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BAKING · BAKER'S PERCENTAGESSourdough Calculator
How much water, starter and salt does your loaf actually need? Enter your flour weight and baker's percentages to get every ingredient weight — in grams or ounces, for one loaf or a whole batch, with a target dough weight mode when you need a loaf of an exact size.
- 100% free, no sign-up
- Grams or ounces
- Flour or dough-weight mode
- Scales to any batch
Every other ingredient is a percentage of the total flour weight — water, starter and salt all scale from it.
The starter's own flour and water are not subtracted — the percentages apply to the flour you weigh out.
A reliable everyday starting point for a 500 g flour loaf — adjust from here to taste.
Set the number of loaves and every weight scales with it — no re-doing the math.
Your dough
Flour mode starts from the flour you weigh out. Dough mode works backwards: enter the dough weight you want and the flour is calculated for you.
Total flour for one loaf, before anything else is added. This is the 100% that every percentage is calculated from.
The finished dough weight you want for one loaf. The flour weight is worked out backwards from your percentages.
Water as a percentage of flour weight.
Starter as a percentage of flour weight, added on top.
Salt as a percentage of flour weight.
Every weight scales with the loaf count.
Please note: weights are a starting recipe, not a guarantee — flour brands absorb water differently, room temperature changes fermentation, and your starter's strength varies. Use the numbers, then adjust by feel on your next bake.
How this sourdough calculator works
Three steps, in the order the formula runs — flour first, percentages second, totals last.
Start from flour
Enter the flour weight for one loaf, or flip to dough mode and enter the finished dough weight you want. Flour is always the 100% everything else is measured against.
Apply the percentages
Water, starter and salt are each a percentage of the flour weight. The starter is added on top — its own flour and water are not subtracted from the totals.
Scale to your batch
Set the number of loaves and every weight scales with it. The results show per-loaf weights and whole-batch totals side by side.
Understanding hydration
Hydration is water as a percentage of flour weight — and it is the single biggest lever on how your dough feels and how your crumb turns out.
Lower hydration (65–70%)
- Firmer, less sticky dough — easier to shape, score and handle
- A tighter, more even crumb with smaller holes
- More forgiving: a good place to start, and easier in warm kitchens
- Best first step if a wetter dough has ever defeated you
Higher hydration (80% and up)
- Wetter, stickier dough — needs confident folding and shaping
- A more open, airy crumb with larger, irregular holes
- Less forgiving: stickier hands, stickier banneton, faster spreading
- Worth working up to once 75% feels comfortable
Worked examples
Three recipes, worked through the same formula. Water, starter and salt are each a percentage of the flour weight, and the starter is added on top.
| Recipe | Flour | Water | Starter | Salt | Total dough |
|---|---|---|---|---|---|
| Classic everyday loaf — 1 loaf, 75% hydration | 500 g | 375 g | 100 g | 10 g | 985 g |
| Two-loaf weekend batch — 2 loaves, 75% hydration | 1,000 g | 750 g | 200 g | 20 g | 1,970 g |
| High-hydration loaf — 1 loaf, 85% hydration | 500 g | 425 g | 100 g | 10 g | 1,035 g |
Example 1: 500 g of flour at 75% hydration gives 375 g of water, at 20% starter gives 100 g of starter, and at 2% salt gives 10 g of salt — 500 + 375 + 100 + 10 = 985 g of dough. Example 2: the same recipe for two loaves doubles everything — 1,000 g of flour, 750 g of water, 200 g of starter, 20 g of salt, 1,970 g of dough. Example 3: raising only the hydration to 85% moves the water to 425 g, so the same loaf weighs 500 + 425 + 100 + 10 = 1,035 g.
Sourdough questions, answered
What is baker's percentage?
Baker's percentage expresses every ingredient as a percentage of the total flour weight, with flour always at 100%. So in a recipe with 500 g of flour at 75% hydration, the water is 75% of 500 g, which is 375 g. On this calculator the starter is added on top of the flour weight: its own flour and water are not subtracted from the totals.
What hydration should a beginner use?
Start around 65% to 70%. Lower-hydration dough is firmer and less sticky, so it is easier to shape, score and handle. Once you are comfortable, move up toward 75% — the default on this calculator — and then higher as your handling improves.
How much starter do I need?
20% of the flour weight is the common default: 100 g of starter for 500 g of flour. More starter generally ferments the dough faster, while less starter slows fermentation down. Adjust the starter percentage on the calculator and every weight updates instantly.
Why 2% salt?
2% of the flour weight — 10 g of salt for 500 g of flour — is the standard balance in bread baking. Salt seasons the loaf and tightens the gluten, giving the dough structure. Much less tastes flat, and much more can slow fermentation.
Can I change hydration for whole-grain flour?
Yes. Whole-grain flours absorb more water than white flour, so raise the hydration a few points — for example from 75% to 78% or 80% — and expect a denser crumb. Change it in small steps and watch how the dough feels; the calculator recomputes every weight as you adjust.