Sourdough Hydration Calculator

Last updated: Jun 9, 2026

Calculate exact ingredient weights for sourdough bread using baker's math. Build a recipe from target percentages or analyze an existing one.

Bread Presets

Total Flour Weight ?Total flour weight for one loaf. This is the base that all baker's percentages reference.

Target Hydration ?Ratio of total water to total flour. 65-70% for beginners, 70-80% for experienced bakers.

Starter Amount ?Starter as % of total flour. 15-25% is typical. Higher means faster fermentation and stronger flavor.

Starter Hydration ?Your starter's hydration level. 100% (equal flour and water) is the most common.

Salt ?Salt as % of total flour. 1.8-2.2% is the typical range. Below 1.5% tastes bland; above 2.5% is too salty for most.

Loaves ?Number of loaves to bake. All ingredient weights are multiplied accordingly.

Starter Hydration

Flour Added ?Flour you add directly to the dough (not counting what is in the starter).

Water Added ?Water you add directly to the dough (not counting what is in the starter).

Starter Weight ?Total weight of sourdough starter used in the recipe.

Starter Hydration ?Your starter's hydration level. 100% (equal flour and water) is the most common.

Salt Weight ?Weight of salt added to the dough.

Starter Hydration

Your Recipe

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Overall Hydration

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Total Dough

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Pre-Fermented Flour

Ingredient	Weight	Baker's %

Starter Breakdown

Flour in starter —

Water in starter —

About This Tool

This sourdough hydration calculator uses baker's math — the professional formula system where every ingredient is expressed as a percentage of the total flour weight. It automatically decomposes your sourdough starter into its flour and water components, giving you the true overall hydration of your dough. The calculator supports two modes: Recipe Builder lets you set target percentages and get exact ingredient weights, while Recipe Analyzer takes your existing recipe weights and reveals the baker's percentages and actual hydration. Both modes show the pre-fermented flour percentage (PFF) to help you understand flavor development.

Sources: The Perfect Loaf · Sourdough.co.uk · The Pantry Mama

How to Use

Choose Recipe Builder to create a recipe from target percentages, or Recipe Analyzer to evaluate an existing recipe's weights.
Enter your flour weight and adjust percentages (or enter weights in Analyzer mode). Use bread presets for quick starting points.
Click Calculate to see your recipe with exact weights, baker's percentages, starter breakdown, and hydration analysis.

How to Use

Choose Recipe Builder to create a recipe from target percentages, or Recipe Analyzer to evaluate an existing recipe's weights.
Enter your flour weight and adjust percentages (or enter weights in Analyzer mode). Use bread presets for quick starting points.
Click Calculate to see your recipe with exact weights, baker's percentages, starter breakdown, and hydration analysis.

Methodology

All calculations use standard baker's math formulas verified against professional references. Hydration is calculated as total water divided by total flour, multiplied by 100. Starter decomposition uses the formula: flour in starter = starter weight / (1 + starter hydration / 100). The pre-fermented flour percentage (PFF) equals the flour in the starter divided by total flour, multiplied by 100. In Recipe Builder mode, total flour is your input. The calculator computes starter weight, decomposes it into flour and water, then calculates the remaining flour and water you need to add. In Analyzer mode, the process reverses — it takes your measured weights and computes the percentages.

Sources: King Arthur Baking · SFBI · Busby's Bakery · Breadtopia

Understanding Your Results

The results table shows exactly what you need to measure out. In Recipe Builder mode, "Flour" and "Water" are the amounts you add directly to the bowl — the starter's contribution is already accounted for. The Baker's % column shows each ingredient as a percentage of total flour weight (flour is always 100%). Overall Hydration tells you the dough's texture character: below 65% is stiff and easy to shape, 65-75% is the sweet spot for most sourdough, and above 80% produces very wet, open-crumb bread that requires advanced handling. The Pre-Fermented Flour (PFF) percentage indicates flavor intensity: 10-15% is mild, 20-30% is noticeably tangy.

Sources

Practical Examples

Example 1 — Basic sourdough loaf: Set flour to 500g, hydration to 70%, starter to 20% at 100% hydration, salt to 2%. The calculator shows you need 450g flour, 300g water, 100g starter, and 10g salt. Total dough weight is 860g. The starter contributes 50g flour and 50g water. Pre-fermented flour is 10%. Example 2 — Analyzing a recipe: Enter 450g flour, 325g water, 150g starter at 100% hydration, 12g salt. The calculator reveals 72.4% overall hydration, 16.2% starter percentage, 1.9% salt percentage, and 8.1% PFF. The 150g starter added 75g flour (total flour: 525g) and 75g water (total water: 400g).

