Cooking

Sourdough Hydration Calculator (Baker's Percentage)

Q: What is hydration in sourdough?

Hydration is the **ratio of total water to total flour**, expressed as a percentage where flour is 100%. A **75% hydration** dough has 75 g of water per 100 g of flour, counting both the water you add and the water inside your starter.

Q: Why does the starter count toward hydration?

Your starter is made of **flour and water**, so both contribute to the dough's totals. Ignoring the starter makes your dough **wetter** than intended. This calculator splits the starter and subtracts its water from the water you add.

Q: How much water is in a 100% hydration starter?

Exactly **half** its weight. A **100 g** starter at 100% hydration is **50 g flour + 50 g water**. A 50% (stiff) starter of 100 g is about 67 g flour and 33 g water.

Q: What hydration should a beginner use?

Around **68–72%**. That gives a dough that holds its shape and is easy to handle while you learn. Higher hydrations (80%+) create a more open crumb but are sticky and harder to shape.

Q: How much salt should I use?

Typically **2% of the total flour** (a range of 1.8–2.2% is common). For 550 g of total flour, that is about **11 g** of salt. Salt controls fermentation and strengthens the dough.

Q: How much starter should I add?

Commonly **15–25% of the total flour** by weight. More starter ferments the dough faster; less starter means a longer, slower rise with more flavor development.

Q: Does whole wheat or rye change the water?

Yes. Whole-grain flours **absorb more water** than white bread flour, so a dough may feel stiffer at the same calculated hydration. Add a little extra water and adjust by feel when using whole wheat or rye.

Q: How do I scale my recipe up or down?

Because everything is a **baker's percentage of flour**, just change your flour weight and keep the same percentages. Double the flour and the water, salt, and starter all scale proportionally — this tool recalculates instantly.

Calculate sourdough hydration the right way — counting the flour and water in your starter. Enter your flour, starter, and target hydration to get exactly how much water to add, plus salt and total dough weight.

Data verified · July 2026
Edited by Martín Rodríguez
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Edited by: Martín Rodríguez (editorial policy )

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Hydration is the single most important number in sourdough — it is the ratio of total water to total flour, written as a baker's percentage where flour is always 100%. A '75% hydration' dough has 75 g of water for every 100 g of flour.

The twist with sourdough (versus a yeasted dough) is the starter. Your levain is itself made of flour and water, and both count toward the dough's hydration. A generic baker's-percentage tool that ignores the starter will overshoot your water. This calculator splits the starter into its flour and water and tells you exactly how much additional water to add.

Enter the flour you add, your starter weight and its hydration (100% for a standard 1:1 starter), your target hydration, and your salt percentage. If you also want a simple yeast-dough version, use the baker's percentage calculator.

When to use this calculator

Find exactly how much water to add for a target hydration.
Account for the flour and water inside your starter.
Scale a sourdough recipe up or down by baker's percentage.
Hit a specific hydration for a more open crumb.
Calculate salt at the correct percentage of total flour.
Convert a stiff starter (e.g. 50%) into the right water.
Plan total dough weight to fit your banneton or loaf tin.
Dial in a beginner-friendly 68–72% dough.

Water to add for 500 g flour + 100 g of 100% starter, by target hydration

Target hydration	Total flour	Total water	Water to add
65%	550 g	358 g	308 g
70%	550 g	385 g	335 g
75%	550 g	413 g	363 g
80%	550 g	440 g	390 g
85%	550 g	468 g	418 g

Assumes 100 g of 100%-hydration starter (50 g flour + 50 g water). Water to add = total flour × hydration − 50 g starter water. Whole-grain flours absorb more; adjust by feel.

