A sourdough bread calculator uses baker's percentages to determine the exact amount of flour, water, starter, and salt you need for your loaf. Baker's percentages express every ingredient as a proportion of the total flour weight, making it easy to scale recipes up or down while keeping the hydration and flavour balanced perfectly.
Recipe Parameters
Your Sourdough Recipe
Suggested Timeline
How to Use the Sourdough Bread Calculator
Baking great sourdough starts with getting the ingredient ratios right. Professional bakers use baker's percentages — a system where every ingredient is expressed as a percentage of the total flour weight — to ensure consistency regardless of batch size. Our free sourdough bread calculator does the maths for you, so you can focus on technique rather than arithmetic.
Step 1: Set your flour weight
Enter the total flour weight in grams. This is the foundation of baker's percentages — flour is always 100%. A good starting point for a single loaf is 500g. For a larger loaf, try 750g. The calculator supports values from 100g to 5000g, so it works for a single roll or a full bakery batch.
Step 2: Adjust hydration and percentages
Use the sliders to set your desired hydration (60-100%), starter amount (10-40%), and salt (1-3%). Hydration is the most important variable — it controls how open and airy your crumb will be. Beginners should stay around 70-72% for a dough that is easy to handle. More experienced bakers can push to 78-85% for a lighter, more hole-filled crumb.
Step 3: Account for starter hydration
Your sourdough starter contains both flour and water. A 100% hydration starter (the most common type) is equal parts flour and water by weight. If you maintain a stiffer starter (e.g., 60%), adjust the starter hydration slider accordingly. The calculator automatically subtracts the flour and water contributed by your starter from the recipe totals, giving you the precise amounts of additional flour and water to add.
Step 4: Choose number of loaves
Select how many loaves you want to bake (1-4). The calculator multiplies all ingredient amounts by the number of loaves and shows you the per-loaf dough weight so you can divide evenly. This is especially useful when baking multiple loaves in one session.
Step 5: Review and bake
The recipe card updates instantly as you change any input. It shows adjusted flour, adjusted water, starter, and salt — plus the total dough weight, per-loaf weight, and true hydration percentage. Follow the suggested timeline for a classic overnight cold-proof sourdough. Click Copy to save your recipe to the clipboard for reference while baking.
All calculations run locally in your browser. Nothing is stored or sent anywhere, so your sourdough recipe is completely private. Bookmark this page to return whenever you need to recalculate for a different batch size or hydration level.
FAQ
Is this sourdough calculator really free?
Yes, the sourdough bread calculator is completely free with no limits and no account required. Use it as often as you like. All calculations happen in your browser — nothing is stored or sent anywhere.
Is my recipe data safe and private?
Absolutely. Every calculation runs entirely in your browser using JavaScript. No data is sent to any server, stored in any database, or shared with anyone. You can even use the tool offline once the page has loaded.
What are baker's percentages and how do they work?
Baker's percentages express each ingredient as a percentage of the total flour weight. Flour is always 100%. If you use 500g flour and 75% hydration, the water amount is 375g. This system makes it easy to scale recipes to any size while keeping ratios consistent.
What hydration percentage should I use for sourdough bread?
Most sourdough recipes use 70-80% hydration. Beginners should start around 70-72% for easier handling. As you gain confidence, try 75-80% for a more open crumb. Very high hydration (85%+) produces artisan-style loaves but requires advanced shaping skills.
Why does the calculator adjust flour and water for the starter?
Sourdough starter contains both flour and water. A 100% hydration starter is half flour and half water by weight. The calculator subtracts the flour and water contributed by the starter from your totals so the final dough has the correct hydration and flour amount.
What does starter hydration mean?
Starter hydration is the ratio of water to flour in your sourdough starter, expressed as a percentage. A 100% hydration starter has equal parts flour and water by weight (e.g., 50g flour + 50g water). Most home bakers maintain a 100% hydration starter because it is easiest to manage.
How long should I bulk ferment my sourdough?
Bulk fermentation typically takes 4-6 hours at room temperature (around 24-26 C / 75-78 F). The exact time depends on your starter activity, ambient temperature, and flour type. Look for a 50-75% rise in dough volume and a jiggly, airy texture as signs of readiness.