Sourdough bread calculator
A loaf on starter alone. How much starter follows from how long and how warm you let it rise.
Fridge hours are counted at 6 °C.
Overall hydration, starter included: 77.2%.
Wheat sourdough bread with no commercial yeast at all. The starter amount is not fixed here: it follows from your time, your temperature and the condition of your starter, the way a baker judges it by eye.
How it works
Starter computed from the plan
Tell it how many hours the dough will ferment and at what temperature, and the calculator sets the starter percentage: a short, warm plan needs more of it, a long, cool one less. The model assumes fermentation speed doubling every ~6 °C, with the fridge at 6 °C.
Starter condition
The same starter can be vigorous (fed regularly, doubling within hours) or weak (straight from the fridge, long unfed). Pick the condition and the dose adjusts — a weak starter gets a larger share.
Hydration and salt
The default 75% water and 2% salt bakes well in a dutch oven or on a stone. Hydration is stated the way bakers state it: water against the flour you weigh out, starter excluded. The line under the recipe gives the overall figure once the starter’s own flour and water are counted in — set your starter’s hydration there if it is not the usual 1:1.
Sources & methodology
Every percentage in this calculator traces to the published sources below — nothing is invented. Where respected sources disagree, the default sits inside the documented range.
- Chad Robertson — “Tartine Bread” (read via The Regular Chef) — The reference proportion for a warm 3–4 h bulk: 200 g of leaven per 1000 g of flour. One of the four bakes the levain model is fitted to.
- The Perfect Loaf — Beginner’s Sourdough Bread — 20.3% levain, 4 h at 24 °C plus 16 h in the fridge, with the schedule written out; his My Best Sourdough (17%, 4 h at 25 °C) is the other bake that sets the middle of the model.
- Breadtopia — Sourdough Pain de Campagne — Pain de campagne at 20% starter, with the longest warm bulk of the four.
- Justyna Dragan — chleb 100% żytni na zakwasie — A 100% rye loaf takes far more starter than the wheat model predicts (37.5% for 6–8 hours). Recorded as the limit of the model, not folded into it.
FAQ
How much starter for a loaf?
It depends on the plan. Five hours at 24 °C followed by a night in the fridge — the default here — lands near 20% of the flour weight, which is where Tartine, The Perfect Loaf and Breadtopia all sit. Warmer, or longer, and it drops. That is why the calculator asks for time and temperature instead of quoting one number.
My starter sat in the fridge for weeks — what do I pick?
Pick “weak”, and ideally refresh it with 1–2 feedings before baking. After two days of regular warm feedings, go back to “normal”.
Can part of the fermentation happen in the fridge?
Yes — the classic move is proofing the shaped loaf overnight in the fridge. Enter the total time and the cold share; at 6 °C fermentation nearly stops, which the model accounts for.
More from Bread
Yeast bread dough calculator
Everyday bread on commercial yeast: flour, water, salt. The dose follows the hours and the temperature you give it.
Hydration 68% · 800 g
Baguette dough calculator
Hamelman's poolish baguette: 66% hydration, a third of the flour fermented overnight.
Hydration 66% · 3 × 335 g
Ciabatta dough calculator
Ciabatta on a stiff biga: 73% hydration, a fifth of the flour fermented overnight. Hence the open crumb.
Hydration 73% · 2 × 530 g
Country sourdough calculator
The Tartine country loaf: 90/10 white and whole wheat, 75% hydration, 20% young levain.
Hydration 75% · 2 × 1000 g
Bread dough calculators15 calculators