Fermentation Time Calculator

It starts from a baseline of 4 hours at 24°C with 0.5% instant yeast and 70% hydration, then adjusts that baseline for your actual yeast percentage, dough temperature, leavening type, and hydration. The result is a range, not a single number, because real dough has more variables than any formula captures.

Fermentation rate roughly follows a Q10 of 2.5, meaning yeast activity speeds up about 2.5× for every 10°C increase. A dough at 28°C can finish bulk fermentation in a third of the time the same dough would take at 18°C.

Flour strength, exact room temperature swings, and yeast vitality all shift real fermentation time in ways a calculator cannot see. Use the range as a starting checkpoint, then judge doneness by a 50–75% volume increase and a domed surface rather than the clock.

The calculator applies roughly a 1.6× time factor for sourdough starter compared to instant yeast at the same percentage. Wild yeast and lactic bacteria simply work slower than cultivated commercial yeast, which is part of why sourdough builds more complex flavor over a longer ferment.

Slightly. Wetter doughs give yeast easier access to sugars and oxygen, so higher hydration nudges fermentation a little faster in this calculator. The effect is much smaller than temperature or yeast percentage, so treat it as a minor adjustment, not a primary lever.

For a long room-temperature or retarded overnight bulk, drop instant yeast to 0.1–0.2% baker's percentage. That slows fermentation enough to stretch it over 8–12 hours without over-proofing. For a same-day bake, 0.5–1% is a common starting point.

The formula is calibrated for room-temperature bulk fermentation, not refrigerator temperatures. Below about 4°C, yeast activity slows dramatically and the relationship stops being linear. Treat a fridge retard as "very slow, check visually after 8+ hours" rather than trusting the calculated range at that temperature.