How to use the baker's percentage calculator
Choose Plan from percentages when you know the flour you will add, your target total hydration, and the salt percentage. Add the starter weight and its own hydration, or enter zero starter. Calculate, then weigh the displayed water, salt, and starter. Choose Analyze ingredient weights when a formula already gives flour, water, salt, and starter in grams. The result converts those weights into total hydration and salt percentage.
Keep the meaning of the flour field consistent: it is flour added outside the starter. The same is true of the water field. The calculator opens the starter into its flour and water before forming totals, so neither portion is counted twice. Editing any input clears the old result and disables Copy result; calculate again before using the numbers.
Formula, denominator, and starter split
Baker's percentage is not a share of final dough weight. Total flour is the 100% reference, and each other ingredient is compared with that flour. Ingredient percentage = ingredient weight ÷ total flour weight × 100. Hydration is total water ÷ total flour × 100. Because these percentages have a shared flour denominator, their sum can exceed 100% without being an error.
A starter at H% hydration has H parts water for every 100 parts flour. For starter weight S, starter flour is S ÷ (1 + H ÷ 100), and starter water is S minus starter flour. At 100% hydration, 100 g starter becomes 50 g flour and 50 g water. Total flour equals added flour plus starter flour; total water equals added water plus starter water. Salt percentage also uses total flour, not total dough.
Worked examples
Planning example: enter 500 g added flour, 100 g starter at 100% hydration, 70% target hydration, and 2% salt. The starter contributes 50 g flour and 50 g water, so total flour is 550 g. A 70% target needs 385 g total water; subtract the starter's 50 g to get 335 g water to add. Salt is 2% of 550 g, or 11 g. Total dough is 946 g.
Analysis example: enter 500 g flour, 350 g added water, 10 g salt, and 100 g starter at 100% hydration. Totals are 550 g flour and 400 g water. Hydration is 400 ÷ 550 × 100 ≈ 72.73%, and salt is 10 ÷ 550 × 100 ≈ 1.82%. These are flour-based values; calling 400 g water 41.67% of the 960 g dough would answer a different question.
Using the result safely and accurately
Use grams throughout so every ratio compares mass with mass. Decimal commas and decimal points are accepted, up to four decimal places, but thousands separators, fractions, scientific notation, blank values, negatives, and non-finite text are rejected. Displayed values use at most two decimal places while calculations keep their underlying precision. A meaningful positive value below 0.01 is shown as less than 0.01 rather than as zero.
The result is arithmetic, not a bread-quality or fermentation forecast. Flour absorption, whole-grain content, eggs, milk, syrups, soaking water, evaporation, temperature, mixing, and fermentation can change how a dough behaves. Count other sources of flour or water in your own formula before relying on the hydration figure. Copy the result into notes, but retain the original formula and verify the scale before mixing a large batch.
Frequently asked questions
Why is flour always 100%?
It is the common denominator used by baker’s math, not a claim that the dough contains only flour. Every other ingredient is compared with total flour, which makes formulas easy to compare or resize.
Does total flour include the starter?
Yes. The entered flour is the flour added outside the starter. The calculator adds the flour found inside the starter before computing total hydration and salt percentage.
Can starter hydration be different from 100%?
Yes. Enter its actual water-to-flour percentage. A 50% starter contains twice as much flour as water; a 125% starter contains 1.25 times as much water as flour.
Why can the target hydration produce an error?
A wet or large starter may already bring more water than the selected target permits. The calculator will not invent negative added water; raise the target or reduce the starter.
Is this a recipe scaler or fermentation guide?
No. It converts the listed flour, water, salt, and starter relationship only. It does not scale arbitrary ingredient lists, predict fermentation time, recommend food-safety steps, or guarantee bread texture.