Sourdough Hydration Calculator
Enter flour, water, starter weight, and starter hydration to calculate total sourdough hydration. Or enter a target hydration to solve for the additional water required after accounting for the flour and water already inside the starter or levain.
Additional
100% means equal flour and water by weight. Lower is stiffer; higher is more liquid.
Changes visible rounding only; the calculation keeps its full numeric precision.
Starter hydration has no effect when the starter amount is zero.
How to use the Sourdough Hydration Calculator
Choose Calculate hydration when you already know how much flour and water are going into the dough. Enter the flour added directly, water added directly, and any starter or levain.
Choose Water for target when you know the flour, starter, and hydration percentage you want. The calculator determines how much additional water is required after accounting for water already present in the starter.
Starter hydration defaults to 100%. Open Additional when your starter is stiffer or more liquid, or when you want to change the displayed decimal precision.
The result always includes the flour and water inside the starter rather than treating starter weight as a separate ingredient that has no effect on hydration.
What dough hydration means
Dough hydration expresses water as a percentage of total flour weight.
A dough with 350 grams of total water and 500 grams of total flour is at 70% hydration.
In baker's percentage, flour is the 100% reference. A 75% hydration dough therefore contains 75 grams of water for every 100 grams of flour.
Hydration is a formula ratio, not a rating of whether a bread recipe is good or bad.
| Hydration | Total flour | Total water |
|---|---|---|
| 60% | 500 g | 300 g |
| 65% | 500 g | 325 g |
| 70% | 500 g | 350 g |
| 75% | 500 g | 375 g |
| 80% | 500 g | 400 g |
Why sourdough starter must be included
A starter or levain contributes both flour and water to the final dough.
For example, 100 grams of starter at 100% hydration contains 50 grams of flour and 50 grams of water.
If a recipe contains 500 grams of added flour, 350 grams of added water, and that 100-gram starter, the complete dough contains 550 grams of flour and 400 grams of water.
The resulting hydration is therefore about 72.73%, not 70%.
What 100% starter hydration means
Starter hydration is calculated as starter water divided by starter flour, multiplied by 100.
A 100% hydration starter contains equal weights of flour and water.
This does not mean that water makes up 100% of the starter's total weight. A 100-gram starter at 100% hydration contains approximately 50 grams flour and 50 grams water.
Starter hydration is a baker's-percentage relationship using flour as the reference.
| Starter hydration | Starter flour | Starter water | Total starter |
|---|---|---|---|
| 50% | 100 g | 50 g | 150 g |
| 60% | 100 g | 60 g | 160 g |
| 100% | 50 g | 50 g | 100 g |
| 125% | 100 g | 125 g | 225 g |
Stiff and liquid starters
A starter below 100% hydration contains less water than flour by weight and is commonly described as stiff.
For example, 160 grams of starter at 60% hydration contains 100 grams of flour and 60 grams of water.
A starter above 100% hydration contains more water than flour. A 225-gram starter at 125% hydration contains 100 grams flour and 125 grams water.
Because the flour-to-water split changes, two equal weights of starter can affect final dough hydration differently when their starter hydrations differ.
How Water for target mode works
Target mode starts by separating the entered starter into flour and water.
Starter flour is added to the flour entered directly to obtain total flour.
The target hydration percentage is then multiplied by that total flour to determine how much total water the final dough should contain.
Finally, the water already present in the starter is subtracted. The remainder is the amount of additional water to add.
| Added flour | Starter | Total flour | Target hydration | Water to add |
|---|---|---|---|---|
| 500 g | 100 g at 100% | 550 g | 70% | 335 g |
| 500 g | 100 g at 100% | 550 g | 75% | 362.5 g |
| 500 g | 100 g at 100% | 550 g | 80% | 390 g |
Example: water needed for 75% hydration
Suppose the dough contains 500 grams of added flour and 100 grams of starter at 100% hydration.
The starter contributes 50 grams flour and 50 grams water, so total flour is 550 grams.
At 75% hydration, 550 grams of flour requires 412.5 grams of total water.
Because the starter already contributes 50 grams of water, the final mix needs another 362.5 grams of water.
Why target water is not simply flour × hydration
Multiplying only the added flour by a target percentage ignores the starter.
