What Is the Sourdough Calculator?

The Sourdough Calculator helps you determine the exact amounts of flour, water, starter (levain), and salt for your sourdough bread recipe. It uses baker's percentages — the standard method professional bakers use where every ingredient is expressed as a percentage of the total flour weight.

Why Use Baker's Percentages?

Baker's percentages make it easy to scale recipes up or down while maintaining the same ratios. Whether you're baking one loaf or ten, simply change the flour weight and all other ingredients adjust automatically.

Understanding True Hydration

Your sourdough starter contains both flour and water (typically at 100% hydration, meaning equal parts flour and water). The True Hydration calculation accounts for this hidden flour and water, giving you a more accurate picture of your dough's actual hydration level.

How to Use the Sourdough Calculator

Choose a Recipe Preset

Select from four common sourdough styles to get started quickly:

Basic Sourdough (70% hydration) — Great for beginners
High Hydration (80% hydration) — Open crumb, more challenging
Whole Wheat (75% hydration, 25% starter) — Nutty flavor, denser crumb
Rye (65% hydration) — Earthy, robust flavor

Set Your Flour Amount

Enter the total flour weight in grams, or switch to By Number of Loaves mode and specify how many loaves you want along with the desired weight per loaf. The calculator will determine the flour needed automatically.

Adjust Percentages

Fine-tune the hydration, starter, and salt percentages using the input fields or sliders. The recipe results update instantly as you make changes.

Build Your Levain

Use the Levain Builder section to calculate exactly how much seed starter, flour, and water you need. Adjust the feed ratio (default 1:5:5) based on your starter's strength and your schedule.

Follow the Timeline

Select your room temperature (Warm or Cool) and follow the 8-step baking timeline from feeding your levain through to the final bake.

Features

Baker's Percentage Calculator

Enter your flour weight and adjust hydration, starter, and salt percentages. The calculator instantly computes the exact gram amounts for each ingredient, along with the total dough weight.

Flexible Input Modes

Calculate by flour weight when you know how much flour you have, or by number of loaves when you want a specific yield. The calculator handles the math for you.

Recipe Presets

Start with one of four proven sourdough recipes — Basic, High Hydration, Whole Wheat, or Rye — then customize to your taste.

True Hydration Display

See both the apparent hydration (what you set) and the true hydration (accounting for flour and water within the starter). This helps you understand how your dough will actually behave.

Levain Builder

Calculate the exact amounts of seed starter, flour, and water needed to build your levain. Customize the feed ratio and the calculator includes a 10% buffer so you always have enough.

Baking Timeline

A complete 8-step schedule from feeding your levain to pulling bread from the oven. Toggle between warm (24-27°C) and cool (18-21°C) environments to get accurate timing for your kitchen.

Frequently Asked Questions

What is baker's percentage?

Baker's percentage expresses each ingredient as a percentage of the total flour weight. For example, 70% hydration means you use 70g of water for every 100g of flour. This system makes it easy to scale recipes to any size.

What hydration should I use for sourdough?

Beginners should start with 65-70% hydration for a more manageable dough. As you gain experience, try higher hydrations (75-85%) for a more open crumb structure. The ideal hydration also depends on your flour type — whole wheat and rye typically need more water.

Best practice: Start at 70% hydration to develop your technique, then gradually increase as you become comfortable handling wetter doughs.

What is the difference between apparent and true hydration?

Apparent hydration is the water percentage you set in the recipe. True hydration accounts for the flour and water already present in your starter (assumed to be 100% hydration, meaning 50/50 flour and water). True hydration is always slightly higher than apparent hydration.

Apparent

What You Set

Water added to recipe
Doesn't include starter water
Example: 70%

True

Actual Hydration

Total water in dough
Includes starter water
Example: 75%

What feed ratio should I use for my levain?

A 1:5:5 ratio (1 part starter, 5 parts flour, 5 parts water) works well for most situations. Use a lower ratio like 1:3:3 for faster fermentation, or a higher ratio like 1:10:10 when you need to slow things down (overnight builds).

Feed Ratio	Fermentation Speed	Best For
1:3:3	Fast	Quick builds, same-day baking
1:5:5	Standard	Most recipes, balanced timing
1:10:10	Slow	Overnight builds, cold kitchens

How much salt should I use?

The standard range is 1.8-2.2% of flour weight. Most bakers use 2%. Less salt results in a milder flavor and faster fermentation; more salt slows fermentation and enhances flavor.

Recommended Salt Level 2.0%

Why does the timeline change with temperature?

Fermentation speed is directly affected by temperature. Warmer environments (24-27°C) speed up yeast and bacterial activity, while cooler temperatures (18-21°C) slow it down. Adjust the temperature setting to match your kitchen for more accurate timing.

Pro tip: Use a kitchen thermometer to measure your actual room temperature for the most accurate timeline predictions.