Sourdough Hydration Calculator
Set your flour weight, target hydration, and starter amount to get exact gram weights for flour, water, starter, and salt. Starter hydration is accounted for so your true hydration is always accurate. Nothing uploaded.
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Learn more: baker's percentages and true hydration
The problem with most hydration calculators
Search for a sourdough hydration calculator and you will find dozens of simple tools that divide water by flour and call it done. But your starter is not water - it is a mixture of flour and water with its own hydration ratio. A 20% starter addition at 100% hydration adds around 50g of hidden water to a 500g loaf, shifting your true hydration by almost 5 percentage points. This calculator tracks the flour and water in your starter separately, so the hydration reading matches what your dough actually feels like.
How to use the sourdough hydration calculator
First, enter your flour weight or total dough weight by toggling between starting from flour weight (e.g. 500g) or a desired total dough weight (e.g. 900g). Second, set target hydration by dragging the slider from 60% to 95% or typing a value - most recipes sit between 70% and 80%. Third, add starter amount as a percentage of flour (typically 15-20%) and your starter's hydration (100% for a 1:1 starter), plus salt percentage (usually 2%). Finally, read the gram weights - the calculator shows flour, water to add, starter, and salt in grams with true hydration accounting for water already in your starter.
FAQ
What is baker's percentage in sourdough?
Baker's percentage expresses every ingredient as a share of the total flour weight. Flour is always 100%. If you use 500g flour and 375g water, your hydration is 75%. This system makes it easy to scale recipes up or down without recalculating ratios.
What is true hydration in sourdough and why does it matter?
True hydration accounts for the flour and water already in your starter. A 100g addition of 100% hydration starter (50g flour + 50g water) adds water to your dough that is not in your main water measurement. True hydration gives you the actual water-to-flour ratio across the whole dough.
What hydration is best for beginners?
Most beginners do well at 70-75% hydration. The dough is manageable without being too wet and sticky. Higher hydrations (80-90%) give an open crumb but require stronger technique. Start at 70%, master the fold and ferment, then increase gradually.