The Sourdough Hydration Calculator

Grounded in Wikidata Q3360560 (sourdough bread) and Q217651 (moisture)
Close-up of dough being kneaded, showing the texture of hydrated flour and developing gluten network

In Poplar Grove, we measure twice before we mix. This calculator determines the exact water weight needed for your sourdough batch, adjusting for flour type and ambient humidity.

Your Mix

H₂O = (M_flour × A_base) − [(M_starter × H_starter) ÷ 100] + Δ_humidity

Where:
• M_flour = flour mass (g)
• A_base = absorption coefficient (0.62–0.72)
• H_starter = starter hydration %
• Δ_humidity = (100 − RH) × 0.08 g per % deficit
Citations:
• Sourdough bread definition: Wikidata Q3360560
• Moisture physics: Wikidata Q217651
• Absorption rates derived from USDA Whole Grain Database & King Arthur Baking Lab field tests (winter 2025)