With 500 grams of added flour and a 100-gram 100%-hydration starter, simply calculating 500 × 75% would suggest 375 grams of water.
But the starter adds another 50 grams flour and 50 grams water. The actual target is based on 550 grams total flour, and the starter water must then be deducted.
That is why the correct additional-water result for this example is 362.5 grams rather than 375 grams.
When a target hydration is already too low
Starter water is already physically present in the formula before any additional water is added.
If that starter water alone produces a hydration greater than the requested target, the target cannot be reached by adding a non-negative amount of water.
The calculator reports this instead of returning a negative water amount.
To lower the hydration, reduce the starter, use a stiffer starter, increase the flour, or choose a higher target.
The baker's-percentage visual
The result compares total flour and total water on a baker's-percentage scale.
Total flour is always the 100% reference. A 70% hydration result therefore shows water at 70% relative to flour.
If hydration exceeds 100%, the scale expands so the water amount can extend beyond the flour reference without being clipped.
The visual represents ingredient proportions, not dough consistency, fermentation progress, or expected crumb structure.
Hydration does not predict how the dough will feel
Two formulas with the same numerical hydration can behave very differently.
Whole-grain flour, rye, flour strength, protein content, milling, damaged starch, bran, temperature, autolyse, mixing, fermentation, salt, and other ingredients can all alter water absorption and dough handling.
A 75% dough made with one flour may feel substantially firmer or looser than a 75% dough made with another flour.
Use hydration as a reproducible formula measurement rather than a guarantee of a particular dough texture.
Higher hydration does not guarantee an open crumb
Adding more water can change dough extensibility and handling, but hydration alone does not determine crumb structure.
Fermentation quality, gluten development, flour strength, degassing, shaping, proofing, gas retention, scoring, and baking also affect the finished loaf.
A poorly fermented high-hydration dough can produce a dense loaf, while a well-managed lower-hydration formula can produce an open structure.
Hydration should therefore be interpreted together with the complete bread process.
What counts as flour in this calculator
Total flour equals flour entered directly plus flour contained in the starter.
If several flour types are used in the final dough, add their weights together before entering the Flour added amount.
The same applies when the starter itself contains a blend of flours: only its total flour contribution matters for this hydration calculation.
The calculator does not distinguish bread flour, all-purpose flour, whole wheat, rye, or other flour types because hydration arithmetic uses their weight even though their absorption characteristics can differ.
What counts as water in this calculator
The calculator counts the plain water entered directly plus the water contained in the starter.
It does not automatically estimate the water content of milk, eggs, butter, fruit, vegetables, syrups, soaked grains, or other ingredients.
Broader professional bread formulas can account for additional liquids in different ways depending on the formula and the purpose of the calculation.
When those ingredients materially affect the formula, treat this tool as a flour-water hydration calculator rather than a complete dough-composition model.
Display precision and ingredient accuracy
The Additional control changes only how many decimal places are shown.
The internal calculation is performed before display rounding.
Showing extra decimal places does not make an ingredient measurement more accurate than the scale used to weigh it.
For practical baking, choose a precision that matches the batch size and the resolution of your scale.
What this calculator does not calculate
The tool does not calculate salt percentage, inoculation percentage, prefermented-flour percentage, total dough yield, dough temperature, fermentation time, proofing time, ingredient cost, or loaf size.
It does not formulate a complete bread recipe or recommend a hydration for a particular flour or bread style.
It also does not automatically convert volume measurements such as cups into ingredient weights.
Use the related recipe-scaling, pizza-dough, yeast-conversion, or grams-to-cups tools when those calculations are needed.
Sourdough hydration formulas
The starter is first separated into flour and water. Forward mode calculates hydration from total flour and water; target mode solves for the additional water required.
- Total starter or levain weight
- Starter hydration percentage
- Flour contained in the starter
- Water contained in the starter
- Flour added directly to the dough
- Water added directly to the dough
- Total flour including starter flour
- Total water including starter water
- Calculated final dough hydration
- Desired target hydration
- Total water required at the target hydration
- Hydration already contributed by starter when no additional water is added
Examples
Calculate hydration with a 100% starter
500 g added flour, 350 g added water, and 100 g starter at 100% hydration.
