Sourdough Hydration Calculator
Reveal the flour and water inside sourdough starter, combine them with the final mix, and calculate true hydration by weight. The ledger also reports baker’s percentages, target-hydration adjustment, current dough weight, and a clean scale factor for a chosen batch size.
Hydration is arithmetic, not a texture guarantee. Flour type, extraction, protein, damaged starch, temperature, mixing, autolyse, fermentation, inclusions, and handling all change how the same percentage feels.
Enter the current formula in grams
Enter zero to skip batch scaling. Scaling preserves the current formula, not the target-hydration adjustment.
Reconciled formula
Flour and water ledger balance will appear here.
Scaled current formula
Starter-aware hydration math
King Arthur Baking defines dough hydration as liquid weight divided by flour weight. For sourdough, flour and water inside the starter or preferment count toward the totals. A 100-gram starter at 100 percent hydration contains 50 grams flour and 50 grams water because its water equals 100 percent of its flour weight.
starter water = starter weight − starter flour
true hydration = total water ÷ total flour × 100
The default formula has 500 grams final-mix flour, 350 grams final-mix water, and 100 grams of 100 percent hydration starter. Total flour is 550 grams and total water is 400 grams, so true hydration is 72.73 percent—not the 70 percent obtained by ignoring the starter. Ten grams salt equals 1.82 percent of total flour. Starter flour is 9.09 percent of total flour, the prefermented-flour percentage.
To reach 75 percent hydration without changing flour, total water would be 412.5 grams. The ledger therefore shows a positive 12.5-gram water adjustment. That is a mathematical difference, not an instruction to pour all of it into a developed dough. Bakers may hold back water, use bassinage, or change mixing based on flour behavior and process.
Keep percentage definitions separate
- Hydration: total counted water divided by total flour.
- Starter hydration: water in the starter divided by flour in the starter.
- Prefermented flour: starter flour divided by total formula flour.
- Starter ratio shown here: whole starter weight divided by total flour. This is not the same as prefermented flour.
- Salt percentage: salt divided by total flour, consistent with baker’s math.
- Scale factor: desired dough weight divided by current dough weight.
Decide what counts as water
Water is straightforward, but milk, eggs, butter, honey, fruit puree, and other ingredients contain different amounts of water plus solids. Counting their whole weight as water can overstate functional hydration; excluding all of it can understate available moisture. The “other water-equivalent liquid” field should contain only the portion you intentionally treat as water under your documented formula convention.
Keep the convention consistent when comparing batches. If exact formulation matters, use ingredient composition data and a more detailed solids-and-water balance rather than assuming every liquid is 100 percent water.
Scaling preserves the entered formula
Current dough weight is the sum of final flour, final water, whole starter, other counted liquid, salt, and other ingredients. Dividing desired dough weight by that sum creates one factor applied to every ingredient. The default 960-gram dough scaled to 1,440 grams uses a factor of 1.5: 750 grams final flour, 525 grams final water, 150 grams starter, and 15 grams salt.
The scaled strip intentionally preserves the current 72.73 percent hydration. It does not apply the separate 12.5-gram target adjustment before scaling, because that would silently change both the formula and the desired dough total. To build a target-hydration formula, revise the water input explicitly, recalculate, and then scale the reconciled version.
| Change | Hydration effect | Ledger action |
|---|---|---|
| Add final-mix water | Raises total water and dough weight. | Increase the final water input. |
| Change starter weight at same starter hydration | Adds both flour and water in the starter’s ratio. | Update starter weight; review prefermented flour. |
| Change starter hydration | Changes the flour/water split inside the same starter weight. | Update starter hydration from actual build weights. |
| Add dry flour during handling | Lowers actual hydration and changes formula yield. | Record it as flour rather than treating it as invisible dusting. |
| Lose dough to bowl or tools | Does not change formula percentage if loss is representative. | Use a separate process-loss allowance for final piece weight. |
Hydration does not predict dough behavior by itself
A 75 percent whole-grain dough may feel firmer than a lower-hydration white-flour dough because flours absorb water differently. Protein quality, bran, starch damage, milling, age, and regional flour specifications matter. Salt, acidity, enzymes, prefermentation, mixing energy, folds, rest time, and dough temperature change strength and extensibility.
