Bread Hydration: Calculate Water and Understand the Limits

Calculate the simple version

For a lean flour-and-water dough, divide water weight by total flour weight and multiply by 100. With 350 g water and 500 g flour, hydration is 70%. With 650 g flour at a target of 68%, water is 650 × 0.68 = 442 g.

Use weights in the same unit. A cup of flour and a cup of water do not weigh the same amount, so dividing their volumes will not produce the same ratio. A scale makes both the calculation and the next batch easier to reproduce.

Compare like with like

Two doughs at 70% can handle differently because their flours, milling, additions and processing differ. A number alone cannot tell you whether to add a handful of flour or whether the dough is ready for shaping. Compare formulas with their full ingredients and methods beside them.

Milk, eggs and syrups contain components beyond water. Treating their complete weight as pure water can give a misleading comparison. The calculator on this site is for a lean flour-water-salt-yeast formula; it deliberately does not claim to calculate the true water content of an enriched dough.

Use a small controlled change

Start with a reliable recipe that already works in your kitchen. If you choose to compare hydration, keep flour, batch size and method as similar as practical. For 500 g flour, a two-percentage-point change is 10 g water, not 2 g.

Record the original and changed formula, dough temperature if available and how the dough behaves during mixing and shaping. Label the experiment as an adaptation. Do not describe an untested hydration change as a guaranteed improvement; your result depends on ingredients and technique as well as the arithmetic.

Read a hydration change in grams

Begin with 600 g flour and 390 g water. The hydration is 65%. Moving to 67% would require 600 × 0.67 = 402 g water, a difference of 12 g. Moving to 70% would require 420 g, a difference of 30 g. Writing those differences in grams makes the size of the experiment easier to understand.

If your formula includes a starter, calculate total flour and water before making that comparison. For example, adding an uncounted 100 g starter changes the denominator as well as the water total. A seemingly small arithmetic omission can therefore mislabel the entire dough.

During a practical comparison, note what you had to change to handle the dough. If you added flour during shaping without recording it, the final formula is no longer the planned one. That does not make the loaf worthless, but it limits what you can conclude about the chosen hydration. Record the adaptation honestly and repeat the experiment more carefully if the question still matters. A useful note describes both the intended ratio and what actually happened at the bench.

Questions that come up