Sourdough Hydration Calculator & Guide

What "hydration" actually means

Hydration in bread-making is a baker's percentage: the mass of water divided by the mass of flour, expressed as a percentage. Flour is always the reference (100%). If a formula lists 750 g flour and 525 g water, that's 70% hydration.

hydration % = (water g ÷ flour g) × 100

Accounting for the starter

A 100%-hydration levain is half flour, half water by weight. If your formula uses 150 g of starter, add 75 g to flour and 75 g to water before running the hydration calculation. Skipping this step is the most common reason home bakers hit a wall at around "72%" and cannot understand why the dough feels wetter than a published 78%.

Target ranges

• 65–70% — tight crumb, easy shaping. Good for beginners and sandwich loaves.
• 72–78% — classic country loaf. Open crumb without losing structure.
• 80–85% — high-hydration ciabatta / focaccia territory. Requires strong flour and confident handling.
• 90%+ — pan-formed only. Beyond the range of most home flours.

Worked example

Target: 900 g dough at 75% hydration, 2% salt, 20% starter (100% hydration).

total ratio = 100 (flour) + 75 (water) + 2 (salt) + 20 (starter) = 197 flour g = 900 × 100 / 197 ≈ 457 g water g = 900 × 75 / 197 ≈ 343 g salt g = 900 × 2 / 197 ≈ 9 g starter g = 900 × 20 / 197 ≈ 91 g

Skip the arithmetic

Our free hydration matrix does this live: type flour weight, target hydration, salt %, and starter %, and it returns every weight to the gram — plus a printable weigh sheet.