Record sensory and process observations beside the number: flour brand and lot, dough temperature, autolyse, mixing method, fold schedule, bulk endpoint, proof, shaping behavior, bake profile, loaf volume, crumb, and keeping quality. Change one variable at a time. Hydration is most useful as a reproducible coordinate in a larger formula, not as a ranking where higher is automatically better.
Starter readiness also is not encoded in hydration. A 100 percent hydration starter can be underfermented, mature, or past peak depending on temperature, feeding ratio, flour, inoculation, and time. King Arthur’s current feeding-ratio discussion explains that 1:1:1 means seed starter, flour, and water in equal weights and commonly creates a 100 percent hydration starter, but the ratio also changes the time to peak.
Test hydration changes as controlled batches
When moving from 72.7 to 75 percent, keep flour brand, starter build, salt, mixing, temperature, fermentation, shaping, and bake profile as consistent as practical. Weigh the proposed extra water instead of estimating a splash. Note whether it is included initially or held back, because the timing of addition can change dough development even when final hydration is identical.
Evaluate more than openness of crumb. Record dough strength, extensibility, sticking, ability to hold shape, fermentation signs, scoring, oven spring, crust, crumb texture, slicing, flavor, and keeping quality. A higher number that makes production unreliable is not automatically an improvement. Save the tested formula as a new version rather than overwriting the prior batch record.
Raw flour and dough safety
Fermentation does not make raw dough safe to taste. CDC states that most flour is raw and can contain harmful germs, and raw eggs can also carry Salmonella. Bake or cook dough according to a validated recipe or product direction. Keep raw flour and dough away from ready-to-eat foods, wash hands, and clean bowls, utensils, and surfaces with hot soapy water after handling.
Do not let children eat or play with raw flour dough. Check FDA recall information and discard recalled flour or baking mixes. Home heat treatment may not reliably eliminate hazards. This calculator changes ingredient arithmetic only; it does not validate fermentation, acidity, baking time, internal temperature, cooling, shelf life, packaging, or commercial food-safety controls.
Sourdough hydration questions
Does starter count toward hydration?
Yes. Split starter into its flour and water components and add both to the final formula totals. Ignoring a liquid starter understates both flour and water and can materially misstate true hydration.
What does 100 percent hydration starter mean?
Its water weight equals its flour weight. A 100-gram build made only from flour and water contains 50 grams of each. It does not mean the starter is 100 percent water.
Should milk or eggs count as water?
Not at their full weight unless that is your chosen documented approximation. They contain water plus solids. For precision, count the water component from reliable composition data and place remaining solids with other ingredients.
Why doesn’t scaling include the target-hydration adjustment?
The target result is a diagnostic difference. Scaling applies to the formula actually entered. This separation prevents an unnoticed hydration change from also changing desired dough weight. Update the water field first if you intend to adopt the target.
Why does my 70 percent dough feel wetter than another 75 percent dough?
Flour absorption, grain type, milling, protein, temperature, acidity, mixing, rest, and inclusions influence feel. Percentages compare mass ratios, not rheology. Use controlled test bakes and record flour lots and process.
Is fermented sourdough safe to taste before baking?
No safety guarantee follows from fermentation or acidity. CDC advises not eating raw dough because raw flour and eggs can contain harmful germs. Follow validated cooking or baking directions and safe handling practices.
References
- King Arthur Baking — Hydration in Bread Dough, Explained. Water-to-flour hydration method and starter inclusion.
- King Arthur Baking — Baker’s Percentage. Flour-as-100-percent formula convention and scaling method.
- King Arthur Baking — Sourdough Feeding Ratios. Current feeding-ratio and 100 percent hydration starter context.
- CDC — Raw Flour and Dough. Current U.S. raw-flour, raw-egg, cooking, separation, and cleanup guidance.
- FDA — Handling Flour Safely. Raw-flour hazards, recall, cooking, and household handling guidance.