Baker’s math made simple
Sourdough Calculator
Calculate precise flour, water, starter and salt weights—with true dough hydration and per-loaf totals—in seconds. Explore more free baking tools on jobi99.com.
Build your dough formula
Instant resultsAssumption: “total flour” includes the flour carried in your starter. Results update as you type.
Your sourdough recipe
70% hydration — balanced, beginner-friendly sourdough territory.
Total flour 1,000 g · Total water 700 g · Starter ratio 20%
How the math works
- Starter weight1,000 g × 20% = 200 g
- Flour inside starter200 g ÷ (1 + 100%) = 100 g
- Water inside starter200 g − 100 g = 100 g
- Total flour1,000 g total, including starter flour
- Total water1,000 g × 70% = 700 g
- Flour and water to add900 g flour + 600 g water
- Salt1,000 g × 2% = 20 g
- True hydration check700 g ÷ 1,000 g × 100 = 70%
- Total dough weight1,000 g + 700 g + 20 g = 1,720 g
This free sourdough hydration calculator counts the flour and water already in your starter, then gives exact mixing weights. Find more practical recipe helpers and free baking tools on jobi99.com.
How to use this sourdough calculator
- Choose your baseStart with total flour or enter the finished dough weight you need.
- Pick hydrationUse a preset or enter your own water percentage.
- Set starter and saltAdjust starter amount, starter hydration and salt baker’s percentage.
- Mix by weightFollow the flour, water, starter and salt grams in the live result.
Sourdough Hydration Calculator
Hydration is total water divided by total flour. The word total matters because starter carries both into the dough. This calculator separates those amounts, subtracts them from the ingredients added to the bowl, and keeps the chosen hydration accurate.
Use the presets as starting points, not rigid rules. Flour absorption varies, so hold back a little water when testing unfamiliar flour and add it only if the dough can absorb it.
Sourdough Hydration Reference Table
| Hydration | Dough feel | Best starting point for |
|---|---|---|
| 60–65% | Stiff, firm, easier to shape | Bagels and low-hydration dough |
| 70% | Supple and manageable | Sandwich loaves and newer bakers |
| 75% | Soft and extensible | Classic country loaves |
| 80%+ | Wet, delicate and sticky | Open crumb and ciabatta-style bread |
How to Calculate Sourdough Hydration
First split the starter into flour and water. At 100% starter hydration, equal weights of flour and water are present, so 200 g starter contains 100 g flour and 100 g water. Add starter flour to the formula’s flour and starter water to the formula’s water, then divide.
For a target of 1,000 g total flour at 70% hydration, the dough needs 700 g total water. If the formula uses 200 g of 100% hydration starter, add 900 g flour and 600 g water to the bowl. The starter supplies the remaining 100 g flour and 100 g water. This is why true hydration can differ from a recipe that compares only the water and flour poured directly into the mixing bowl.
Sourdough Ratio Calculator
A common starting formula is 100% flour, 70% water, 20% active starter and 2% salt: a 100:70:20:2 flour:water:starter:salt ratio. The calculator turns it into grams and scales without changing the balance. Target dough mode works backward while still counting starter flour and water inside the totals.
Baker's Percentages Explained
In baker’s math, total flour is always 100%. Every other ingredient is measured against that flour weight. With 1,000 g total flour, 75% hydration means 750 g total water, 20% starter means 200 g starter, and 2% salt means 20 g salt. Percentages make recipes easy to compare, double or divide while preserving the same formula.
The live breakdown shows starter flour, starter water, totals, ingredients to add, salt, the true hydration check and dough weight. “Total flour” always includes flour in the starter.
Sourdough Starter Ratio Guide
Starter percentage describes active starter weight as a percentage of total flour on this page. More starter often moves fermentation faster; less starter can support a longer schedule. Dough temperature, room temperature, flour choice and starter strength still matter, so use visible rise and dough feel rather than the percentage as a clock.
Sourdough Starter Ratio Reference Table
| Starter (% of flour) | Typical pace | Useful for |
|---|---|---|
| 5–10% | Slower fermentation | Long schedules and cold-proof planning |
| 15–20% | Standard pace | Everyday room-temperature formulas |
| 25%+ | Faster rise | Shorter schedules or cooler rooms |
Starter feeding ratio is different from starter percentage in dough. A 1:1:1 feeding means one part existing starter, one part flour and one part water by weight. A 1:2:2 feeding uses twice as much fresh flour and water as existing starter. Enter the hydration of the ripe starter you actually add to the dough.
Sourdough Calculator FAQ
What is a sourdough calculator?
It converts baker’s percentages into exact flour, water, starter and salt weights, then shows total dough and weight per loaf.
How do I calculate hydration including starter?
Add the water in the starter to mixing water, add starter flour to mixing flour, then divide total water by total flour and multiply by 100.
What is true hydration versus recipe hydration?
True hydration counts every gram of flour and water, including both inside the starter. A shortcut based only on ingredients added separately can misstate the final percentage.
What hydration is best for beginners?
About 65–70% is a manageable starting range for many bread flours. Begin lower when learning and add held-back water only if the dough can handle it.
What is a standard sourdough bread ratio?
A practical baseline is 100% flour, 70% water, 20% starter and 2% salt, or 100:70:20:2. Adjust hydration for your flour and handling preference.
What is a good sourdough starter ratio?
15–20% starter is a useful standard range. Try 5–10% for a longer schedule or 25% and above when a faster rise suits your conditions.
What is a 1:1:1 sourdough starter feeding ratio?
It means equal weights of existing starter, flour and water. For example, 20 g starter receives 20 g flour and 20 g water.
Can I use cups instead of grams?
Grams are strongly recommended because flour volume changes with scooping and packing. A digital scale gives more repeatable hydration and ratio calculations.
Related sourdough tools and guides
Build your next sourdough formula
Change one variable at a time, copy the gram weights, and keep notes from each bake. For more practical food calculators, visit jobi99.com.
Calculate another recipeCalculator results are formula guidance; fermentation still depends on flour, starter activity and temperature.