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Sourdough Calculator
Use this free sourdough calculator to plan any loaf before you mix a single gram. Enter your target dough weight, hydration, starter percentage, and salt, and it works out the exact flour, water, starter, and salt you need. It also builds your levain for you, showing how much starter, flour, and water to mix at your chosen feeding ratio, so the starter is ripe and ready right when you need it.
| Ingredient | Amount | Baker's % |
|---|---|---|
| Flour | 520.8 g | 100% |
| Water | 364.6 g | 70% |
| Starter | 104.2 g | 20% |
| Salt | 10.4 g | 2% |
Levain build (1:2:2)
| Levain part | Amount |
|---|---|
| Ripe starter (seed) | 20.8 g |
| Flour | 41.7 g |
| Water | 41.7 g |
| Total levain | 104.2 g |
How it works
Sourdough runs on baker's percentages, just like any bread dough: flour is always 100 percent, and water, starter, and salt are each a percentage of the flour weight. The calculator starts from your target dough weight and works backward. It divides the dough weight by one plus hydration plus starter plus salt (all as decimals) to find the flour. With a 1,000-gram loaf at 70 percent hydration, 20 percent starter, and 2 percent salt, the divisor is 1.92, so the flour is 520.8 grams. Water is flour times hydration, starter is flour times the starter percentage, and salt is flour times the salt percentage — 364.6 grams, 104.2 grams, and 10.4 grams in this example. Add them up and they total exactly 1,000 grams.
Hydration is the most important choice you will make. At 65 to 70 percent, the dough is firm enough to shape easily and holds a tall, round form in the oven — the right range for a first loaf. At 72 to 78 percent, the crumb opens up with larger, irregular holes and the crust gets thinner and crisper, but the dough is softer and needs confident handling and good shaping technique. Above 80 percent, the dough is very wet and really belongs to experienced bakers with strong flour. Whole grain flour absorbs more water, so add 2 to 3 percent hydration for every 20 percent whole grain in the blend.
The starter percentage controls the speed of the ferment and the flavor. Most recipes use 15 to 25 percent starter relative to the flour. More starter — 25 to 30 percent — makes the dough rise faster, which is useful in a cool kitchen, and produces a milder, less tangy loaf. Less starter — 10 to 15 percent — slows everything down, giving the bacteria more time to build the complex, tangy flavor that sourdough is known for, and it is the standard choice for an overnight cold ferment in the fridge.
The levain build is where the feeding ratio comes in. Your recipe needs a certain weight of ripe starter — 104.2 grams in the worked example — and you build exactly that amount by feeding a small amount of your mother starter. A 1:2:2 ratio means one part starter, two parts flour, and two parts water. Dividing the 104.2 grams by five parts gives 20.8 grams of seed starter, fed with 41.7 grams of flour and 41.7 grams of water. A 1:1:1 build peaks faster, in about 4 to 6 hours, because the yeast has less food to work through. A 1:5:5 build takes 10 to 12 hours to peak and is ideal when you want to feed the levain the night before and mix in the morning. A 1:10:10 build is the overnight option for a very warm kitchen or a long schedule.
Salt is added after the flour and water have had a 30 to 60 minute rest, a step bakers call the autolyse. Adding salt late gives the flour time to fully hydrate first, which makes the dough easier to mix and develops better gluten. Two percent salt is the standard: it strengthens the dough, slows the ferment so flavor develops, and seasons the crumb.
Timing is the last piece. At a warm room temperature of 75 to 78 degrees Fahrenheit with 20 percent starter, bulk fermentation usually takes 4 to 6 hours. Rather than watching the clock, watch the dough: it should grow by about 30 to 50 percent, feel light and airy, show bubbles on the surface and along the sides of the bowl, and jiggle like jelly when you shake the bowl gently.
Water = flour × hydration · Starter = flour × starter % · Salt = flour × salt %
Worked example
You want a standard 1,000-gram loaf at 70 percent hydration, 20 percent starter, and 2 percent salt, with a 1:2:2 levain build.
Step 1: Flour — 1,000 ÷ (1 + 0.70 + 0.20 + 0.02) = 1,000 ÷ 1.92 = 520.8 g.
Step 2: Water — 520.8 × 0.70 = 364.6 g.
Step 3: Starter — 520.8 × 0.20 = 104.2 g.
Step 4: Salt — 520.8 × 0.02 = 10.4 g.
Step 5: Levain build — 104.2 g ÷ 5 parts = 20.8 g seed starter + 41.7 g flour + 41.7 g water.
The recipe is 520.8 g flour, 364.6 g water, 104.2 g ripe starter, and 10.4 g salt. Build the levain the evening before with 20.8 g of your mother starter, 41.7 g flour, and 41.7 g water, let it peak overnight, then mix, rest, add the salt, and bulk ferment for 4 to 6 hours before shaping and cold proofing.
FAQ
How much starter do I need for a sourdough loaf?
Most sourdough recipes use 15 to 25 percent starter relative to the flour weight. A 1,000-gram loaf with 20 percent starter needs about 104 grams of ripe starter. More starter makes the dough rise faster and taste milder, while less starter slows the ferment and gives a more tangy, complex flavor.
What hydration is best for sourdough bread?
Beginners should start at 65 to 70 percent hydration, which gives a dough that is easy to shape and holds its form well. Experienced bakers often use 72 to 80 percent for a more open crumb with large holes. Whole grain flour absorbs more water, so a loaf with a lot of whole wheat may need 75 to 85 percent hydration.
What does a 1:2:2 sourdough feeding ratio mean?
A 1:2:2 ratio means one part starter, two parts flour, and two parts water by weight. So 20 grams of starter fed with 40 grams of flour and 40 grams of water gives 100 grams of levain. Higher ratios like 1:5:5 give the yeast more food, so the levain takes longer to peak and tastes milder.
How much salt goes in sourdough bread?
Sourdough typically uses 2 percent salt relative to the flour weight. Salt strengthens the gluten, slows fermentation so flavor can develop, and seasons the loaf. Below 1.5 percent the bread tastes flat, and above 2.5 percent it can noticeably slow the rise.
How long does sourdough take to rise?
With 20 percent starter at a warm room temperature around 75 to 78 degrees Fahrenheit, bulk fermentation usually takes 4 to 6 hours. In a cooler kitchen it can take 6 to 8 hours or more. The best guide is the dough itself: it should grow by about 30 to 50 percent, feel airy, and show bubbles on the surface and sides before you shape it.