Sourdough Baking Tips

Start with 68-70% hydration if you are new to sourdough. This produces a manageable dough with good results. Increase by 2-3% at a time as you gain experience. Weigh everything in grams on a digital scale. Volume measurements (cups, tablespoons) are too imprecise for bread baking where small differences matter. Even a 5g variance in water can noticeably change the dough feel. Use your starter when it has doubled and is bubbly — usually 4-8 hours after feeding, depending on room temperature. An under-ripe starter will give weak rise, and an over-ripe starter produces excess acidity. Whole grain flours absorb more water. If switching from white flour to whole wheat, add 5-15% more hydration. Start low and increase gradually until the dough feels similar to your white flour version. Salt strengthens gluten and controls fermentation speed. If you are reducing salt for health reasons, do not go below 1.5% — it will affect both flavor and dough structure significantly.

Sources: The Perfect Loaf · Sourdough.co.uk · The Pantry Mama

All calculations are performed locally in your browser. No data is sent to any server.

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Frequently Asked Questions

What is sourdough hydration?

Hydration is the ratio of total water to total flour in your dough, expressed as a percentage. For example, 350g of water with 500g of flour gives 70% hydration. This includes the water and flour contributed by your sourdough starter. Higher hydration creates a more open crumb and chewier texture, while lower hydration produces a tighter, denser crumb. Most sourdough recipes fall between 65% and 80% hydration.

Why does starter hydration matter?

Your sourdough starter contains both flour and water. A 100% hydration starter (the most common) is equal parts flour and water by weight, so 100g of starter adds 50g of flour and 50g of water to your dough. A stiff starter at 50% hydration would contribute about 67g of flour and only 33g of water per 100g. If you don't account for this, your actual dough hydration will be different from what you intended. This calculator automatically breaks down the starter's contribution for accurate results.

What is pre-fermented flour percentage (PFF)?

Pre-fermented flour percentage (PFF) tells you what fraction of your total flour has already been fermented in the starter. It is calculated as the flour in your starter divided by the total flour in the recipe, multiplied by 100. A PFF of 10-15% gives a milder sourdough flavor with slower fermentation, while 25-30% produces a stronger tangy flavor with faster fermentation. Most home sourdough recipes fall between 10% and 20% PFF.

How do I adjust hydration for different flour types?

Different flours absorb water at different rates. Bread flour is the baseline. Whole wheat flour absorbs significantly more water due to bran and germ — add 5-15% more hydration than you would with white flour. Rye flour also absorbs more water (add 5-10%), and its high pentosan content makes the dough feel different. Spelt flour needs slightly more water (add 3-5%) but has weaker gluten, so handle it gently. All-purpose flour absorbs slightly less than bread flour (reduce by 3-5%). These are starting points — adjust based on your specific flour and conditions.

What hydration should a beginner use for sourdough?

If you are new to sourdough baking, start with 68-70% hydration using bread flour. This produces a dough that is manageable to shape while still giving a good open crumb. Use a standard 100% hydration starter at 20% of total flour, and 2% salt. As you gain confidence, gradually increase hydration by 2-3% at a time. Many experienced bakers work in the 72-78% range for artisan loaves. High hydration doughs (above 80%) require advanced shaping techniques and can be frustrating for beginners.

How does this calculator handle the starter's flour and water?

The calculator uses a standard decomposition formula verified by King Arthur Baking and other professional sources. For a starter at H% hydration, the flour component equals the starter weight divided by (1 + H/100), and the water is the remainder. For example, 100g of starter at 100% hydration contains 50g flour and 50g water. These amounts are subtracted from the recipe totals so you know exactly how much flour and water to add separately. The results panel clearly shows both the recipe amounts (what you measure out) and the overall totals (including starter contribution).

Can I scale the recipe for multiple loaves?

Yes. In Recipe Builder mode, set the number of loaves and the calculator will multiply all ingredient weights proportionally while keeping the baker's percentages and hydration the same. The results show both per-loaf and total amounts. This uses the Formula Conversion Factor method recommended by King Arthur Baking for scaling professional bakery formulas.

Is my recipe data stored or sent anywhere?

No. All calculations run entirely in your browser. No recipe data, ingredient amounts, or personal information is sent to any server. Your recipes remain completely private on your device.