What is sourdough starter hydration?

Hydration is the weight of water divided by the weight of flour, expressed as a percentage. A 100% hydration starter contains equal weights of flour and water, giving a thick batter-like consistency. A 75% hydration starter is stiffer; a 125% starter is thinner and more pourable.

What does the feeding ratio mean?

The feeding ratio is written as starter : flour : water. A 1:1:1 ratio means you feed equal weights of each. A 1:2:2 ratio means you add twice as much flour and twice as much water as the starter weight. Higher ratios dilute the starter more, which slows fermentation and is useful for timing longer builds.

How much starter should I keep?

Most home bakers maintain 20–50g of starter between bakes. A small amount reduces waste during routine feedings. When you need more for a recipe, simply scale up one feeding using the Build mode in this calculator.

What hydration works best for sourdough bread?

Most home bakers use a 100% hydration starter because it is easy to gauge activity by the rise-and-fall pattern and the bubble structure. Bakers making stiffer doughs (e.g. bagels, rye) sometimes maintain a 50–75% hydration starter for its milder flavor and longer refrigerator life.

How long does it take for the starter to peak after feeding?

At room temperature (70–76°F / 21–24°C) a 1:1:1 feeding typically peaks in 4–8 hours. A 1:5:5 feeding may take 8–14 hours. Cooler temperatures slow fermentation; warmer temperatures speed it up. Use the starter when it has doubled and shows domed or just-starting-to-fall signs.

Can I use whole-wheat or rye flour?

Yes. Whole-wheat and rye flours ferment faster because they contain more wild yeast and bacteria. They also absorb more water. If you blend whole-grain flour into your starter, you may need to reduce water slightly to maintain the same dough consistency, or simply note that peak timing will be shorter.

Sourdough Starter Calculator

Name: Sourdough Starter Calculator
Availability: InStock
Author: Nham Vu

Enter your starter amount, desired hydration, and feeding ratio to get exact flour and water amounts for feeding your sourdough starter.

Hydration Presets

Feeding Parameters

Starter Weight (g)

Weight of starter before feeding.

Target Hydration (%)

Feeding Ratio (starter : flour : water)

Starter

Flour

Water

Enter your starter weight above to see the feeding plan.

Levain Build Parameters

Target Levain Weight (g)

Total grams of levain your recipe requires.

Target Hydration (%)

Seed Percentage (%)

Starter as % of total levain. Typical: 10–25%.

Quick seed %:

Enter your target levain weight to see the build breakdown.

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Summary

Enter your starter amount, desired hydration, and feeding ratio to get exact flour and water amounts for feeding your sourdough starter.

How it works

Enter the weight of your existing starter in grams.
Choose your target hydration percentage (100% is equal parts flour and water by weight).
Set your feeding ratio — the multiplier applied to each component (starter : flour : water).
The calculator instantly shows flour grams, water grams, and total starter weight after feeding.
Use the Build mode to plan a levain from a target final weight and hydration.
Copy the feeding plan to your clipboard for reference while baking.

Use cases

Calculate exact flour and water amounts to feed a sourdough starter at 100% hydration.
Plan a stiff starter feed at 50–75% hydration for certain bread styles.
Build a levain to a specific total weight required by a recipe.
Scale feedings up or down when maintaining a larger or smaller starter jar.
Check how much total starter you will have after a 1:2:2 or 1:5:5 feeding.
Experiment with different hydration levels to find the right consistency for your starter.
Understand the relationship between feeding ratio and starter activity timing.
Plan overnight builds so your starter peaks when you are ready to bake.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu