Sourdough Hydration Calculator
Work out your dough's hydration in seconds. Updates live as you type.
How to use this calculator
Enter your flour, water, and starter weights in grams. The total hydration updates instantly, including the water and flour contained in your starter. Most home sourdough recipes sit between 65% and 80% total hydration — lower values are easier to shape, higher values produce more open crumb.
Need to get your starter ready first? Our starter feeding calculator tells you exactly how much flour and water to add for any ratio.
Understanding the math
Baker's math treats flour as 100% and expresses everything else as a percentage of that flour weight. Hydration is just the water percentage. The tricky part is that your starter contains both flour and water, so you can't just divide the water in your recipe by the flour in your recipe — you have to add the starter's contribution to both sides.
A 100% hydration starter is equal parts flour and water by weight. So 100g of starter = 50g flour + 50g water. This calculator breaks that out for you automatically based on whatever starter hydration you enter.
What hydration levels mean in practice
60-65% — stiff dough, easy to shape, tight crumb. Good for sandwich loaves, bagels, and pizza.
65-70% — the beginner-friendly sweet spot. Holds shape well while still producing recognizable sourdough character.
70-78% — classic artisan loaf territory. Needs technique for shaping but gives you an open, airy crumb.
78-85%+ — ciabatta and focaccia territory. The dough is essentially a wet batter; shape with wet hands or dough scrapers only.
Frequently asked questions
What is baker's percentage?
Baker's percentage expresses each ingredient as a percentage of the total flour weight. Flour is always 100%, and water, starter, and salt are stated as percentages of that flour. It makes recipes portable — you can scale them up or down to any loaf count while keeping the ratios correct.
What hydration should I use for my first sourdough?
Start at 65-70% hydration. It produces a dough that is forgiving to handle while still giving good crumb. Move higher (75-85%) once you're comfortable with shaping.
Does starter hydration affect my final dough hydration?
Yes. The water and flour in your starter count toward the total. A 100% hydration starter is half water by weight. This calculator accounts for that automatically.
Why does my dough hydration calculation look different from recipes I find online?
Many recipes state hydration without including the starter's contribution. This calculator shows true total hydration, which is the number that actually determines dough feel and behavior.
How much salt should I use?
2% of total flour weight is the standard. Lower than 1.5% makes bread taste flat; higher than 2.5% suppresses fermentation. For 500g of flour, use 10g of salt.