Bread Flour Conversion Calculator

Bread hydration is the ratio of water to flour in a dough, expressed as a percentage. It is the single most important variable in bread baking. It sets the crumb structure, the crust texture, and how sticky the dough is to handle.

The Formula:

Hydration (%) = (Water weight / Flour weight) × 100

Rearranged to give the water:

Water (g) = (Hydration % / 100) × Flour weight (g)

Swapping one flour for another is a 1:1 exchange by weight, never by volume. What changes is how much water that same weight wants, because protein and bran both drink more than white starch does.

Hydration Reference Guide:

Water Adjustments Used Here:

The reverse swaps take the same numbers with the sign flipped, so bread flour back to all-purpose is minus 2.5%. The three are consistent with each other: going all-purpose to whole wheat by way of bread flour adds 2.5 plus 5, which is the 7.5 in the table.

Worked Example:

A recipe calls for 500 g bread flour at 72% hydration.

Water = (72 / 100) × 500 = 360 grams

Now swap all 500 g for whole wheat. Bran drinks more, so add 5% of the flour weight:

500 × 0.05 = 25 g, giving 385 grams of water, which is 77% hydration.

Swapping only part of the flour scales the same way. Replace a fifth of it and you add a fifth of the correction, 5 g rather than 25.

Practical Tips:

• Always weigh flour and water. Volume measurements are unreliable for hydration
• High-protein bread flour (12 to 14% protein) handles higher hydration better than all-purpose
• Add water in stages when making high-hydration dough. Hold back 5 to 10% until you feel the texture
• Autolyse (resting flour and water 20 to 30 min before adding yeast) improves extensibility at any hydration level
• Humidity and flour age both move absorption around, so dough feel matters as much as the numbers