scale: the pizzeria might mix several kilograms of flour at a time, and the percentage keeps every batch consistent from one day to the next.

If a recipe calls for a different amount of flour than you have, keep the hydration and scale the water. With 800 g of flour at 70%, the water is 800 × 0.70 = 560 g. The dough should behave like the original, give or take small differences caused by the flour or the weather in your kitchen.

Common hydration mistakes

  • Using cups instead of grams. A cup of flour can vary a lot in weight.
  • Dividing water by the total dough weight instead of by the flour.
  • Forgetting that milk, eggs and oil also contribute liquid.
  • Treating the percentage as a pass or fail. It describes a dough, it does not grade it.
  • Changing flour brand and keeping the same water.

Common questions

How do I calculate dough hydration?

Divide the weight of water by the weight of flour and multiply by 100. For 375 g of water and 500 g of flour, 375 ÷ 500 × 100 gives a hydration of 75 percent. Use grams for both.

How much water do I need for 500 g of flour?

It depends on the hydration you want. At 65 percent you need 325 g, at 70 percent 350 g, and at 75 percent 375 g. Multiply the flour weight by the percentage as a decimal.

What is a good hydration for bread?

There is no single best figure. Sandwich-style loaves are often made in the low 60s, many home sourdough loaves in the 70s, and open crumb breads higher. Start near the recipe and adjust to your flour.

Does 1 ml of water equal 1 gram?

Yes, for practical baking, 1 ml of water weighs very close to 1 gram. So 350 g of water is about 350 ml. Weighing is still more accurate than a measuring jug, especially for small amounts.

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