A sourdough hydration calculator uses baker's percentages to give you exact gram weights for flour, water, starter, and salt. Baker's math accounts for the flour and water already in your starter so total hydration is accurate across different starter hydrations.
Dough Parameters
900g makes one standard 750g loaf
Baker's Formula
How to Use the Sourdough Hydration Calculator
Baker's percentage is the language of professional baking — and understanding it is the key to adjusting any sourdough hydration recipe. This calculator converts percentages to gram weights, accounting for the flour and water already in your starter so your total hydration is accurate.
Step 1: Set your target dough weight
Enter how much total dough you want to make. A standard 750g loaf requires about 850-950g of dough before baking, accounting for oven spring and moisture loss. For two loaves, multiply by two. Toggle between grams and ounces using the unit buttons.
Step 2: Set target hydration
Use the slider to set your target dough hydration. Beginners: start at 65-72%. Intermediate bakers: 72-80%. Advanced: 80-90%+. Higher hydration creates a more open, airy crumb but requires more skill to handle. The bread type also matters — ciabatta is 80%+, country loaves are 70-78%, and stiff bagels are 55-65%.
Step 3: Set starter amount and hydration
The starter percentage slider sets how much starter to use relative to total flour. Higher percentages mean faster fermentation. The starter hydration slider should match your actual starter — if you feed equal weights of flour and water, it is 100% hydration. If you feed 1 part flour to 0.8 parts water, it is 80% hydration.
Step 4: Read the formula
The results show total flour and water (including what is in the starter) plus the extra flour and water to add separately. Combine extra flour and extra water first, then add starter, then add salt after the autolyse. This ensures optimal gluten development before introducing the salt's tightening effect.
Frequently Asked Questions
Is this sourdough hydration calculator really free?
Yes, completely free with no account required. All calculations happen in your browser — nothing is sent to any server.
What is baker's percentage in sourdough baking?
Baker's percentage expresses all ingredients as a percentage of the total flour weight. Flour is always 100%. If hydration is 75%, that means 75g of water for every 100g of flour. This system makes it easy to scale recipes up or down and compare recipes regardless of batch size.
What hydration level is best for beginners?
Beginners should start with 65-72% hydration. Lower hydration dough is firmer, easier to shape, and more forgiving. Higher hydration doughs (80%+) are more extensible, produce an open crumb, but are much harder to handle. Master lower hydrations before working up to high-hydration loaves.
How does starter hydration affect the calculation?
Your sourdough starter contains both flour and water. A 100% hydration starter has equal parts flour and water by weight. When calculating total recipe flour and water, you must account for the flour and water already in your starter — this calculator does that automatically.
What percentage of starter should I use?
Typical recipes use 15-25% starter (relative to flour weight). Higher percentages (25-30%) speed fermentation and work well in cooler environments. Lower percentages (10-15%) produce a slower ferment with more complex flavor. Adjust based on ambient temperature and desired fermentation time.
What salt percentage should I use in sourdough?
Most sourdough recipes use 1.8-2.2% salt (relative to flour weight). The standard is 2%. Too little salt and bread tastes flat and ferments too fast. Too much salt inhibits yeast activity and creates overly salty bread.
Can I add inclusions like seeds or nuts?
Yes. Inclusions (seeds, nuts, dried fruit, olives, cheese) are typically added at 15-30% of flour weight. They do not affect hydration calculations since they are added separately. Add them during the stretch-and-fold phase rather than at the start.
Why do I need to weigh ingredients instead of using volume measurements?
Volume measurements are imprecise for baking. A cup of flour can weigh anywhere from 120g to 160g depending on how it is scooped. Weight measurements are precise and reproducible every time. Use a digital kitchen scale — it is the most important tool for consistent sourdough baking.