How it works

The math, with the starter included

Starter flour = starter weight ÷ (1 + starter hydration/100)
Starter water = starter weight − starter flour
Total flour   = added flour + starter flour
Target water  = total flour × target hydration/100
Water to add  = target water − starter water
Salt          = total flour × salt %

A 100% hydration starter is equal parts flour and water, so 100 g of it is 50 g flour + 50 g water. A stiff 50% hydration starter of 100 g is ~67 g flour + ~33 g water — the tool handles any ratio you enter.

Why counting the starter matters

Say you want 75% hydration with 500 g flour and 100 g of 100% starter. If you ignore the starter and just add 75% of 500 = 375 g water, your real hydration is higher, because the starter already brought 50 g water and 50 g flour. The correct water to add is 363 g, not 375 g — small, but it compounds with bigger levains.

Hydration ranges

Hydration	Feel & result
< 65%	Stiff, easy to shape, tighter crumb (bagels, sandwich loaves)
65–74%	Reliable all-purpose sourdough
75–84%	Open, airy crumb; needs good handling
≥ 85%	Very slack and sticky; ciabatta-style, advanced

New to sourdough? Start around 68–72% so the dough is manageable while you learn to shape.

Salt and starter percentages

Salt is typically 1.8–2.2% of total flour — 2% is the common default.

Starter is often 15–25% of total flour; more starter ferments faster.

Disclaimer

A baking-math tool, not a recipe. Flours absorb water differently (whole wheat and rye drink more), so treat the water-to-add as a starting point and adjust by feel. Room temperature and fermentation time also affect the final dough.

Example: 500 g flour, 100 g starter (100% hydration), 75% target, 2% salt

Starter splits into 50 g flour + 50 g water.

Total flour = 500 + 50 = 550 g.

Target water = 550 × 75% = 413 g.

Water to add = 413 − 50 (from starter) = 363 g; salt = 550 × 2% = 11 g.

Add 363 g water and 11 g salt (~974 g dough)

Frequently asked questions

What is hydration in sourdough?

Hydration is the ratio of total water to total flour, expressed as a percentage where flour is 100%. A 75% hydration dough has 75 g of water per 100 g of flour, counting both the water you add and the water inside your starter.

Why does the starter count toward hydration?

Your starter is made of flour and water, so both contribute to the dough's totals. Ignoring the starter makes your dough wetter than intended. This calculator splits the starter and subtracts its water from the water you add.

How much water is in a 100% hydration starter?

Exactly half its weight. A 100 g starter at 100% hydration is 50 g flour + 50 g water. A 50% (stiff) starter of 100 g is about 67 g flour and 33 g water.

What hydration should a beginner use?

Around 68–72%. That gives a dough that holds its shape and is easy to handle while you learn. Higher hydrations (80%+) create a more open crumb but are sticky and harder to shape.

How much salt should I use?

Typically 2% of the total flour (a range of 1.8–2.2% is common). For 550 g of total flour, that is about 11 g of salt. Salt controls fermentation and strengthens the dough.

How much starter should I add?

Commonly 15–25% of the total flour by weight. More starter ferments the dough faster; less starter means a longer, slower rise with more flavor development.

Does whole wheat or rye change the water?

Yes. Whole-grain flours absorb more water than white bread flour, so a dough may feel stiffer at the same calculated hydration. Add a little extra water and adjust by feel when using whole wheat or rye.

How do I scale my recipe up or down?

Because everything is a baker's percentage of flour, just change your flour weight and keep the same percentages. Double the flour and the water, salt, and starter all scale proportionally — this tool recalculates instantly.

Sources & references

Methodology & trust

Editorial

Cooking calculator with its formula verified automatically against King Arthur Baking — Bread hydration, explained, per our editorial policy and methodology.

Updates

Updated: July 2026. Parameters are verified periodically against the cited sources.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). Sourdough Hydration Calculator (Baker's Percentage). Hacé Cuentas. https://hacecuentas.com/en/sourdough-hydration-bakers-percentage-calculator

Content licensed under CC-BY 4.0 — reuse it citing the source with a link to Hacé Cuentas.

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