Starter contributes 50 g flour and 50 g water. Total flour is 550 g, total water is 400 g, and final hydration is approximately 72.73%.
Find water for 75% hydration
500 g added flour, 100 g starter at 100% hydration, target hydration 75%.
Total flour is 550 g. The target requires 412.5 g total water. Starter already contributes 50 g, so add 362.5 g water.
Dough without starter
500 g flour, 350 g water, no starter.
Total flour is 500 g, total water is 350 g, and hydration is 70%.
Stiff starter
160 g starter at 60% hydration.
The starter contains 100 g flour and 60 g water.
Liquid starter
225 g starter at 125% hydration.
The starter contains 100 g flour and 125 g water.
Target already below starter contribution
100 g added flour, 200 g starter at 100% hydration, target hydration 40%.
The starter contributes 100 g flour and 100 g water. Total flour is 200 g, so starter water alone already produces 50% hydration. A 40% target cannot be reached by adding water.
Reduce the starter, use a stiffer starter, increase the flour, or choose a target of at least 50%.
Target hydration above 100%
500 g added flour, no starter, target hydration 110%.
Total flour is 500 g, so the target requires 550 g of water.
Hydration above 100% is mathematically valid because baker's percentage compares water weight with flour weight.
Frequently Asked Questions
How do I calculate sourdough hydration?
Divide total water by total flour and multiply by 100. Include the flour and water inside any starter or levain.
Does sourdough starter count toward hydration?
Yes. Both the flour and water contained in the starter are part of the final dough and should be included in total hydration.
What does 100% hydration starter mean?
It means the starter contains equal weights of water and flour. For example, 100 grams of starter at 100% hydration contains about 50 grams flour and 50 grams water.
Does 100% starter hydration mean the starter is all water?
No. Starter hydration expresses water relative to flour. Equal flour and water weights produce 100% hydration.
How much flour and water are in 100 grams of 100% hydration starter?
Approximately 50 grams flour and 50 grams water.
How do I calculate water for a target sourdough hydration?
Calculate total flour including starter flour, multiply it by the target hydration percentage, then subtract the water already contained in the starter.
How much water do I need for 75% hydration?
It depends on total flour, including flour inside the starter. For 500 grams added flour plus 100 grams of 100%-hydration starter, total flour is 550 grams and the additional water required is 362.5 grams.
Why does the target-water result seem lower than flour multiplied by the hydration percentage?
Because the starter may already contain water. Target mode calculates the required total water and then subtracts the starter water already present.
Why does the calculator say my target hydration is too low?
The starter can already contribute more water than that target allows. Since the calculator solves for additional water and cannot add a negative amount, you need to change the flour, starter quantity, starter hydration, or target.
Can sourdough hydration be over 100%?
Yes. Hydration compares water weight with flour weight, so a formula containing more water than flour by weight can exceed 100%.
Can I use a stiff starter?
Yes. Enter its actual hydration percentage. A stiff starter contains less water relative to flour than a 100% starter.
Can starter hydration exceed 100%?
Yes. A starter above 100% hydration contains more water than flour by weight.
Can I calculate hydration with no starter?
Yes. Enter zero or leave the starter amount blank. The calculation then uses only the directly added flour and water.
Does starter hydration matter when starter is zero?
No. When no starter is included, the starter-hydration setting does not affect the result.
What is a good sourdough hydration?
There is no universal best percentage. Flour type, bread style, fermentation, mixing, shaping, and the baker's preferred handling characteristics all matter.
Does higher hydration guarantee a more open crumb?
No. Hydration is only one factor. Fermentation, flour strength, gluten development, shaping, gas retention, proofing, and baking also influence crumb structure.
Does the calculator include water from milk or eggs?
No. It counts plain added water and the water inside the starter. Other water-containing ingredients are not automatically converted.
Does the calculator include all flour types?
Yes mathematically, as long as you add their weights together. The tool does not distinguish their different absorption or dough-behavior characteristics.
Does hydration predict fermentation time?
No. Fermentation also depends on inoculation, starter activity, dough temperature, flour, salt, room conditions, and other factors.
Does changing display precision change the hydration calculation?
No. It changes only visible rounding. The underlying calculation uses the unrounded numerical values.